diff --git a/ChangeLog.d/private-fields.txt b/ChangeLog.d/private-fields.txt
new file mode 100644
index 0000000..10b9a59
--- /dev/null
+++ b/ChangeLog.d/private-fields.txt
@@ -0,0 +1,5 @@
+API changes
+   * Direct access to fields of structures declared in public headers is no
+     longer supported except for fields that are documented public. Use accessor
+     functions instead. For more information, see the migration guide entry
+     "Most structure fields are now private".
diff --git a/docs/3.0-migration-guide.d/00README b/docs/3.0-migration-guide.d/00README
deleted file mode 100644
index a41733e..0000000
--- a/docs/3.0-migration-guide.d/00README
+++ /dev/null
@@ -1,27 +0,0 @@
-Please add your migration guide entries here. Until 3.0 is released, each PR
-that makes backwards-incompatible changes should add a file here, with the
-extension .md, a descriptive name and the following format:
-
----%<------%<------%<------%<------%<------%<------%<------%<---
-
-The change that was made
-------------------------
-
-Who exactly is affected: does this affect users of the default config, of a
-particular feature? Remember to contextualise.
-
-If I'm affected, what's my migration path? How should I change my code if this
-is an API change; if a feature was removed what are my alternatives?
-
----%<------%<------%<------%<------%<------%<------%<------%<---
-
-PRs that make multiple independent changes should include one entry for each
-changes or logical groups of changes. You can either add multiple files or put
-multiple entries in the same file.
-
-For examples, have a look a docs/3.0-migration-guide.md (which includes the
-top-level header and an intro before the list of entries).
-
-As part of release preparation, the entries in this directory will be appended
-to docs/3.0-migration-guide.md and then re-ordered and reviewed one last time.
-The file is then going to be moved to the version-independent docs repo.
diff --git a/docs/3.0-migration-guide.d/Remove_3DES_ciphersuites.md b/docs/3.0-migration-guide.d/Remove_3DES_ciphersuites.md
deleted file mode 100644
index 0863363..0000000
--- a/docs/3.0-migration-guide.d/Remove_3DES_ciphersuites.md
+++ /dev/null
@@ -1,10 +0,0 @@
-Remove 3DES ciphersuites
---
-
-This change does not affect users using default settings for 3DES in `mbedtls_config.h`
-because the 3DES ciphersuites were disabled by that.
-
-3DES has weaknesses/limitations and there are better alternatives, and more and
-more standard bodies are recommending against its use in TLS.
-
-The migration path here is to chose from the recomended in literature alternatives.
diff --git a/docs/3.0-migration-guide.d/ccm-alt.md b/docs/3.0-migration-guide.d/ccm-alt.md
deleted file mode 100644
index 1abac7a..0000000
--- a/docs/3.0-migration-guide.d/ccm-alt.md
+++ /dev/null
@@ -1,9 +0,0 @@
-CCM interface changes: impact for alternative implementations
--------------------------------------------------------------
-
-The CCM interface has changed with the addition of support for
-multi-part operations. Five new API functions have been defined:
-mbedtls_ccm_starts(), mbedtls_ccm_set_lengths(),
-mbedtls_ccm_update_ad(), mbedtls_ccm_update() and mbedtls_ccm_finish().
-Alternative implementations of CCM (`MBEDTLS_CCM_ALT`) have now to
-implement those additional five API functions.
diff --git a/docs/3.0-migration-guide.d/cipher-delayed-output.md b/docs/3.0-migration-guide.d/cipher-delayed-output.md
deleted file mode 100644
index 18d3271..0000000
--- a/docs/3.0-migration-guide.d/cipher-delayed-output.md
+++ /dev/null
@@ -1,15 +0,0 @@
-Calling `mbedtls_cipher_finish()` is mandatory for all multi-part operations
-----------------------------------------------------------------------------
-
-This only affects people who use the cipher module to perform AEAD operations
-using the multi-part API.
-
-Previously, the documentation didn't state explicitly if it was OK to call
-`mbedtls_cipher_check_tag()` or `mbedtls_cipher_write_tag()` directly after
-the last call to `mbedtls_cipher_update()` - that is, without calling
-`mbedtls_cipher_finish()` in-between. If you code was missing that call,
-please add it and be prepared to get as much as 15 bytes of output.
-
-Currently the output is always 0 bytes, but it may be more when alternative
-implementations of the underlying primitives are in use, or with future
-versions of the library.
diff --git a/docs/3.0-migration-guide.d/combine_SSL_CID-TLS1_3_PADDING_GRANULARITY_options.md b/docs/3.0-migration-guide.d/combine_SSL_CID-TLS1_3_PADDING_GRANULARITY_options.md
deleted file mode 100644
index c4005cf..0000000
--- a/docs/3.0-migration-guide.d/combine_SSL_CID-TLS1_3_PADDING_GRANULARITY_options.md
+++ /dev/null
@@ -1,14 +0,0 @@
-Combine the `MBEDTLS_SSL_CID_PADDING_GRANULARITY` and `MBEDTLS_SSL_TLS1_3_PADDING_GRANULARITY` options
---
-
-This change affects users who modified the default `mbedtls_config.h` padding granularity
-settings, i.e. enabled at least one of the options.
-
-The `mbedtls_config.h` options `MBEDTLS_SSL_CID_PADDING_GRANULARITY` and
-`MBEDTLS_SSL_TLS1_3_PADDING_GRANULARITY` were combined into one option because
-they used exactly the same padding mechanism and hence their respective padding
-granularities can be used in exactly the same way. This change simplifies the
-code maintenance.
-
-The new single option `MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY` can be used
-for both DTLS-CID and TLS 1.3.
diff --git a/docs/3.0-migration-guide.d/csr-add-critical-extension.md b/docs/3.0-migration-guide.d/csr-add-critical-extension.md
deleted file mode 100644
index ebcb343..0000000
--- a/docs/3.0-migration-guide.d/csr-add-critical-extension.md
+++ /dev/null
@@ -1,9 +0,0 @@
-Change the API to allow adding critical extensions to CSRs
-------------------------------------------------------------------
-
-This affects applications that call the `mbedtls_x509write_csr_set_extension`
-function.
-
-The API is changed to include the parameter `critical` which allow to mark an
-extension included in a CSR as critical. To get the previous behaviour pass
-`0`.
diff --git a/docs/3.0-migration-guide.d/default-curves.md b/docs/3.0-migration-guide.d/default-curves.md
deleted file mode 100644
index 928130d..0000000
--- a/docs/3.0-migration-guide.d/default-curves.md
+++ /dev/null
@@ -1,25 +0,0 @@
-Strengthen default algorithm selection for X.509 and TLS
---------------------------------------------------------
-
-The default X.509 verification profile (`mbedtls_x509_crt_profile_default`) and the default curve and hash selection in TLS have changed. They are now aligned, except that the X.509 profile only lists curves that support signature verification.
-
-Hashes and curves weaker than 255 bits (security strength less than 128 bits) are no longer accepted by default. The following hashes have been removed: SHA-1 (formerly only accepted for key exchanges but not for certificate signatures), SHA-224 (weaker hashes were already not accepted). The following curves have been removed: secp192r1, secp224r1, secp192k1, secp224k1.
-
-The compile-time options `MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_CERTIFICATES` and `MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE` are no longer available.
-
-The curve secp256k1 has also been removed from the default X.509 and TLS profiles. [RFC 8422](https://datatracker.ietf.org/doc/html/rfc8422#section-5.1.1) deprecates it in TLS, and it is very rarely used, although it is not known to be weak at the time of writing.
-
-If you still need to accept certificates signed with algorithms that have been removed from the default profile, call `mbedtls_x509_crt_verify_with_profile` instead of `mbedtls_x509_crt_verify` and pass a profile that allows the curves and hashes you want. For example, to allow SHA-224:
-```
-mbedtls_x509_crt_profile my_profile = mbedtls_x509_crt_profile_default;
-my_profile.allowed_mds |= MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 );
-```
-
-If you still need to allow hashes and curves in TLS that have been removed from the default configuration, call `mbedtls_ssl_conf_sig_hashes()` and `mbedtls_ssl_conf_curves()` with the desired lists.
-
-TLS now favors faster curves over larger curves
------------------------------------------------
-
-The default preference order for curves in TLS now favors resource usage (performance and memory consumption) over size. The exact order is unspecified and may change, but generally you can expect 256-bit curves to be preferred over larger curves.
-
-If you prefer a different order, call `mbedtls_ssl_conf_curves()` when configuring a TLS connection.
diff --git a/docs/3.0-migration-guide.d/gcm-alt.md b/docs/3.0-migration-guide.d/gcm-alt.md
deleted file mode 100644
index 388e2be..0000000
--- a/docs/3.0-migration-guide.d/gcm-alt.md
+++ /dev/null
@@ -1,10 +0,0 @@
-GCM interface changes: impact for alternative implementations
--------------------------------------------------------------
-
-The GCM multipart interface has changed as described in [“GCM multipart interface: application changes”](#gcm-multipart-interface:-application-changes). The consequences for an alternative implementation of GCM (`MBEDTLS_GCM_ALT`) are as follows:
-
-* `mbedtls_gcm_starts()` now only sets the mode and the nonce (IV). The new function `mbedtls_gcm_update_ad()` receives the associated data. It may be called multiple times.
-* `mbedtls_gcm_update()` now allows arbitrary-length inputs, takes an extra parameter to indicate the actual output length. Alternative implementations may choose between two modes:
-    * Always return the partial output immediately, even if it does not consist of a whole number of blocks.
-    * Buffer the data for the last partial block, to be returned in the next call to `mbedtls_gcm_update()` or `mbedtls_gcm_finish()`.
-* `mbedtls_gcm_finish()` now takes an extra output buffer for the last partial block if needed.
diff --git a/docs/3.0-migration-guide.d/gcm-multipart.md b/docs/3.0-migration-guide.d/gcm-multipart.md
deleted file mode 100644
index ebc6397..0000000
--- a/docs/3.0-migration-guide.d/gcm-multipart.md
+++ /dev/null
@@ -1,12 +0,0 @@
-GCM multipart interface: application changes
---------------------------------------------
-
-The GCM module now supports arbitrary chunked input in the multipart interface.
-This changes the interface for applications using the GCM module directly for multipart operations.
-Applications using one-shot GCM or using GCM via the `mbedtls_cipher_xxx` or `psa_aead_xxx` interfaces do not require any changes.
-
-* `mbedtls_gcm_starts()` now only sets the mode and the nonce (IV). Call the new function `mbedtls_gcm_update_ad()` to pass the associated data.
-* `mbedtls_gcm_update()` now takes an extra parameter to indicate the actual output length. In Mbed TLS 2.x, applications had to pass inputs consisting of whole 16-byte blocks except for the last block (this limitation has been lifted). In this case:
-    * As long as the input remains block-aligned, the output length is exactly the input length, as before.
-    * If the length of the last input is not a multiple of 16, alternative implementations may return the last partial block in the call to `mbedtls_gcm_finish()` instead of returning it in the last call to `mbedtls_gcm_update()`.
-* `mbedtls_gcm_finish()` now takes an extra output buffer for the last partial block. This is needed for alternative implementations that can only process a whole block at a time.
diff --git a/docs/3.0-migration-guide.d/key-export.md b/docs/3.0-migration-guide.d/key-export.md
deleted file mode 100644
index f8b3505..0000000
--- a/docs/3.0-migration-guide.d/key-export.md
+++ /dev/null
@@ -1,36 +0,0 @@
-SSL key export interface change
--------------------------------
-
-This affects users of the SSL key export APIs:
-```
-    mbedtls_ssl_conf_export_keys_cb()
-    mbedtls_ssl_conf_export_keys_ext_cb()
-```
-
-Those APIs have been removed and replaced by the new API
-`mbedtls_ssl_set_export_keys_cb()`. This API differs from
-the previous key export API in the following ways:
-
-- It is no longer bound to an SSL configuration, but to an
-  SSL context. This allows users to more easily identify the
-  connection an exported key belongs to.
-- It no longer exports raw keys and IV.
-- A secret type parameter has been added to identify which key
-  is being exported. For TLS 1.2, only the master secret is
-  exported, but upcoming TLS 1.3 support will add other kinds of keys.
-- The callback now specifies a void return type, rather than
-  returning an error code. It is the responsibility of the application
-  to handle failures in the key export callback, for example by
-  shutting down the TLS connection.
-
-For users which do not rely on raw keys and IV, adjusting to the new
-callback type should be straightforward - see the example programs
-programs/ssl/ssl_client2 and programs/ssl/ssl_server2 for callbacks
-for NSSKeylog, EAP-TLS and DTLS-SRTP.
-
-Users which require access to the raw keys used to secure application
-traffic may derive those by hand based on the master secret and the
-handshake transcript hashes which can be obtained from the raw data
-on the wire. Such users are also encouraged to reach out to the
-Mbed TLS team on the mailing list, to let the team know about their
-use case.
diff --git a/docs/3.0-migration-guide.d/mandatory-rng-param.md b/docs/3.0-migration-guide.d/mandatory-rng-param.md
deleted file mode 100644
index f6aba08..0000000
--- a/docs/3.0-migration-guide.d/mandatory-rng-param.md
+++ /dev/null
@@ -1,40 +0,0 @@
-The RNG parameter is now mandatory for all functions that accept one
---------------------------------------------------------------------
-
-This change affects all users who called a function accepting a `f_rng`
-parameter with `NULL` as the value of this argument; this is no longer
-supported.
-
-The changed functions are: the X.509 CRT and CSR writing functions; the PK and
-RSA sign and decrypt functions; `mbedtls_rsa_private()`; the functions in DHM
-and ECDH that compute the shared secret; the scalar multiplication functions in
-ECP.
-
-You now need to pass a properly seeded, cryptographically secure RNG to all
-functions that accept a `f_rng` parameter. It is of course still possible to
-pass `NULL` as the context pointer `p_rng` if your RNG function doesn't need a
-context.
-
-Alternative implementations of a module (enabled with the `MBEDTLS_module_ALT`
-configuration options) may have their own internal and are free to ignore the
-`f_rng` argument but must allow users to pass one anyway.
-
-Some functions gained an RNG parameter
---------------------------------------
-
-This affects users of the following functions: `mbedtls_ecp_check_pub_priv()`,
-`mbedtls_pk_check_pair()`, `mbedtls_pk_parse_key()`, and
-`mbedtls_pk_parse_keyfile()`.
-
-You now need to pass a properly seeded, cryptographically secure RNG when
-calling these functions. It is used for blinding, a counter-measure against
-side-channel attacks.
-
-The configuration option `MBEDTLS_ECP_NO_INTERNAL_RNG` was removed
-------------------------------------------------------------------
-
-This doesn't affect users of the default configuration; it only affects people
-who were explicitly setting this option.
-
-This was a trade-off between code size and counter-measures; it is no longer
-relevant as the counter-measure is now always on at no cost in code size.
diff --git a/docs/3.0-migration-guide.d/max-record-payload-api.md b/docs/3.0-migration-guide.d/max-record-payload-api.md
deleted file mode 100644
index 0b34915..0000000
--- a/docs/3.0-migration-guide.d/max-record-payload-api.md
+++ /dev/null
@@ -1,11 +0,0 @@
-Remove MaximumFragmentLength (MFL) query API
------------------------------------------------------------------
-
-This affects users which use the MFL query APIs
-`mbedtls_ssl_get_{input,output}_max_frag_len()` to
-infer upper bounds on the plaintext size of incoming and
-outgoing record.
-
-Users should switch to `mbedtls_ssl_get_max_{in,out}_record_payload()`
-instead, which also provides such upper bounds but takes more factors
-than just the MFL configuration into account.
diff --git a/docs/3.0-migration-guide.d/modify_MBEDTLS_ECP_FIXED_POINT_OPTIM_behaviour.md b/docs/3.0-migration-guide.d/modify_MBEDTLS_ECP_FIXED_POINT_OPTIM_behaviour.md
deleted file mode 100644
index 91bec72..0000000
--- a/docs/3.0-migration-guide.d/modify_MBEDTLS_ECP_FIXED_POINT_OPTIM_behaviour.md
+++ /dev/null
@@ -1,11 +0,0 @@
-Change MBEDTLS_ECP_FIXED_POINT_OPTIM behaviour
-------------------------------------------------------
-
-The option `MBEDTLS_ECP_FIXED_POINT_OPTIM` now increase code size and it does
-not increase peak RAM usage anymore.
-
-If you are limited by code size, you can define `MBEDTLS_ECP_FIXED_POINT_OPTIM`
-to `0` in your config file. The impact depends on the number and size of
-enabled curves. For example, for P-256 the difference is 1KB; see the documentation
-of this option for details.
-
diff --git a/docs/3.0-migration-guide.d/modify_SHA384_option_behaviour.md b/docs/3.0-migration-guide.d/modify_SHA384_option_behaviour.md
deleted file mode 100644
index 68eacfc..0000000
--- a/docs/3.0-migration-guide.d/modify_SHA384_option_behaviour.md
+++ /dev/null
@@ -1,12 +0,0 @@
-Replaced MBEDTLS_SHA512_NO_SHA384 with MBEDTLS_SHA384_C
-------------------------------------------------------
-
-This does not affect users who use the default `mbedtls_config.h`.
-MBEDTLS_SHA512_NO_SHA384 was disabled by default, now MBEDTLS_SHA384_C is
-enabled by default.
-
-If you were using a config file with both MBEDTLS_SHA512_C and
-MBEDTLS_SHA512_NO_SHA384, then just remove the MBEDTLS_SHA512_NO_SHA384.
-If you were using a config file with MBEDTLS_SHA512_C and without
-MBEDTLS_SHA512_NO_SHA384 and you need the SHA-384 algorithm, then add
-`#define MBEDTLS_SHA384_C` to your config file.
diff --git a/docs/3.0-migration-guide.d/move_part_of_timing_module_out_of_the_library.md b/docs/3.0-migration-guide.d/move_part_of_timing_module_out_of_the_library.md
deleted file mode 100644
index fa61e27..0000000
--- a/docs/3.0-migration-guide.d/move_part_of_timing_module_out_of_the_library.md
+++ /dev/null
@@ -1,9 +0,0 @@
-Move part of timing module out of the library
---
-
-The change affects users who use any of the following functions:
-`mbedtls_timing_self_test()`, `mbedtls_hardclock_poll()`,
-`mbedtls_timing_hardclock()` and `mbedtls_set_alarm()`.
-
-If you were relying on these functions, you'll now need to change to using your
-platform's corresponding functions directly.
diff --git a/docs/3.0-migration-guide.d/out_size.md b/docs/3.0-migration-guide.d/out_size.md
deleted file mode 100644
index 49d3246..0000000
--- a/docs/3.0-migration-guide.d/out_size.md
+++ /dev/null
@@ -1,9 +0,0 @@
-Extra parameter for the output buffer size
-------------------------------------------
-
-The following functions now take an extra parameter indicating the size of the output buffer:
-
-* `mbedtls_ecdsa_write_signature()`, `mbedtls_ecdsa_write_signature_restartable()`
-* `mbedtls_pk_sign()`, `mbedtls_pk_sign_restartable()`
-
-The requirements for the output buffer have not changed, but passing a buffer that is too small now reliably causes the functions to return an error, rather than overflowing the buffer.
diff --git a/docs/3.0-migration-guide.d/relaxed-psk-semantics.md b/docs/3.0-migration-guide.d/relaxed-psk-semantics.md
deleted file mode 100644
index 6b0e794..0000000
--- a/docs/3.0-migration-guide.d/relaxed-psk-semantics.md
+++ /dev/null
@@ -1,18 +0,0 @@
-Relaxed semantics for PSK configuration
------------------------------------------------------------------
-
-This affects users which call the PSK configuration APIs
-`mbedtlsl_ssl_conf_psk()` and `mbedtls_ssl_conf_psk_opaque()`
-multiple times on the same SSL configuration.
-
-In Mbed TLS 2.x, users would observe later calls overwriting
-the effect of earlier calls, with the prevailing PSK being
-the one that has been configured last. In Mbed TLS 3.0,
-calling `mbedtls_ssl_conf_[opaque_]psk()` multiple times
-will return an error, leaving the first PSK intact.
-
-To achieve equivalent functionality when migrating to Mbed TLS 3.0,
-users calling `mbedtls_ssl_conf_[opaque_]psk()` multiple times should
-remove all but the last call, so that only one call to _either_
-`mbedtls_ssl_conf_psk()` _or_ `mbedtls_ssl_conf_psk_opaque()`
-remains.
diff --git a/docs/3.0-migration-guide.d/remove-enable-weak-ciphersuites.md b/docs/3.0-migration-guide.d/remove-enable-weak-ciphersuites.md
deleted file mode 100644
index 917d1ac..0000000
--- a/docs/3.0-migration-guide.d/remove-enable-weak-ciphersuites.md
+++ /dev/null
@@ -1,12 +0,0 @@
-Remove the configuration to enable weak ciphersuites in SSL / TLS
------------------------------------------------------------------
-
-This does not affect users who use the default `mbedtls_config.h`, as this option was
-already off by default.
-
-If you were using a weak cipher, please switch to any of the modern,
-recommended ciphersuites (based on AES-GCM, AES-CCM or ChachaPoly for example)
-and if your peer doesn't support any, encourage them to upgrade their software.
-
-If you were using a ciphersuite without encryption, you just have to
-enable MBEDTLS_CIPHER_NULL_CIPHER now.
diff --git a/docs/3.0-migration-guide.d/remove-max-content-len.md b/docs/3.0-migration-guide.d/remove-max-content-len.md
deleted file mode 100644
index 40c7d53..0000000
--- a/docs/3.0-migration-guide.d/remove-max-content-len.md
+++ /dev/null
@@ -1,10 +0,0 @@
-Remove the `MBEDTLS_SSL_MAX_CONTENT_LEN` configuration option
--------------------------------------------------------------
-
-This affects users who use the `MBEDTLS_SSL_MAX_CONTENT_LEN` option to
-set the maximum length of incoming and outgoing plaintext fragments,
-which can save memory by reducing the size of the TLS I/O buffers.
-
-This option is replaced by the more fine-grained options
-`MBEDTLS_SSL_IN_CONTENT_LEN` and `MBEDTLS_SSL_OUT_CONTENT_LEN` that set
-the maximum incoming and outgoing plaintext fragment lengths, respectively.
diff --git a/docs/3.0-migration-guide.d/remove-null-entropy.md b/docs/3.0-migration-guide.d/remove-null-entropy.md
deleted file mode 100644
index c38c930..0000000
--- a/docs/3.0-migration-guide.d/remove-null-entropy.md
+++ /dev/null
@@ -1,11 +0,0 @@
-Remove the option to build the library without any entropy sources
-------------------------------------------------------------------
-
-This does not affect users who use the default `mbedtls_config.h`, as this option was
-already off by default.
-
-If you were using the `MBEDTLS_TEST_NULL_ENTROPY` option and your platform
-doesn't have any entropy source, you should use `MBEDTLS_ENTROPY_NV_SEED`
-and make sure your device is provisioned with a strong random seed.
-Alternatively, for testing purposes only, you can create and register a fake
-entropy function.
diff --git a/docs/3.0-migration-guide.d/remove-rsa-mode-parameter.md b/docs/3.0-migration-guide.d/remove-rsa-mode-parameter.md
deleted file mode 100644
index d21d5ed..0000000
--- a/docs/3.0-migration-guide.d/remove-rsa-mode-parameter.md
+++ /dev/null
@@ -1,21 +0,0 @@
-Remove the mode parameter from RSA functions
---------------------------------------------
-
-This affects all users who use the RSA encryption, decryption, sign and
-verify APIs.
-
-The RSA module no longer supports private-key operations with the public key or
-vice versa. As a consequence, RSA operation functions no longer have a mode
-parameter. If you were calling RSA operations with the normal mode (public key
-for verification or encryption, private key for signature or decryption), remove
-the `MBEDTLS_MODE_PUBLIC` or `MBEDTLS_MODE_PRIVATE` argument. If you were calling
-RSA operations with the wrong mode, which rarely makes sense from a security
-perspective, this is no longer supported.
-
-Remove the RNG parameter from RSA verify functions
---------------------------------------------------
-
-RSA verification functions also no longer take random generator arguments (this
-was only needed when using a private key). This affects all applications using
-the RSA verify functions.
-
diff --git a/docs/3.0-migration-guide.d/remove-ssl-get-session_pointer.md b/docs/3.0-migration-guide.d/remove-ssl-get-session_pointer.md
deleted file mode 100644
index a4a4895..0000000
--- a/docs/3.0-migration-guide.d/remove-ssl-get-session_pointer.md
+++ /dev/null
@@ -1,23 +0,0 @@
-Remove the SSL API mbedtls_ssl_get_session_pointer()
------------------------------------------------------------------
-
-This affects two classes of users:
-
-1. Users who manually inspect parts of the current session through
-   direct structure field access.
-
-2. Users of session resumption who query the current session
-   via `mbedtls_ssl_get_session_pointer()` prior to saving or exporting
-   it via `mbedtls_ssl_session_copy()` or `mbedtls_ssl_session_save()`,
-   respectively.
-
-Migration paths:
-
-1. Mbed TLS 3.0 does not offer a migration path for the usecase 1: Like many
-   other Mbed TLS structures, the structure of `mbedtls_ssl_session` is no
-   longer part of the public API in Mbed TLS 3.0, and direct structure field
-   access is no longer supported. Please see the corresponding migration guide.
-
-2. Users should replace calls to `mbedtls_ssl_get_session_pointer()` by
-   calls to `mbedtls_ssl_get_session()` as demonstrated in the example
-   program `programs/ssl/ssl_client2.c`.
diff --git a/docs/3.0-migration-guide.d/remove_MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION.md b/docs/3.0-migration-guide.d/remove_MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION.md
deleted file mode 100644
index 738fa81..0000000
--- a/docs/3.0-migration-guide.d/remove_MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION.md
+++ /dev/null
@@ -1,17 +0,0 @@
-Remove the config option MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION
---------------------------------------------------------------------------
-
-This change does not affect users of the default configuration; it only affect
-users who enable this option.
-
-The X.509 standard says that implementations must reject critical extensions that
-they don't recognize, and this is what Mbed TLS does by default. This option
-allowed to continue parsing those certificates but didn't provide a convenient
-way to handle those extensions.
-
-The migration path from that option is to use the
-`mbedtls_x509_crt_parse_der_with_ext_cb()` function which is functionally
-equivalent to `mbedtls_x509_crt_parse_der()`, and/or
-`mbedtls_x509_crt_parse_der_nocopy()` but it calls the callback with every
-unsupported certificate extension and additionally the "certificate policies"
-extension if it contains any unsupported certificate policies.
diff --git a/docs/3.0-migration-guide.d/remove_MBEDTLS_X509_CHECK_x_KEY_USAGE_options.md b/docs/3.0-migration-guide.d/remove_MBEDTLS_X509_CHECK_x_KEY_USAGE_options.md
deleted file mode 100644
index ebb4be9..0000000
--- a/docs/3.0-migration-guide.d/remove_MBEDTLS_X509_CHECK_x_KEY_USAGE_options.md
+++ /dev/null
@@ -1,18 +0,0 @@
-Remove `MBEDTLS_X509_CHECK_*_KEY_USAGE` options from `mbedtls_config.h`
--------------------------------------------------------------------
-
-This change affects users who have chosen the configuration options to disable the
-library's verification of the `keyUsage` and `extendedKeyUsage` fields of x509
-certificates.
-
-The `MBEDTLS_X509_CHECK_KEY_USAGE` and `MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE`
-configuration options are removed and the X509 code now behaves as if they were
-always enabled. It is consequently not possible anymore to disable at compile
-time the verification of the `keyUsage` and `extendedKeyUsage` fields of X509
-certificates.
-
-The verification of the `keyUsage` and `extendedKeyUsage` fields is important,
-disabling it can cause security issues and it is thus not recommended. If the
-verification is for some reason undesirable, it can still be disabled by means
-of the verification callback function passed to `mbedtls_x509_crt_verify()` (see
-the documentation of this function for more information).
diff --git a/docs/3.0-migration-guide.d/remove_MD2_MD4_RC4_Blowfish_XTEA.md b/docs/3.0-migration-guide.d/remove_MD2_MD4_RC4_Blowfish_XTEA.md
deleted file mode 100644
index d199f2f..0000000
--- a/docs/3.0-migration-guide.d/remove_MD2_MD4_RC4_Blowfish_XTEA.md
+++ /dev/null
@@ -1,8 +0,0 @@
-Remove MD2, MD4, RC4, Blowfish and XTEA algorithms
---
-
-This change affects users of the MD2, MD4, RC4, Blowfish and XTEA algorithms.
-
-They are already niche or obsolete and most of them are weak or broken. For
-those reasons possible users should consider switching to modern and safe
-alternatives to be found in literature.
diff --git a/docs/3.0-migration-guide.d/remove_SSL_DTLS_BADMAC_LIMIT_option.md b/docs/3.0-migration-guide.d/remove_SSL_DTLS_BADMAC_LIMIT_option.md
deleted file mode 100644
index 3c0cbe9..0000000
--- a/docs/3.0-migration-guide.d/remove_SSL_DTLS_BADMAC_LIMIT_option.md
+++ /dev/null
@@ -1,11 +0,0 @@
-Remove MBEDTLS_SSL_DTLS_BADMAC_LIMIT option
--------------------------------------------
-
-This change does not affect users who used the default `mbedtls_config.h`, as the option
-MBEDTLS_SSL_DTLS_BADMAC_LIMIT was already on by default.
-
-This option was a trade-off between functionality and code size: it allowed
-users who didn't need that feature to avoid paying the cost in code size, by
-disabling it.
-
-This option is no longer present, but its functionality is now always enabled.
diff --git a/docs/3.0-migration-guide.d/remove_deprecated_functions_and_constants.md b/docs/3.0-migration-guide.d/remove_deprecated_functions_and_constants.md
deleted file mode 100644
index 31c2ce8..0000000
--- a/docs/3.0-migration-guide.d/remove_deprecated_functions_and_constants.md
+++ /dev/null
@@ -1,74 +0,0 @@
-Deprecated functions were removed from AES
-------------------------------------------
-
-The functions `mbedtls_aes_encrypt()` and `mbedtls_aes_decrypt()` were
-removed.
-
-If you're simply using the AES module, you should be calling the higher-level
-functions `mbedtls_aes_crypt_xxx()`.
-
-If you're providing an alternative implementation using
-`MBEDTLS_AES_ENCRYPT_ALT` or `MBEDTLS_AES_DECRYPT_ALT`, you should be
-replacing the removed functions with `mbedtls_internal_aes_encrypt()` and
-`mbedtls_internal_aes_decrypt()` respectively.
-
-Deprecated functions were removed from bignum
----------------------------------------------
-
-The function `mbedtls_mpi_is_prime()` was removed. Please use
-`mbedtls_mpi_is_prime_ext()` instead which additionally allows specifying the
-number of Miller-Rabin rounds.
-
-Deprecated functions were removed from cipher
----------------------------------------------
-
-The functions `mbedtls_cipher_auth_encrypt()` and
-`mbedtls_cipher_auth_decrypt()` were removed. They were superseded by
-`mbedtls_cipher_auth_encrypt_ext()` and `mbedtls_cipher_auth_decrypt_ext()`
-respectively which additionally support key wrapping algorithms such as
-NIST_KW.
-
-Deprecated functions were removed from DRBGs
---------------------------------------------
-
-The functions `mbedtls_ctr_drbg_update()` and `mbedtls_hmac_drbg_update()`
-were removed. They were superseded by `mbedtls_ctr_drbg_update_ret()` and
-`mbedtls_hmac_drbg_update_ret()` respectively.
-
-Deprecated functions were removed from ECDSA
---------------------------------------------
-
-The functions `mbedtls_ecdsa_write_signature_det()` and
-`mbedtls_ecdsa_sign_det()` were removed. They were superseded by
-`mbedtls_ecdsa_write_signature()` and `mbedtls_ecdsa_sign_det_ext()`
-respectively.
-
-Deprecated functions were removed from SSL
-------------------------------------------
-
-The function `mbedtls_ssl_conf_dh_param()` was removed. Please use
-`mbedtls_ssl_conf_dh_param_bin()` or `mbedtls_ssl_conf_dh_param_ctx()` instead.
-
-The function `mbedtls_ssl_get_max_frag_len()` was removed. Please use
-`mbedtls_ssl_get_max_out_record_payload()` and
-`mbedtls_ssl_get_max_in_record_payload()`
-instead.
-
-Deprecated hex-encoded primes were removed from DHM
----------------------------------------------------
-
-The macros `MBEDTLS_DHM_RFC5114_MODP_2048_P`, `MBEDTLS_DHM_RFC5114_MODP_2048_G`,
-`MBEDTLS_DHM_RFC3526_MODP_2048_P`, `MBEDTLS_DHM_RFC3526_MODP_2048_G`,
-`MBEDTLS_DHM_RFC3526_MODP_3072_P`, `MBEDTLS_DHM_RFC3526_MODP_3072_G`,
-`MBEDTLS_DHM_RFC3526_MODP_4096_P `and `MBEDTLS_DHM_RFC3526_MODP_4096_G` were
-removed. The primes from RFC 5114 are deprecated because their derivation is not
-documented and therefore their usage constitutes a security risk; they are fully
-removed from the library. Please use parameters from RFC3526 (still in the
-library, only in binary form) or RFC 7919 (also available in the library) or
-other trusted sources instead.
-
-Deprecated net.h file was removed
----------------------------------
-
-The file `include/mbedtls/net.h` was removed because its only function was to
-include `mbedtls/net_sockets.h` which now should be included directly.
diff --git a/docs/3.0-migration-guide.d/remove_mbedtls_check_params_option.md b/docs/3.0-migration-guide.d/remove_mbedtls_check_params_option.md
deleted file mode 100644
index 6f43aa3..0000000
--- a/docs/3.0-migration-guide.d/remove_mbedtls_check_params_option.md
+++ /dev/null
@@ -1,33 +0,0 @@
-Remove MBEDTLS_CHECK_PARAMS option
-----------------------------------
-
-This change does not affect users who use the default configuration; it only
-affects users who enabled that option.
-
-The option `MBEDTLS_CHECK_PARAMS` (disabled by default) enabled certain kinds
-of “parameter validation”. It covered two kinds of validations:
-
-- In some functions that require a valid pointer, “parameter validation” checks
-that the pointer is non-null. With the feature disabled, a null pointer is not
-treated differently from any other invalid pointer, and typically leads to a
-runtime crash. 90% of the uses of the feature are of this kind.
-- In some functions that take an enum-like argument, “parameter validation”
-checks that the value is a valid one. With the feature disabled, an invalid
-value causes a silent default to one of the valid values.
-
-The default reaction to a failed check was to call a function
-`mbedtls_param_failed()` which the application had to provide. If this function
-returned, its caller returned an error `MBEDTLS_ERR_xxx_BAD_INPUT_DATA`.
-
-This feature was only used in some classic (non-PSA) cryptography modules. It was
-not used in X.509, TLS or in PSA crypto, and it was not implemented in all
-classic crypto modules.
-
-This feature has been removed. The library no longer checks for NULL pointers;
-checks for enum-like arguments will be kept or re-introduced on a case-by-case
-basis, but their presence will no longer be dependent on a compile-time option.
-
-Validation of enum-like values is somewhat useful, but not extremely important,
-because the parameters concerned are usually constants in applications.
-
-For more information see issue #4313.
diff --git a/docs/3.0-migration-guide.d/remove_ssl_record_checking.md b/docs/3.0-migration-guide.d/remove_ssl_record_checking.md
deleted file mode 100644
index 7bee4ae..0000000
--- a/docs/3.0-migration-guide.d/remove_ssl_record_checking.md
+++ /dev/null
@@ -1,13 +0,0 @@
-Remove MBEDTLS_SSL_RECORD_CHECKING option and enable its action by default
---------------------------------------------------------------------------
-
-This change does not affect users who use the default mbedtls_config.h, as the
-option MBEDTLS_SSL_RECORD_CHECKING was already on by default.
-
-This option was added only to control compilation of one function,
-mbedtls_ssl_check_record(), which is only useful in some specific cases, so it
-was made optional to allow users who don't need it to save some code space.
-However, the same effect can be achieve by using link-time garbage collection.
-
-Users who changed the default setting of the option need to change the config/
-build system to remove that change.
diff --git a/docs/3.0-migration-guide.d/remove_supp_for_extensions_in_pre-v3_X_509_certs.md b/docs/3.0-migration-guide.d/remove_supp_for_extensions_in_pre-v3_X_509_certs.md
deleted file mode 100644
index 4c87f03..0000000
--- a/docs/3.0-migration-guide.d/remove_supp_for_extensions_in_pre-v3_X_509_certs.md
+++ /dev/null
@@ -1,14 +0,0 @@
-Remove the `MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3` option
---
-
-This change does not affect users who were using the default configuration, as
-this option was already disabled by default. Also, it does not affect users who
-are working with current V3 X.509 certificates.
-
-Extensions were added in V3 of the X.509 specification, so pre-V3 certificates
-containing extensions were never compliant. Mbed TLS now rejects them with a
-parsing error in all configurations, as it did previously in the default
-configuration.
-
-If you are working with the pre-V3 certificates you need to switch to the
-current ones.
diff --git a/docs/3.0-migration-guide.d/remove_support_for_tls_1.0_1.1_and_dtls_1.0.md b/docs/3.0-migration-guide.d/remove_support_for_tls_1.0_1.1_and_dtls_1.0.md
deleted file mode 100644
index 73d621f..0000000
--- a/docs/3.0-migration-guide.d/remove_support_for_tls_1.0_1.1_and_dtls_1.0.md
+++ /dev/null
@@ -1,27 +0,0 @@
-Remove suport for TLS 1.0, 1.1 and DTLS 1.0
--------------------------------------------
-
-This change affects users of the TLS 1.0, 1.1 and DTLS 1.0 protocols.
-
-These versions have been deprecated by RFC 8996.
-Keeping them in the library creates opportunities for misconfiguration
-and possibly downgrade attacks. More generally, more code means a larger attack
-surface, even if the code is supposedly not used.
-
-The migration path is to adopt the latest versions of the protocol.
-
-As a consequence of removing TLS 1.0, support for CBC record splitting was
-also removed, as it was a work-around for a weakness in this particular
-version. There is no migration path since the feature is no longer relevant.
-
-As a consequence of currently supporting only one version of (D)TLS (and in the
-future 1.3 which will have a different version negociation mechanism), support
-for fallback SCSV (RFC 7507) was also removed. There is no migration path as
-it's no longer useful with TLS 1.2 and later.
-
-As a consequence of currently supporting only one version of (D)TLS (and in the
-future 1.3 which will have a different concept of ciphersuites), support for
-configuring ciphersuites separately for each version via
-`mbedtls_ssl_conf_ciphersuites_for_version()` was removed. Use
-`mbedtls_ssl_conf_ciphersuites()` to configure ciphersuites to use with (D)TLS
-1.2; in the future a different API will be added for (D)TLS 1.3.
diff --git a/docs/3.0-migration-guide.d/rename_the__ret_functions.md b/docs/3.0-migration-guide.d/rename_the__ret_functions.md
deleted file mode 100644
index 875164b..0000000
--- a/docs/3.0-migration-guide.d/rename_the__ret_functions.md
+++ /dev/null
@@ -1,43 +0,0 @@
-Rename mbedtls_*_ret() cryptography functions whose deprecated variants
-have been removed
------------------
-
-This change affects users who were using the `mbedtls_*_ret()` cryptography
-functions.
-
-Those functions were created based on now-deprecated functions according to a
-requirement that a function needs to return a value. This change brings back the
-original names of those functions. The renamed functions are:
-
-| name before this change      | after the change         |
-|------------------------------|--------------------------|
-| mbedtls_ctr_drbg_update_ret  | mbedtls_ctr_drbg_update  |
-| mbedtls_hmac_drbg_update_ret | mbedtls_hmac_drbg_update |
-| mbedtls_md5_starts_ret       | mbedtls_md5_starts       |
-| mbedtls_md5_update_ret       | mbedtls_md5_update       |
-| mbedtls_md5_finish_ret       | mbedtls_md5_finish       |
-| mbedtls_md5_ret              | mbedtls_md5              |
-| mbedtls_ripemd160_starts_ret | mbedtls_ripemd160_starts |
-| mbedtls_ripemd160_update_ret | mbedtls_ripemd160_update |
-| mbedtls_ripemd160_finish_ret | mbedtls_ripemd160_finish |
-| mbedtls_ripemd160_ret        | mbedtls_ripemd160        |
-| mbedtls_sha1_starts_ret      | mbedtls_sha1_starts      |
-| mbedtls_sha1_update_ret      | mbedtls_sha1_update      |
-| mbedtls_sha1_finish_ret      | mbedtls_sha1_finish      |
-| mbedtls_sha1_ret             | mbedtls_sha1             |
-| mbedtls_sha256_starts_ret    | mbedtls_sha256_starts    |
-| mbedtls_sha256_update_ret    | mbedtls_sha256_update    |
-| mbedtls_sha256_finish_ret    | mbedtls_sha256_finish    |
-| mbedtls_sha256_ret           | mbedtls_sha256           |
-| mbedtls_sha512_starts_ret    | mbedtls_sha512_starts    |
-| mbedtls_sha512_update_ret    | mbedtls_sha512_update    |
-| mbedtls_sha512_finish_ret    | mbedtls_sha512_finish    |
-| mbedtls_sha512_ret           | mbedtls_sha512           |
-
-To migrate to the this change the user can keep the `*_ret` names in their code
-and include the `compat_2.x.h` header file which holds macros with proper
-renaming or to rename those function in their code according to the list from
-mentioned header file.
-
-
-
diff --git a/docs/3.0-migration-guide.d/require-matching-hashlen-rsa.md b/docs/3.0-migration-guide.d/require-matching-hashlen-rsa.md
deleted file mode 100644
index d59a8d3..0000000
--- a/docs/3.0-migration-guide.d/require-matching-hashlen-rsa.md
+++ /dev/null
@@ -1,24 +0,0 @@
-Signature functions now require the hash length to match the expected value
----------------------------------------------------------------------------
-
-This affects users of the PK API as well as users of the low-level API in the RSA module. Users of the PSA API or of the ECDSA module are unaffected.
-
-All the functions in the RSA module that accept a `hashlen` parameter used to
-ignore it unless the `md_alg` parameter was `MBEDTLS_MD_NONE`, indicating raw
-data was signed. The `hashlen` parameter is now always the size that is read
-from the `hash` input buffer. This length must be equal to the output size of
-the hash algorithm used when signing a hash. (The requirements when signing
-raw data are unchanged.) This affects the following functions:
-
-* `mbedtls_rsa_pkcs1_sign`, `mbedtls_rsa_pkcs1_verify`
-* `mbedtls_rsa_rsassa_pkcs1_v15_sign`, `mbedtls_rsa_rsassa_pkcs1_v15_verify`
-* `mbedtls_rsa_rsassa_pss_sign`, `mbedtls_rsa_rsassa_pss_verify`
-* `mbedtls_rsa_rsassa_pss_sign_ext`, `mbedtls_rsa_rsassa_pss_verify_ext`
-
-The signature functions in the PK module no longer accept 0 as the `hash_len` parameter. The `hash_len` parameter is now always the size that is read from the `hash` input buffer. This affects the following functions:
-
-* `mbedtls_pk_sign`, `mbedtls_pk_verify`
-* `mbedtls_pk_sign_restartable`, `mbedtls_pk_verify_restartable`
-* `mbedtls_pk_verify_ext`
-
-The migration path is to pass the correct value to those functions.
diff --git a/docs/3.0-migration-guide.d/rsa-padding.md b/docs/3.0-migration-guide.d/rsa-padding.md
deleted file mode 100644
index f10ece6..0000000
--- a/docs/3.0-migration-guide.d/rsa-padding.md
+++ /dev/null
@@ -1,29 +0,0 @@
-Remove the padding parameters from mbedtls_rsa_init()
------------------------------------------------------
-
-This affects all users who use the RSA encryption, decryption, sign and
-verify APIs.
-
-The function mbedtls_rsa_init() no longer supports selecting the PKCS#1 v2.1
-encoding and its hash. It just selects the PKCS#1 v1.5 encoding by default. If
-you were using the PKCS#1 v2.1 encoding you now need, subsequently to the call
-to mbedtls_rsa_init(), to call mbedtls_rsa_set_padding() to set it.
-
-To choose the padding type when initializing a context, instead of
-```C
-    mbedtls_rsa_init(ctx, padding, hash_id);
-```
-, use
-```C
-    mbedtls_rsa_init(ctx);
-    mbedtls_rsa_set_padding(ctx, padding, hash_id);
-```
-
-To use PKCS#1 v1.5 padding, instead of
-```C
-    mbedtls_rsa_init(ctx, MBEDTLS_RSA_PKCS_V15, <ignored>);
-```
-, just use
-```C
-    mbedtls_rsa_init(ctx);
-```
diff --git a/docs/3.0-migration-guide.d/separate_SHA224_from_SHA256.md b/docs/3.0-migration-guide.d/separate_SHA224_from_SHA256.md
deleted file mode 100644
index f5a8d98..0000000
--- a/docs/3.0-migration-guide.d/separate_SHA224_from_SHA256.md
+++ /dev/null
@@ -1,11 +0,0 @@
-Separated MBEDTLS_SHA224_C and MBEDTLS_SHA256_C
------------------------------------------------------------------
-
-This does not affect users who use the default `mbedtls_config.h`. MBEDTLS_SHA256_C
-was enabled by default. Now both MBEDTLS_SHA256_C and MBEDTLS_SHA224_C are
-enabled.
-
-If you were using custom config file with MBEDTLS_SHA256_C enabled, then
-you will need to add `#define MBEDTLS_SHA224_C` option your config.
-Current version of the library does not support enabling MBEDTLS_SHA256_C
-without MBEDTLS_SHA224_C.
diff --git a/docs/3.0-migration-guide.d/session-cache-api.md b/docs/3.0-migration-guide.d/session-cache-api.md
deleted file mode 100644
index b28ce19..0000000
--- a/docs/3.0-migration-guide.d/session-cache-api.md
+++ /dev/null
@@ -1,28 +0,0 @@
-Session Cache API Change
------------------------------------------------------------------
-
-This affects users who use `mbedtls_ssl_conf_session_cache()`
-to configure a custom session cache implementation different
-from the one Mbed TLS implements in `library/ssl_cache.c`.
-
-Those users will need to modify the API of their session cache
-implementation to that of a key-value store with keys being
-session IDs and values being instances of `mbedtls_ssl_session`:
-
-```
-typedef int mbedtls_ssl_cache_get_t( void *data,
-                                     unsigned char const *session_id,
-                                     size_t session_id_len,
-                                     mbedtls_ssl_session *session );
-typedef int mbedtls_ssl_cache_set_t( void *data,
-                                     unsigned char const *session_id,
-                                     size_t session_id_len,
-                                     const mbedtls_ssl_session *session );
-```
-
-Since the structure of `mbedtls_ssl_session` is no longer public from 3.0
-onwards, portable session cache implementations must not access fields of
-`mbedtls_ssl_session`. See the corresponding migration guide. Users that
-find themselves unable to migrate their session cache functionality without
-accessing fields of `mbedtls_ssl_session` should describe their usecase
-on the Mbed TLS mailing list.
diff --git a/docs/3.0-migration-guide.d/sha512-output-type.md b/docs/3.0-migration-guide.d/sha512-output-type.md
deleted file mode 100644
index c62a881..0000000
--- a/docs/3.0-migration-guide.d/sha512-output-type.md
+++ /dev/null
@@ -1,8 +0,0 @@
-SHA-512 and SHA-256 output type change
---------------------------
-
-The output parameter of `mbedtls_sha256_finish_ret()`, `mbedtls_sha256_ret()`, `mbedtls_sha512_finish_ret()`, `mbedtls_sha512_ret()` now has a pointer type rather than array type. This makes no difference in terms of C semantics, but removes spurious warnings in some compilers when outputting a SHA-384 hash into a 48-byte buffer or a SHA-224 hash into a 28-byte buffer.
-
-This makes no difference to a vast majority of applications. If your code takes a pointer to one of these functions, you may need to change the type of the pointer.
-
-Alternative implementations of the SHA256 and SHA512 modules must adjust their functions' prototype accordingly.
diff --git a/docs/3.0-migration-guide.d/split_config.md b/docs/3.0-migration-guide.d/split_config.md
deleted file mode 100644
index 6f433c5..0000000
--- a/docs/3.0-migration-guide.d/split_config.md
+++ /dev/null
@@ -1,20 +0,0 @@
-Introduce a level of indirection and versioning in the config files
--------------------------------------------------------------------
-
-`config.h` was split into `build_info.h` and `mbedtls_config.h`.
-
-* In code, use `#include <mbedtls/build_info.h>`. Don't include `mbedtls/config.h` and don't refer to `MBEDTLS_CONFIG_FILE`.
-* In build tools, edit `mbedtls_config.h`, or edit `MBEDTLS_CONFIG_FILE` as before.
-* If you had a tool that parsed the library version from `include/mbedtls/version.h`, this has moved to `include/mbedtls/build_info.h`. From C code, both headers now define the `MBEDTLS_VERSION_xxx` macros.
-
-Also, if you have a custom configuration file:
-
-* Don't include `check_config.h` or `config_psa.h` anymore.
-* Don't define `MBEDTLS_CONFIG_H` anymore.
-
-A config file version symbol, `MBEDTLS_CONFIG_VERSION` was introduced.
-Defining it to a particular value will ensure that Mbed TLS interprets
-the config file in a way that's compatible with the config file format
-used by the Mbed TLS release whose `MBEDTLS_VERSION_NUMBER` has the same
-value.
-The only value supported by Mbed TLS 3.0.0 is `0x03000000`.
diff --git a/docs/3.0-migration-guide.d/ssl-error-code-cleanup.md b/docs/3.0-migration-guide.d/ssl-error-code-cleanup.md
deleted file mode 100644
index ce795e5..0000000
--- a/docs/3.0-migration-guide.d/ssl-error-code-cleanup.md
+++ /dev/null
@@ -1,39 +0,0 @@
-Changes in the SSL error code space
------------------------------------------------------------------
-
-# Removals
-
-This affects users manually checking for the following error codes:
-- `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED`
-- `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH`
-- `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE`
-- `MBEDTLS_ERR_SSL_BAD_HS_XXX`
-
-Migration paths:
-
-- `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED` and `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH`
-  should never be returned from Mbed TLS, and there is no need to check for it.
-
-  Users should simply remove manual checks for those codes, and let the Mbed TLS
-  team know if -- contrary to the team's understanding -- there is in fact a situation
-  where one of them was ever returned.
-
-- `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE` has been removed, and
-  `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` is returned instead if the user's own certificate
-  is too large to fit into the output buffers.
-
-  Users should check for
-  `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` instead, and potentially compare the size of their
-  own certificate against the configured size of the output buffer to understand if
-  the error is due to an overly large certificate.
-
-- All `MBEDTLS_ERR_SSL_BAD_HS_XXX` error code have been removed.
-
-  Users should check for the newly introduced generic error codes
-  * `MBEDTLS_ERR_SSL_DECODE_ERROR`
-  * `MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER`,
-  * `MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE`
-  * `MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION`
-  * `MBEDTLS_ERR_SSL_BAD_CERTIFICATE`
-  * `MBEDTLS_ERR_SSL_UNRECOGNIZED_NAME`
-  instead.
diff --git a/docs/3.0-migration-guide.d/ssl-ticket-api.md b/docs/3.0-migration-guide.d/ssl-ticket-api.md
deleted file mode 100644
index 23c53d6..0000000
--- a/docs/3.0-migration-guide.d/ssl-ticket-api.md
+++ /dev/null
@@ -1,30 +0,0 @@
-Modified semantics of mbedtls_ssl_{get,set}_session()
------------------------------------------------------------------
-
-This affects users who call `mbedtls_ssl_get_session()` or
-`mbedtls_ssl_set_session()` multiple times on the same SSL context
-representing an established TLS 1.2 connection.
-Those users will now observe the second call to fail with
-`MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE`.
-
-Migration path:
-- Exporting the same TLS 1.2 connection multiple times via
-  `mbedtls_ssl_get_session()` leads to multiple copies of
-  the same session. This use of `mbedtls_ssl_get_session()`
-  is discouraged, and the following should be considered:
-  * If the various session copies are later loaded into
-    fresh SSL contexts via `mbedtls_ssl_set_session()`,
-    export via `mbedtls_ssl_get_session()` only once and
-    load the same session into different contexts via
-    `mbedtls_ssl_set_session()`. Since `mbedtls_ssl_set_session()`
-    makes a copy of the session that's being loaded, this
-    is functionally equivalent.
-  * If the various session copies are later serialized
-    via `mbedtls_ssl_session_save()`, export and serialize
-    the session only once via `mbedtls_ssl_get_session()` and
-    `mbedtls_ssl_session_save()` and make copies of the raw
-    data instead.
-- Calling `mbedtls_ssl_set_session()` multiple times in Mbed TLS 2.x
-  is not useful since subsequent calls overwrite the effect of previous
-  calls. Applications achieve equivalent functional behaviour by
-  issuing only the very last call to `mbedtls_ssl_set_session()`.
diff --git a/docs/3.0-migration-guide.d/turn_SSL_SRV_RESPECT_CLIENT_PREFERENCE_config_opt_to_runtime_opt.md b/docs/3.0-migration-guide.d/turn_SSL_SRV_RESPECT_CLIENT_PREFERENCE_config_opt_to_runtime_opt.md
deleted file mode 100644
index 6f5a13a..0000000
--- a/docs/3.0-migration-guide.d/turn_SSL_SRV_RESPECT_CLIENT_PREFERENCE_config_opt_to_runtime_opt.md
+++ /dev/null
@@ -1,14 +0,0 @@
-Turn MBEDTLS_SSL_SRV_RESPECT_CLIENT_PREFERENCE configuration option into a runtime option
---
-
-This change affects users who were enabling MBEDTLS_SSL_SRV_RESPECT_CLIENT_PREFERENCE
-option in the `mbedtls_config.h`
-
-This option has been removed and a new function with similar functionality has
-been introduced into the SSL API.
-
-This new function `mbedtls_ssl_conf_preference_order()` can be used to
-change the preferred order of ciphersuites on the server to those used on the client,
-e.g.: `mbedtls_ssl_conf_preference_order(ssl_config, MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_CLIENT)`
-has the same effect as enabling the removed option. The default state is to use
-the server order of suites.
diff --git a/docs/3.0-migration-guide.md b/docs/3.0-migration-guide.md
index 5fe6ebd..a814c92 100644
--- a/docs/3.0-migration-guide.md
+++ b/docs/3.0-migration-guide.md
@@ -1,5 +1,4 @@
-Migrating from Mbed TLS 2.x to Mbed TLS 3.0
-===========================================
+# Migrating from Mbed TLS 2.x to Mbed TLS 3.0
 
 This guide details the steps required to migrate from Mbed TLS version 2.x to
 Mbed TLS version 3.0 or greater. Unlike normal releases, Mbed TLS 3.0 breaks
@@ -9,8 +8,436 @@
 Here's the list of breaking changes; each entry should help you answer these
 two questions: (1) am I affected? (2) if yes, what's my migration path?
 
-Some function parameters were made const
-----------------------------------------
+The changes are detailed below, and include:
+
+- Removal of many insecure or obsolete features
+- Tidying up of configuration options (including removing some less useful options).
+- Changing function signatures, e.g. adding return codes, adding extra parameters, or making some arguments const.
+- Removal of functions previously marked as deprecated.
+
+
+## General changes
+
+### Introduce a level of indirection and versioning in the config files
+
+`config.h` was split into `build_info.h` and `mbedtls_config.h`.
+
+* In code, use `#include <mbedtls/build_info.h>`. Don't include `mbedtls/config.h` and don't refer to `MBEDTLS_CONFIG_FILE`.
+* In build tools, edit `mbedtls_config.h`, or edit `MBEDTLS_CONFIG_FILE` as before.
+* If you had a tool that parsed the library version from `include/mbedtls/version.h`, this has moved to `include/mbedtls/build_info.h`. From C code, both headers now define the `MBEDTLS_VERSION_xxx` macros.
+
+Also, if you have a custom configuration file:
+
+* Don't include `check_config.h` or `config_psa.h` anymore.
+* Don't define `MBEDTLS_CONFIG_H` anymore.
+
+A config file version symbol, `MBEDTLS_CONFIG_VERSION` was introduced.
+Defining it to a particular value will ensure that Mbed TLS interprets
+the config file in a way that's compatible with the config file format
+used by the Mbed TLS release whose `MBEDTLS_VERSION_NUMBER` has the same
+value.
+The only value supported by Mbed TLS 3.0.0 is `0x03000000`.
+
+### Most structure fields are now private
+
+Direct access to fields of structures (`struct` types) declared in public headers is no longer supported. In Mbed TLS 3, the layout of structures is not considered part of the stable API, and minor versions (3.1, 3.2, etc.) may add, remove, rename, reorder or change the type of structure fields.
+
+There is a small number of exceptions where some fields are guaranteed to remain stable throughout the lifetime of Mbed TLS 3.x. These fields are explicitly documented as public. Please note that even if all the fields of a structure are public, future versions may add new fields. Also, as before, some public fields should be considered read-only, since modifying them may make the structure inconsistent; check the documentation in each case.
+
+Attempting to access a private field directly will result in a compilation error.
+
+If you were accessing structure fields directly, and these fields are not documented as public, you need to change your code. If an accessor (getter/setter) function exists, use that. Direct accessor functions are usually called `mbedtls_<MODULE>_{get,set}_<FIELD>` or `mbedtls_<MODULE>_<STRUCTURE>_{get,set}_<FIELD>`. Accessor functions that change the format may use different verbs, for example `read`/`write` for functions that import/export data from/to a text or byte string.
+
+If no accessor function exists, please open an [enhancement request against Mbed TLS](https://github.com/ARMmbed/mbedtls/issues/new?template=feature_request.md) and describe your use case. The Mbed TLS development team is aware that some useful accessor functions are missing in the 3.0 release, and we expect to add them to the first minor release(s) (3.1, etc.).
+
+As a last resort, you can access the field `foo` of a structure `bar` by writing `bar.MBEDTLS_PRIVATE(foo)`. Note that you do so at your own risk, since such code is likely to break in a future minor version of Mbed TLS.
+
+### Move part of timing module out of the library
+
+The change affects users who use any of the following functions:
+`mbedtls_timing_self_test()`, `mbedtls_hardclock_poll()`,
+`mbedtls_timing_hardclock()` and `mbedtls_set_alarm()`.
+
+If you were relying on these functions, you'll now need to change to using your
+platform's corresponding functions directly.
+
+### Deprecated net.h file was removed
+
+The file `include/mbedtls/net.h` was removed because its only function was to
+include `mbedtls/net_sockets.h` which now should be included directly.
+
+### Remove `MBEDTLS_CHECK_PARAMS` option
+
+This change does not affect users who use the default configuration; it only
+affects users who enabled that option.
+
+The option `MBEDTLS_CHECK_PARAMS` (disabled by default) enabled certain kinds
+of “parameter validation”. It covered two kinds of validations:
+
+- In some functions that require a valid pointer, “parameter validation” checks
+that the pointer is non-null. With the feature disabled, a null pointer is not
+treated differently from any other invalid pointer, and typically leads to a
+runtime crash. 90% of the uses of the feature are of this kind.
+- In some functions that take an enum-like argument, “parameter validation”
+checks that the value is a valid one. With the feature disabled, an invalid
+value causes a silent default to one of the valid values.
+
+The default reaction to a failed check was to call a function
+`mbedtls_param_failed()` which the application had to provide. If this function
+returned, its caller returned an error `MBEDTLS_ERR_xxx_BAD_INPUT_DATA`.
+
+This feature was only used in some classic (non-PSA) cryptography modules. It was
+not used in X.509, TLS or in PSA crypto, and it was not implemented in all
+classic crypto modules.
+
+This feature has been removed. The library no longer checks for NULL pointers;
+checks for enum-like arguments will be kept or re-introduced on a case-by-case
+basis, but their presence will no longer be dependent on a compile-time option.
+
+Validation of enum-like values is somewhat useful, but not extremely important,
+because the parameters concerned are usually constants in applications.
+
+For more information see issue #4313.
+
+### Remove the `MBEDTLS_TEST_NULL_ENTROPY` configuration option
+
+This does not affect users who use the default `mbedtls_config.h`, as this option was
+already off by default.
+
+If you were using the `MBEDTLS_TEST_NULL_ENTROPY` option and your platform
+doesn't have any entropy source, you should use `MBEDTLS_ENTROPY_NV_SEED`
+and make sure your device is provisioned with a strong random seed.
+Alternatively, for testing purposes only, you can create and register a fake
+entropy function.
+
+### Remove the HAVEGE module
+
+This doesn't affect people using the default configuration as it was already
+disabled by default.
+
+This only affects users who called the HAVEGE modules directly (not
+recommended), or users who used it through the entropy module but had it as the
+only source of entropy. If you're in that case, please declare OS or hardware
+RNG interfaces with `mbedtls_entropy_add_source()` and/or use an entropy seed
+file created securely during device provisioning. See
+<https://tls.mbed.org/kb/how-to/add-entropy-sources-to-entropy-pool> for more
+information.
+
+### Remove helpers for the transition from Mbed TLS 1.3 to Mbed TLS 2.0
+
+This only affects people who've been using Mbed TLS since before version 2.0
+and still relied on `compat-1.3.h` in their code.
+
+Please use the new names directly in your code; `scripts/rename.pl` (from any
+of the 2.x releases — no longer included in 3.0) might help you do that.
+
+
+## Low-level crypto
+
+Please also refer to the section [High-level crypto](#high-level-crypto) for
+changes that could sit in either category.
+
+### Deprecated functions were removed from bignum
+
+The function `mbedtls_mpi_is_prime()` was removed. Please use
+`mbedtls_mpi_is_prime_ext()` instead which additionally allows specifying the
+number of Miller-Rabin rounds.
+
+### Deprecated functions were removed from DRBGs
+
+The functions `mbedtls_ctr_drbg_update_ret()` and `mbedtls_hmac_drbg_update_ret()`
+were renamed to replace the corresponding functions without `_ret` appended. Please call
+the name without `_ret` appended and check the return value.
+
+### Deprecated hex-encoded primes were removed from DHM
+
+The macros `MBEDTLS_DHM_RFC5114_MODP_2048_P`, `MBEDTLS_DHM_RFC5114_MODP_2048_G`,
+`MBEDTLS_DHM_RFC3526_MODP_2048_P`, `MBEDTLS_DHM_RFC3526_MODP_2048_G`,
+`MBEDTLS_DHM_RFC3526_MODP_3072_P`, `MBEDTLS_DHM_RFC3526_MODP_3072_G`,
+`MBEDTLS_DHM_RFC3526_MODP_4096_P `and `MBEDTLS_DHM_RFC3526_MODP_4096_G` were
+removed. The primes from RFC 5114 are deprecated because their derivation is not
+documented and therefore their usage constitutes a security risk; they are fully
+removed from the library. Please use parameters from RFC3526 (still in the
+library, only in binary form) or RFC 7919 (also available in the library) or
+other trusted sources instead.
+
+### Deprecated functions were removed from hashing modules
+
+Modules: MD5, SHA1, SHA256, SHA512, MD.
+
+- The functions `mbedtls_xxx_starts_ret()`, `mbedtls_xxx_update_ret()`,
+  `mbedtls_xxx_finish_ret()` and `mbedtls_xxx_ret()` were renamed to replace
+  the corresponding functions without `_ret` appended. Please call the name without `_ret` appended and check the return value.
+- The function `mbedtls_md_init_ctx()` was removed; please use
+  `mbedtls_md_setup()` instead.
+- The functions `mbedtls_xxx_process()` were removed. You normally don't need
+  to call that from application code. However if you do (or if you want to
+  provide your own version of that function), please use
+  `mbedtls_internal_xxx_process()` instead, and check the return value.
+
+### Change `MBEDTLS_ECP_FIXED_POINT_OPTIM` behavior
+
+The option `MBEDTLS_ECP_FIXED_POINT_OPTIM` now increases code size and it does
+not increase peak RAM usage anymore.
+
+If you are limited by code size, you can define `MBEDTLS_ECP_FIXED_POINT_OPTIM`
+to `0` in your config file. The impact depends on the number and size of
+enabled curves. For example, for P-256 the difference is 1KB; see the documentation
+of this option for details.
+
+### Separated `MBEDTLS_SHA224_C` and `MBEDTLS_SHA256_C`
+
+This does not affect users who use the default `mbedtls_config.h`. `MBEDTLS_SHA256_C`
+was enabled by default. Now both `MBEDTLS_SHA256_C` and `MBEDTLS_SHA224_C` are
+enabled.
+
+If you were using custom config file with `MBEDTLS_SHA256_C` enabled, then
+you will need to add `#define MBEDTLS_SHA224_C` option to your config.
+Current version of the library does not support enabling `MBEDTLS_SHA256_C`
+without `MBEDTLS_SHA224_C`.
+
+### Replaced `MBEDTLS_SHA512_NO_SHA384` with `MBEDTLS_SHA384_C`
+
+This does not affect users who use the default `mbedtls_config.h`.
+`MBEDTLS_SHA512_NO_SHA384` was disabled by default, now `MBEDTLS_SHA384_C` is
+enabled by default.
+
+If you were using a config file with both `MBEDTLS_SHA512_C` and
+MBEDTLS_SHA512_NO_SHA384, then just remove the `MBEDTLS_SHA512_NO_SHA384`.
+If you were using a config file with `MBEDTLS_SHA512_C` and without
+`MBEDTLS_SHA512_NO_SHA384` and you need the SHA-384 algorithm, then add
+`#define MBEDTLS_SHA384_C` to your config file.
+
+### GCM multipart interface: application changes
+
+The GCM module now supports arbitrary chunked input in the multipart interface.
+This changes the interface for applications using the GCM module directly for multipart operations.
+Applications using one-shot GCM or using GCM via the `mbedtls_cipher_xxx` or `psa_aead_xxx` interfaces do not require any changes.
+
+* `mbedtls_gcm_starts()` now only sets the mode and the nonce (IV). Call the new function `mbedtls_gcm_update_ad()` to pass the associated data.
+* `mbedtls_gcm_update()` now takes an extra parameter to indicate the actual output length. In Mbed TLS 2.x, applications had to pass inputs consisting of whole 16-byte blocks except for the last block (this limitation has been lifted). In this case:
+    * As long as the input remains block-aligned, the output length is exactly the input length, as before.
+    * If the length of the last input is not a multiple of 16, alternative implementations may return the last partial block in the call to `mbedtls_gcm_finish()` instead of returning it in the last call to `mbedtls_gcm_update()`.
+* `mbedtls_gcm_finish()` now takes an extra output buffer for the last partial block. This is needed for alternative implementations that can only process a whole block at a time.
+
+### GCM interface changes: impact for alternative implementations
+
+The GCM multipart interface has changed as described in [“GCM multipart interface: application changes”](#gcm-multipart-interface-application-changes). The consequences for an alternative implementation of GCM (`MBEDTLS_GCM_ALT`) are as follows:
+
+* `mbedtls_gcm_starts()` now only sets the mode and the nonce (IV). The new function `mbedtls_gcm_update_ad()` receives the associated data. It may be called multiple times.
+* `mbedtls_gcm_update()` now allows arbitrary-length inputs, takes an extra parameter to indicate the actual output length. Alternative implementations may choose between two modes:
+    * Always return the partial output immediately, even if it does not consist of a whole number of blocks.
+    * Buffer the data for the last partial block, to be returned in the next call to `mbedtls_gcm_update()` or `mbedtls_gcm_finish()`.
+* `mbedtls_gcm_finish()` now takes an extra output buffer for the last partial block if needed.
+
+### The configuration option `MBEDTLS_ECP_NO_INTERNAL_RNG` was removed
+
+This doesn't affect users of the default configuration; it only affects people
+who were explicitly setting this option.
+
+This was a trade-off between code size and countermeasures; it is no longer
+relevant as the countermeasure is now always on at no cost in code size.
+
+### SHA-512 and SHA-256 output type change
+
+The output parameter of `mbedtls_sha256_finish_ret()`, `mbedtls_sha256_ret()`, `mbedtls_sha512_finish_ret()`, `mbedtls_sha512_ret()` now has a pointer type rather than array type. This makes no difference in terms of C semantics, but removes spurious warnings in some compilers when outputting a SHA-384 hash into a 48-byte buffer or a SHA-224 hash into a 28-byte buffer.
+
+This makes no difference to a vast majority of applications. If your code takes a pointer to one of these functions, you may need to change the type of the pointer.
+
+Alternative implementations of the SHA256 and SHA512 modules must adjust their functions' prototype accordingly.
+
+### Deprecated error codes for hardware failures were removed
+
+- The macros `MBEDTLS_ERR_xxx_FEATURE_UNSUPPORTED` from various crypto modules
+  were removed; `MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED` is now used
+  instead.
+- The macros `MBEDTLS_ERR_xxx_HW_ACCEL_FAILED` from various crypto modules
+  were removed; `MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED` is now used instead.
+
+### Remove the mode parameter from RSA functions
+
+This affects all users who use the RSA encryption, decryption, sign and
+verify APIs.
+
+The RSA module no longer supports private-key operations with the public key or
+vice versa. As a consequence, RSA operation functions no longer have a mode
+parameter. If you were calling RSA operations with the normal mode (public key
+for verification or encryption, private key for signature or decryption), remove
+the `MBEDTLS_MODE_PUBLIC` or `MBEDTLS_MODE_PRIVATE` argument. If you were calling
+RSA operations with the wrong mode, which rarely makes sense from a security
+perspective, this is no longer supported.
+
+### Deprecated functions were removed from AES
+
+The functions `mbedtls_aes_encrypt()` and `mbedtls_aes_decrypt()` were
+removed.
+
+If you're simply using the AES module, you should be calling the higher-level
+functions `mbedtls_aes_crypt_xxx()`.
+
+If you're providing an alternative implementation using
+`MBEDTLS_AES_ENCRYPT_ALT` or `MBEDTLS_AES_DECRYPT_ALT`, you should be
+replacing the removed functions with `mbedtls_internal_aes_encrypt()` and
+`mbedtls_internal_aes_decrypt()` respectively.
+
+### Deprecated functions were removed from ECDSA
+
+The functions `mbedtls_ecdsa_write_signature_det()` and
+`mbedtls_ecdsa_sign_det()` were removed. They were superseded by
+`mbedtls_ecdsa_write_signature()` and `mbedtls_ecdsa_sign_det_ext()`
+respectively.
+
+### Rename `mbedtls_*_ret()` cryptography functions whose deprecated variants have been removed
+
+This change affects users who were using the `mbedtls_*_ret()` cryptography
+functions.
+
+Those functions were created based on now-deprecated functions according to a
+requirement that a function needs to return a value. This change brings back the
+original names of those functions. The renamed functions are:
+
+| name before this change        | after the change           |
+|--------------------------------|----------------------------|
+| `mbedtls_ctr_drbg_update_ret`  | `mbedtls_ctr_drbg_update`  |
+| `mbedtls_hmac_drbg_update_ret` | `mbedtls_hmac_drbg_update` |
+| `mbedtls_md5_starts_ret`       | `mbedtls_md5_starts`       |
+| `mbedtls_md5_update_ret`       | `mbedtls_md5_update`       |
+| `mbedtls_md5_finish_ret`       | `mbedtls_md5_finish`       |
+| `mbedtls_md5_ret`              | `mbedtls_md5`              |
+| `mbedtls_ripemd160_starts_ret` | `mbedtls_ripemd160_starts` |
+| `mbedtls_ripemd160_update_ret` | `mbedtls_ripemd160_update` |
+| `mbedtls_ripemd160_finish_ret` | `mbedtls_ripemd160_finish` |
+| `mbedtls_ripemd160_ret`        | `mbedtls_ripemd160`        |
+| `mbedtls_sha1_starts_ret`      | `mbedtls_sha1_starts`      |
+| `mbedtls_sha1_update_ret`      | `mbedtls_sha1_update`      |
+| `mbedtls_sha1_finish_ret`      | `mbedtls_sha1_finish`      |
+| `mbedtls_sha1_ret`             | `mbedtls_sha1`             |
+| `mbedtls_sha256_starts_ret`    | `mbedtls_sha256_starts`    |
+| `mbedtls_sha256_update_ret`    | `mbedtls_sha256_update`    |
+| `mbedtls_sha256_finish_ret`    | `mbedtls_sha256_finish`    |
+| `mbedtls_sha256_ret`           | `mbedtls_sha256`           |
+| `mbedtls_sha512_starts_ret`    | `mbedtls_sha512_starts`    |
+| `mbedtls_sha512_update_ret`    | `mbedtls_sha512_update`    |
+| `mbedtls_sha512_finish_ret`    | `mbedtls_sha512_finish`    |
+| `mbedtls_sha512_ret`           | `mbedtls_sha512`           |
+
+To migrate to the this change the user can keep the `*_ret` names in their code
+and include the `compat_2.x.h` header file which holds macros with proper
+renaming or to rename those functions in their code according to the list from
+mentioned header file.
+
+### Remove the RNG parameter from RSA verify functions
+
+RSA verification functions also no longer take random generator arguments (this
+was only needed when using a private key). This affects all applications using
+the RSA verify functions.
+
+### Remove the padding parameters from `mbedtls_rsa_init()`
+
+This affects all users who use the RSA encryption, decryption, sign and
+verify APIs.
+
+The function `mbedtls_rsa_init()` no longer supports selecting the PKCS#1 v2.1
+encoding and its hash. It just selects the PKCS#1 v1.5 encoding by default. If
+you were using the PKCS#1 v2.1 encoding you now need, subsequently to the call
+to `mbedtls_rsa_init()`, to call `mbedtls_rsa_set_padding()` to set it.
+
+To choose the padding type when initializing a context, instead of
+
+```C
+    mbedtls_rsa_init(ctx, padding, hash_id);
+```
+
+use
+
+```C
+    mbedtls_rsa_init(ctx);
+    mbedtls_rsa_set_padding(ctx, padding, hash_id);
+```
+
+To use PKCS#1 v1.5 padding, instead of
+
+```C
+    mbedtls_rsa_init(ctx, MBEDTLS_RSA_PKCS_V15, <ignored>);
+```
+
+just use
+
+```C
+    mbedtls_rsa_init(ctx);
+```
+
+
+## High-level crypto
+
+Please also refer to the section [Low-level crypto](#low-level-crypto) for
+changes that could sit in either category.
+
+### Calling `mbedtls_cipher_finish()` is mandatory for all multi-part operations
+
+This only affects people who use the cipher module to perform AEAD operations
+using the multi-part API.
+
+Previously, the documentation didn't state explicitly if it was OK to call
+`mbedtls_cipher_check_tag()` or `mbedtls_cipher_write_tag()` directly after
+the last call to `mbedtls_cipher_update()` — that is, without calling
+`mbedtls_cipher_finish()` in-between. If you code was missing that call,
+please add it and be prepared to get as much as 15 bytes of output.
+
+Currently the output is always 0 bytes, but it may be more when alternative
+implementations of the underlying primitives are in use, or with future
+versions of the library.
+
+### Remove MD2, MD4, RC4, Blowfish and XTEA algorithms
+
+This change affects users of the MD2, MD4, RC4, Blowfish and XTEA algorithms.
+
+They are already niche or obsolete and most of them are weak or broken. For
+those reasons possible users should consider switching to modern and safe
+alternatives to be found in literature.
+
+### Deprecated functions were removed from cipher
+
+The functions `mbedtls_cipher_auth_encrypt()` and
+`mbedtls_cipher_auth_decrypt()` were removed. They were superseded by
+`mbedtls_cipher_auth_encrypt_ext()` and `mbedtls_cipher_auth_decrypt_ext()`
+respectively which additionally support key wrapping algorithms such as
+NIST_KW.
+
+### Extra parameter for the output buffer size
+
+The following functions now take an extra parameter indicating the size of the output buffer:
+
+* `mbedtls_ecdsa_write_signature()`, `mbedtls_ecdsa_write_signature_restartable()`
+* `mbedtls_pk_sign()`, `mbedtls_pk_sign_restartable()`
+
+The requirements for the output buffer have not changed, but passing a buffer that is too small now reliably causes the functions to return an error, rather than overflowing the buffer.
+
+### Signature functions now require the hash length to match the expected value
+
+This affects users of the PK API as well as users of the low-level API in the RSA module. Users of the PSA API or of the ECDSA module are unaffected.
+
+All the functions in the RSA module that accept a `hashlen` parameter used to
+ignore it unless the `md_alg` parameter was `MBEDTLS_MD_NONE`, indicating raw
+data was signed. The `hashlen` parameter is now always the size that is read
+from the `hash` input buffer. This length must be equal to the output size of
+the hash algorithm used when signing a hash. (The requirements when signing
+raw data are unchanged.) This affects the following functions:
+
+* `mbedtls_rsa_pkcs1_sign`, `mbedtls_rsa_pkcs1_verify`
+* `mbedtls_rsa_rsassa_pkcs1_v15_sign`, `mbedtls_rsa_rsassa_pkcs1_v15_verify`
+* `mbedtls_rsa_rsassa_pss_sign`, `mbedtls_rsa_rsassa_pss_verify`
+* `mbedtls_rsa_rsassa_pss_sign_ext`, `mbedtls_rsa_rsassa_pss_verify_ext`
+
+The signature functions in the PK module no longer accept 0 as the `hash_len` parameter. The `hash_len` parameter is now always the size that is read from the `hash` input buffer. This affects the following functions:
+
+* `mbedtls_pk_sign`, `mbedtls_pk_verify`
+* `mbedtls_pk_sign_restartable`, `mbedtls_pk_verify_restartable`
+* `mbedtls_pk_verify_ext`
+
+The migration path is to pass the correct value to those functions.
+
+### Some function parameters were made const
 
 Various functions in the PK and ASN.1 modules had a `const` qualifier added to
 some of their parameters.
@@ -19,39 +446,49 @@
 those functions. In this case, you'll need to update the type of your pointers
 in order to match the new signature.
 
-Deprecated functions were removed from hashing modules
-------------------------------------------------------
+### The RNG parameter is now mandatory for all functions that accept one
 
-Modules: MD5, SHA1, SHA256, SHA512, MD.
+This change affects all users who called a function accepting a `f_rng`
+parameter with `NULL` as the value of this argument; this is no longer
+supported.
 
-- The functions `mbedtls_xxx_starts()`, `mbedtls_xxx_update()`,
-  `mbedtls_xxx_finish()` and `mbedtls_xxx()` were removed. Please use the
-function with the same name with `_ret` appended and check the return value.
-- The function `mbedtls_md_init_ctx()` was removed; please use
-  `mbedtls_md_setup()` instead.
-- The functions `mbedtls_xxx_process()` were removed. You normally don't need
-  to call that from application code. However if you do (or if you want to
-provide your own version of that function), please use
-`mbedtls_internal_xxx_process()` instead, and check the return value.
+The changed functions are: the X.509 CRT and CSR writing functions; the PK and
+RSA sign and decrypt functions; `mbedtls_rsa_private()`; the functions in DHM
+and ECDH that compute the shared secret; the scalar multiplication functions in
+ECP.
 
-Deprecated error codes for hardware failures were removed
----------------------------------------------------------
+You now need to pass a properly seeded, cryptographically secure RNG to all
+functions that accept a `f_rng` parameter. It is of course still possible to
+pass `NULL` as the context pointer `p_rng` if your RNG function doesn't need a
+context.
 
-- The macros `MBEDTLS_ERR_xxx_FEATURE_UNSUPPORTED` from various crypto modules
-  were removed; `MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED` is now used
-instead.
-- The macros `MBEDTLS_ERR_xxx_HW_ACCEL_FAILED` from various crypto modules
-  were removed; `MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED` is now used instead.
+Alternative implementations of a module (enabled with the `MBEDTLS_module_ALT`
+configuration options) may have their own internal and are free to ignore the
+`f_rng` argument but must allow users to pass one anyway.
 
-Deprecated names for PSA constants and types were removed
----------------------------------------------------------
+### Some functions gained an RNG parameter
+
+This affects users of the following functions: `mbedtls_ecp_check_pub_priv()`,
+`mbedtls_pk_check_pair()`, `mbedtls_pk_parse_key()`, and
+`mbedtls_pk_parse_keyfile()`.
+
+You now need to pass a properly seeded, cryptographically secure RNG when
+calling these functions. It is used for blinding, a countermeasure against
+side-channel attacks.
+
+
+## PSA
+
+### Deprecated names for PSA constants and types were removed
 
 Some constants and types that were present in beta versions of the PSA Crypto
 API were removed from version 1.0 of specification. Please switch to the new
 names provided by the 1.0 specification instead.
 
-Internal / alt-focused headers were moved to a private location
-----------------------------------------------------------------
+
+## Changes that only affect alternative implementations
+
+### Internal / alt-focused headers were moved to a private location
 
 This shouldn't affect users who took care not to include headers that
 were documented as internal, despite being in the public include directory.
@@ -65,8 +502,19 @@
 function that's now in a private header, please reach out on the mailing list
 and explain your need; we'll consider adding a new API in a future version.
 
-Remove the certs module from the library
-----------------------------------------
+### CCM interface changes: impact for alternative implementations
+
+The CCM interface has changed with the addition of support for
+multi-part operations. Five new API functions have been defined:
+ `mbedtls_ccm_starts()`, `mbedtls_ccm_set_lengths()`,
+ `mbedtls_ccm_update_ad()`, `mbedtls_ccm_update()` and `mbedtls_ccm_finish()`.
+Alternative implementations of CCM (`MBEDTLS_CCM_ALT`) have now to
+implement those additional five API functions.
+
+
+## X.509
+
+### Remove the certs module from the library
 
 This should not affect production use of the library, as the certificates and
 keys included there were never suitable for production use.
@@ -76,33 +524,108 @@
 `certs.c` is out of the library there is no longer any stability guaranteed
 and it may change in incompatible ways at any time.
 
-Remove the HAVEGE module
-------------------------
+### Change the API to allow adding critical extensions to CSRs
+
+This affects applications that call the `mbedtls_x509write_csr_set_extension`
+function.
+
+The API is changed to include the parameter `critical` which enables marking an
+extension included in a CSR as critical. To get the previous behavior pass 0.
+
+### Remove the config option `MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION`
+
+This change does not affect users of the default configuration; it only affects
+users who enable this option.
+
+The X.509 standard says that implementations must reject critical extensions that
+they don't recognize, and this is what Mbed TLS does by default. This option
+allowed to continue parsing those certificates but didn't provide a convenient
+way to handle those extensions.
+
+The migration path from that option is to use the
+`mbedtls_x509_crt_parse_der_with_ext_cb()` function which is functionally
+equivalent to `mbedtls_x509_crt_parse_der()`, and/or
+`mbedtls_x509_crt_parse_der_nocopy()` but it calls the callback with every
+unsupported certificate extension and additionally the "certificate policies"
+extension if it contains any unsupported certificate policies.
+
+### Remove `MBEDTLS_X509_CHECK_*_KEY_USAGE` options from `mbedtls_config.h`
+
+This change affects users who have chosen the configuration options to disable the
+library's verification of the `keyUsage` and `extendedKeyUsage` fields of x509
+certificates.
+
+The `MBEDTLS_X509_CHECK_KEY_USAGE` and `MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE`
+configuration options are removed and the X509 code now behaves as if they were
+always enabled. It is consequently not possible anymore to disable at compile
+time the verification of the `keyUsage` and `extendedKeyUsage` fields of X509
+certificates.
+
+The verification of the `keyUsage` and `extendedKeyUsage` fields is important,
+disabling it can cause security issues and it is thus not recommended. If the
+verification is for some reason undesirable, it can still be disabled by means
+of the verification callback function passed to `mbedtls_x509_crt_verify()` (see
+the documentation of this function for more information).
+
+### Remove the `MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3` option
+
+This change does not affect users who were using the default configuration, as
+this option was already disabled by default. Also, it does not affect users who
+are working with current V3 X.509 certificates.
+
+Extensions were added in V3 of the X.509 specification, so pre-V3 certificates
+containing extensions were never compliant. Mbed TLS now rejects them with a
+parsing error in all configurations, as it did previously in the default
+configuration.
+
+If you are working with the pre-V3 certificates you need to switch to the
+current ones.
+
+### Strengthen default algorithm selection for X.509
+
+This is described in the section [Strengthen default algorithm selection for X.509 and TLS](#strengthen-default-algorithm-selection-for-x.509-and-tls).
+
+### Remove wrapper for libpkcs11-helper
 
 This doesn't affect people using the default configuration as it was already
 disabled by default.
 
-This only affects users who called the HAVEGE modules directly (not
-recommended), or users who used it through the entropy module but had it as the
-only source of entropy. If you're in that case, please declare OS or hardware
-RNG interfaces with `mbedtls_entropy_add_source()` and/or use an entropy seed
-file created securely during device provisioning. See
-<https://tls.mbed.org/kb/how-to/add-entropy-sources-to-entropy-pool> for more
-information.
+If you used to rely on this module in order to store your private keys
+securely, please have a look at the key management facilities provided by the
+PSA crypto API. If you have a use case that's not covered yet by this API,
+please reach out on the mailing list.
 
-Remove support for parsing SSLv2 ClientHello
---------------------------------------------
 
-This doesn't affect people using the default configuration as it was already
-disabled by default.
+## SSL
 
-This only affects TLS servers that have clients who send an SSLv2 ClientHello.
-These days clients are very unlikely to do that. If you have a client that
-does, please try contacting them and encouraging them to upgrade their
-software.
+### Remove support for TLS 1.0, 1.1 and DTLS 1.0
 
-Remove support for SSL 3.0
---------------------------
+This change affects users of the TLS 1.0, 1.1 and DTLS 1.0 protocols.
+
+These versions have been deprecated by RFC 8996.
+Keeping them in the library creates opportunities for misconfiguration
+and possibly downgrade attacks. More generally, more code means a larger attack
+surface, even if the code is supposedly not used.
+
+The migration path is to adopt the latest versions of the protocol.
+
+As a consequence of removing TLS 1.0, support for CBC record splitting was
+also removed, as it was a work-around for a weakness in this particular
+version. There is no migration path since the feature is no longer relevant.
+
+As a consequence of currently supporting only one version of (D)TLS (and in the
+future 1.3 which will have a different version negotiation mechanism), support
+for fallback SCSV (RFC 7507) was also removed. There is no migration path as
+it's no longer useful with TLS 1.2 and later.
+
+As a consequence of currently supporting only one version of (D)TLS (and in the
+future 1.3 which will have a different concept of ciphersuites), support for
+configuring ciphersuites separately for each version via
+`mbedtls_ssl_conf_ciphersuites_for_version()` was removed. Use
+`mbedtls_ssl_conf_ciphersuites()` to configure ciphersuites to use with (D)TLS
+1.2; in the future a different API will be added for (D)TLS 1.3.
+
+### Remove support for SSL 3.0
 
 This doesn't affect people using the default configuration as it was already
 disabled by default.
@@ -112,8 +635,17 @@
 to date. If one of your peers is in that case, please try contacting them and
 encouraging them to upgrade their software.
 
-Remove support for truncated HMAC
----------------------------------
+### Remove support for parsing SSLv2 ClientHello
+
+This doesn't affect people using the default configuration as it was already
+disabled by default.
+
+This only affects TLS servers that have clients who send an SSLv2 ClientHello.
+These days clients are very unlikely to do that. If you have a client that
+does, please try contacting them and encouraging them to upgrade their
+software.
+
+### Remove support for truncated HMAC
 
 This affects users of truncated HMAC, that is, users who called
 `mbedtls_ssl_conf_truncated_hmac( ..., MBEDTLS_SSL_TRUNC_HMAC_ENABLED)`,
@@ -123,8 +655,7 @@
 The recommended migration path for people who want minimal overhead is to use a
 CCM-8 ciphersuite.
 
-Remove support for TLS record-level compression
------------------------------------------------
+### Remove support for TLS record-level compression
 
 This doesn't affect people using the default configuration as it was already
 disabled by default.
@@ -136,8 +667,7 @@
 own compression mechanisms and are in a better position than the TLS stack to
 avoid variants of the CRIME and BREACH attacks.
 
-Remove support for TLS RC4-based ciphersuites
----------------------------------------------
+### Remove support for TLS RC4-based ciphersuites
 
 This does not affect people who used the default `mbedtls_config.h` and the default
 list of ciphersuites, as RC4-based ciphersuites were already not negotiated in
@@ -147,8 +677,7 @@
 AES-GCM, AES-CCM or ChachaPoly for example) and if your peer doesn't support
 any, encourage them to upgrade their software.
 
-Remove support for TLS single-DES ciphersuites
-----------------------------------------------
+### Remove support for TLS single-DES ciphersuites
 
 This doesn't affect people using the default configuration as it was already
 disabled by default.
@@ -157,8 +686,7 @@
 AES-GCM, AES-CCM or ChachaPoly for example) and if your peer doesn't support
 any, encourage them to upgrade their software.
 
-Remove support for TLS record-level hardware acceleration
----------------------------------------------------------
+### Remove support for TLS record-level hardware acceleration
 
 This doesn't affect people using the default configuration as it was already
 disabled by default.
@@ -167,30 +695,317 @@
 However if you did, please reach out on the mailing list and let us know about
 your use case.
 
-Remove wrapper for libpkcs11-helper
------------------------------------
-
-This doesn't affect people using the default configuration as it was already
-disabled by default.
-
-If you used to rely on this module in order to store your private keys
-securely, please have a look at the key management facilities provided by the
-PSA crypto API. If you have a use case that's not covered yet by this API,
-please reach out on the mailing list.
-
-Remove config option `MBEDTLS_SSL_DEFAULT_TICKET_LIFETIME`
-----------------------------------------------------------
+### Remove config option `MBEDTLS_SSL_DEFAULT_TICKET_LIFETIME`
 
 This doesn't affect people using the default configuration.
 
 This option has not had any effect for a long time. Please use the `lifetime`
 parameter of `mbedtls_ssl_ticket_setup()` instead.
 
-Remove helpers for the transition from Mbed TLS 1.3 to Mbed TLS 2.0
--------------------------------------------------------------------
+### Combine the `MBEDTLS_SSL_CID_PADDING_GRANULARITY` and `MBEDTLS_SSL_TLS1_3_PADDING_GRANULARITY` options
 
-This only affects people who've been using Mbed TLS since before version 2.0
-and still relied on `compat-1.3.h` in their code.
+This change affects users who modified the default `mbedtls_config.h` padding granularity
+settings, i.e. enabled at least one of the options.
 
-Please use the new names directly in your code; `scripts/rename.pl` (from any
-of the 2.x releases - no longer included in 3.0) might help you do that.
+The `mbedtls_config.h` options `MBEDTLS_SSL_CID_PADDING_GRANULARITY` and
+`MBEDTLS_SSL_TLS1_3_PADDING_GRANULARITY` were combined into one option because
+they used exactly the same padding mechanism and hence their respective padding
+granularities can be used in exactly the same way. This change simplifies the
+code maintenance.
+
+The new single option `MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY` can be used
+for both DTLS-CID and TLS 1.3.
+
+### TLS now favors faster curves over larger curves
+
+The default preference order for curves in TLS now favors resource usage (performance and memory consumption) over size. The exact order is unspecified and may change, but generally you can expect 256-bit curves to be preferred over larger curves.
+
+If you prefer a different order, call `mbedtls_ssl_conf_curves()` when configuring a TLS connection.
+
+### SSL key export interface change
+
+This affects users of the SSL key export APIs:
+```
+    mbedtls_ssl_conf_export_keys_cb()
+    mbedtls_ssl_conf_export_keys_ext_cb()
+```
+
+Those APIs have been removed and replaced by the new API
+`mbedtls_ssl_set_export_keys_cb()`. This API differs from
+the previous key export API in the following ways:
+
+- It is no longer bound to an SSL configuration, but to an
+  SSL context. This allows users to more easily identify the
+  connection an exported key belongs to.
+- It no longer exports raw keys and IV.
+- A secret type parameter has been added to identify which key
+  is being exported. For TLS 1.2, only the master secret is
+  exported, but upcoming TLS 1.3 support will add other kinds of keys.
+- The callback now specifies a void return type, rather than
+  returning an error code. It is the responsibility of the application
+  to handle failures in the key export callback, for example by
+  shutting down the TLS connection.
+
+For users which do not rely on raw keys and IV, adjusting to the new
+callback type should be straightforward — see the example programs
+`programs/ssl/ssl_client2` and `programs/ssl/ssl_server2` for callbacks
+for NSSKeylog, EAP-TLS and DTLS-SRTP.
+
+Users which require access to the raw keys used to secure application
+traffic may derive those by hand based on the master secret and the
+handshake transcript hashes which can be obtained from the raw data
+on the wire. Such users are also encouraged to reach out to the
+Mbed TLS team on the mailing list, to let the team know about their
+use case.
+
+### Remove MaximumFragmentLength (MFL) query API
+
+This affects users which use the MFL query APIs
+`mbedtls_ssl_get_{input,output}_max_frag_len()` to
+infer upper bounds on the plaintext size of incoming and
+outgoing record.
+
+Users should switch to `mbedtls_ssl_get_max_{in,out}_record_payload()`
+instead, which also provides such upper bounds but takes more factors
+than just the MFL configuration into account.
+
+### Relaxed semantics for PSK configuration
+
+This affects users which call the PSK configuration APIs
+`mbedtlsl_ssl_conf_psk()` and `mbedtls_ssl_conf_psk_opaque()`
+multiple times on the same SSL configuration.
+
+In Mbed TLS 2.x, users would observe later calls overwriting
+the effect of earlier calls, with the prevailing PSK being
+the one that has been configured last. In Mbed TLS 3.0,
+calling `mbedtls_ssl_conf_[opaque_]psk()` multiple times
+will return an error, leaving the first PSK intact.
+
+To achieve equivalent functionality when migrating to Mbed TLS 3.0,
+users calling `mbedtls_ssl_conf_[opaque_]psk()` multiple times should
+remove all but the last call, so that only one call to _either_
+`mbedtls_ssl_conf_psk()` _or_ `mbedtls_ssl_conf_psk_opaque()`
+remains.
+
+### Remove the configuration to enable weak ciphersuites in SSL / TLS
+
+This does not affect users who use the default `mbedtls_config.h`, as this option was
+already off by default.
+
+If you were using a weak cipher, please switch to any of the modern,
+recommended ciphersuites (based on AES-GCM, AES-CCM or ChachaPoly for example)
+and if your peer doesn't support any, encourage them to upgrade their software.
+
+If you were using a ciphersuite without encryption, you just have to
+enable `MBEDTLS_CIPHER_NULL_CIPHER` now.
+
+### Remove the `MBEDTLS_SSL_MAX_CONTENT_LEN` configuration option
+
+This affects users who use the `MBEDTLS_SSL_MAX_CONTENT_LEN` option to
+set the maximum length of incoming and outgoing plaintext fragments,
+which can save memory by reducing the size of the TLS I/O buffers.
+
+This option is replaced by the more fine-grained options
+`MBEDTLS_SSL_IN_CONTENT_LEN` and `MBEDTLS_SSL_OUT_CONTENT_LEN` that set
+the maximum incoming and outgoing plaintext fragment lengths, respectively.
+
+### Remove the SSL API `mbedtls_ssl_get_session_pointer()`
+
+This affects two classes of users:
+
+1. Users who manually inspect parts of the current session through
+   direct structure field access.
+
+2. Users of session resumption who query the current session
+   via `mbedtls_ssl_get_session_pointer()` prior to saving or exporting
+   it via `mbedtls_ssl_session_copy()` or `mbedtls_ssl_session_save()`,
+   respectively.
+
+Migration paths:
+
+1. Mbed TLS 3.0 does not offer a migration path for the use case 1: Like many
+   other Mbed TLS structures, the structure of `mbedtls_ssl_session` is no
+   longer part of the public API in Mbed TLS 3.0, and direct structure field
+   access is no longer supported. Please see the [section on private structure fields](#most-structure-fields-are-now-private) for more details.
+
+2. Users should replace calls to `mbedtls_ssl_get_session_pointer()` by
+   calls to `mbedtls_ssl_get_session()` as demonstrated in the example
+   program `programs/ssl/ssl_client2.c`.
+
+### Remove `MBEDTLS_SSL_DTLS_BADMAC_LIMIT` option
+
+This change does not affect users who used the default `mbedtls_config.h`, as the option
+`MBEDTLS_SSL_DTLS_BADMAC_LIMIT` was already on by default.
+
+This option was a trade-off between functionality and code size: it allowed
+users who didn't need that feature to avoid paying the cost in code size, by
+disabling it.
+
+This option is no longer present, but its functionality is now always enabled.
+
+### Deprecated functions were removed from SSL
+
+The function `mbedtls_ssl_conf_dh_param()` was removed. Please use
+`mbedtls_ssl_conf_dh_param_bin()` or `mbedtls_ssl_conf_dh_param_ctx()` instead.
+
+The function `mbedtls_ssl_get_max_frag_len()` was removed. Please use
+`mbedtls_ssl_get_max_out_record_payload()` and
+`mbedtls_ssl_get_max_in_record_payload()`
+instead.
+
+### Remove `MBEDTLS_SSL_RECORD_CHECKING` option and enable its action by default
+
+This change does not affect users who use the default `mbedtls_config.h`, as the
+option `MBEDTLS_SSL_RECORD_CHECKING` was already on by default.
+
+This option was added only to control compilation of one function,
+ `mbedtls_ssl_check_record()`, which is only useful in some specific cases, so it
+was made optional to allow users who don't need it to save some code space.
+However, the same effect can be achieved by using link-time garbage collection.
+
+Users who changed the default setting of the option need to change the config/
+build system to remove that change.
+
+### Session Cache API Change
+
+This affects users who use `mbedtls_ssl_conf_session_cache()`
+to configure a custom session cache implementation different
+from the one Mbed TLS implements in `library/ssl_cache.c`.
+
+Those users will need to modify the API of their session cache
+implementation to that of a key-value store with keys being
+session IDs and values being instances of `mbedtls_ssl_session`:
+
+```C
+typedef int mbedtls_ssl_cache_get_t( void *data,
+                                     unsigned char const *session_id,
+                                     size_t session_id_len,
+                                     mbedtls_ssl_session *session );
+typedef int mbedtls_ssl_cache_set_t( void *data,
+                                     unsigned char const *session_id,
+                                     size_t session_id_len,
+                                     const mbedtls_ssl_session *session );
+```
+
+Since the structure of `mbedtls_ssl_session` is no longer public from 3.0
+onwards, portable session cache implementations must not access fields of
+`mbedtls_ssl_session`. See the corresponding migration guide. Users that
+find themselves unable to migrate their session cache functionality without
+accessing fields of `mbedtls_ssl_session` should describe their use case
+on the Mbed TLS mailing list.
+
+### Changes in the SSL error code space
+
+This affects users manually checking for the following error codes:
+
+- `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED`
+- `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH`
+- `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE`
+- `MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN`
+- `MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE`
+- `MBEDTLS_ERR_SSL_BAD_HS_XXX`
+
+Migration paths:
+- `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE` has been removed, and
+  `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` is returned instead if the user's own certificate
+  is too large to fit into the output buffers.
+  
+  Users should check for `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` instead, and potentially
+  compare the size of their own certificate against the configured size of the output buffer to
+  understand if the error is due to an overly large certificate.
+
+- `MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN` and `MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE` have been
+  replaced by `MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE`.
+
+- All codes of the form `MBEDTLS_ERR_SSL_BAD_HS_XXX` have been replaced by various alternatives, which give more information about the type of error raised.
+
+  Users should check for the newly introduced generic error codes
+
+  * `MBEDTLS_ERR_SSL_DECODE_ERROR`
+  * `MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER`,
+  * `MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE`
+  * `MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION`
+  * `MBEDTLS_ERR_SSL_BAD_CERTIFICATE`
+  * `MBEDTLS_ERR_SSL_UNRECOGNIZED_NAME`
+  * `MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION`
+  * `MBEDTLS_ERR_SSL_NO_APPLICATION_PROTOCOL`
+
+  and the pre-existing generic error codes
+
+  * `MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE`
+  * `MBEDTLS_ERR_SSL_INTERNAL_ERROR`
+
+  instead.
+
+### Modified semantics of `mbedtls_ssl_{get,set}_session()`
+
+This affects users who call `mbedtls_ssl_get_session()` or
+`mbedtls_ssl_set_session()` multiple times on the same SSL context
+representing an established TLS 1.2 connection.
+Those users will now observe the second call to fail with
+`MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE`.
+
+Migration path:
+- Exporting the same TLS 1.2 connection multiple times via
+  `mbedtls_ssl_get_session()` leads to multiple copies of
+  the same session. This use of `mbedtls_ssl_get_session()`
+  is discouraged, and the following should be considered:
+  * If the various session copies are later loaded into
+    fresh SSL contexts via `mbedtls_ssl_set_session()`,
+    export via `mbedtls_ssl_get_session()` only once and
+    load the same session into different contexts via
+    `mbedtls_ssl_set_session()`. Since `mbedtls_ssl_set_session()`
+    makes a copy of the session that's being loaded, this
+    is functionally equivalent.
+  * If the various session copies are later serialized
+    via `mbedtls_ssl_session_save()`, export and serialize
+    the session only once via `mbedtls_ssl_get_session()` and
+    `mbedtls_ssl_session_save()` and make copies of the raw
+    data instead.
+- Calling `mbedtls_ssl_set_session()` multiple times in Mbed TLS 2.x
+  is not useful since subsequent calls overwrite the effect of previous
+  calls. Applications achieve equivalent functional behavior by
+  issuing only the very last call to `mbedtls_ssl_set_session()`.
+
+### Turn `MBEDTLS_SSL_SRV_RESPECT_CLIENT_PREFERENCE` configuration option into a runtime option
+
+This change affects users who were enabling `MBEDTLS_SSL_SRV_RESPECT_CLIENT_PREFERENCE`
+option in the `mbedtls_config.h`
+
+This option has been removed and a new function with similar functionality has
+been introduced into the SSL API.
+
+This new function `mbedtls_ssl_conf_preference_order()` can be used to
+change the preferred order of ciphersuites on the server to those used on the client,
+e.g.: `mbedtls_ssl_conf_preference_order(ssl_config, MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_CLIENT)`
+has the same effect as enabling the removed option. The default state is to use
+the server order of suites.
+
+### Strengthen default algorithm selection for X.509 and TLS
+
+The default X.509 verification profile (`mbedtls_x509_crt_profile_default`) and the default curve and hash selection in TLS have changed. They are now aligned, except that the X.509 profile only lists curves that support signature verification.
+
+Hashes and curves weaker than 255 bits (security strength less than 128 bits) are no longer accepted by default. The following hashes have been removed: SHA-1 (formerly only accepted for key exchanges but not for certificate signatures), SHA-224 (weaker hashes were already not accepted). The following curves have been removed: secp192r1, secp224r1, secp192k1, secp224k1.
+
+The compile-time options `MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_CERTIFICATES` and `MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE` are no longer available.
+
+The curve secp256k1 has also been removed from the default X.509 and TLS profiles. [RFC 8422](https://datatracker.ietf.org/doc/html/rfc8422#section-5.1.1) deprecates it in TLS, and it is very rarely used, although it is not known to be weak at the time of writing.
+
+If you still need to accept certificates signed with algorithms that have been removed from the default profile, call `mbedtls_x509_crt_verify_with_profile` instead of `mbedtls_x509_crt_verify` and pass a profile that allows the curves and hashes you want. For example, to allow SHA-224:
+```C
+mbedtls_x509_crt_profile my_profile = mbedtls_x509_crt_profile_default;
+my_profile.allowed_mds |= MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 );
+```
+
+If you still need to allow hashes and curves in TLS that have been removed from the default configuration, call `mbedtls_ssl_conf_sig_hashes()` and `mbedtls_ssl_conf_curves()` with the desired lists.
+
+### Remove 3DES ciphersuites
+
+This change does not affect users using default settings for 3DES in `mbedtls_config.h`
+because the 3DES ciphersuites were disabled by that.
+
+3DES has weaknesses/limitations and there are better alternatives, and more and
+more standard bodies are recommending against its use in TLS.
+
+The migration path here is to chose from the alternatives recommended in the
+literature, such as AES.