diff --git a/BRANCHES.md b/BRANCHES.md
index fcebd1c..7fb706d 100644
--- a/BRANCHES.md
+++ b/BRANCHES.md
@@ -16,7 +16,7 @@
 also maintain ABI compatibility within LTS branches; see the next section for
 details.
 
-## Backwards Compatibility
+## Backwards Compatibility for application code
 
 We maintain API compatibility in released versions of Mbed TLS. If you have
 code that's working and secure with Mbed TLS x.y.z and does not rely on
@@ -24,6 +24,14 @@
 modification with any later release x.y'.z' with the same major version
 number, and your code will still build, be secure, and work.
 
+Note that this guarantee only applies if you either use the default
+compile-time configuration (`mbedtls/config.h`) or the same modified
+compile-time configuration. Changing compile-time configuration options can
+result in an incompatible API or ABI, although features will generally not
+affect unrelated features (for example, enabling or disabling a
+cryptographic algorithm does not break code that does not use that
+algorithm).
+
 There are rare exceptions: code that was relying on something that became
 insecure in the meantime (for example, crypto that was found to be weak) may
 need to be changed. In case security comes in conflict with backwards
@@ -42,6 +50,19 @@
 For contributors, see the [Backwards Compatibility section of
 CONTRIBUTING](CONTRIBUTING.md#backwards-compatibility).
 
+## Backward compatibility for the key store
+
+We maintain backward compatibility with previous versions of the
+PSA Crypto persistent storage since Mbed TLS 2.25.0, provided that the
+storage backend (PSA ITS implementation) is configured in a compatible way.
+We intend to maintain this backward compatibility throughout a major version
+of Mbed TLS (for example, all Mbed TLS 3.y versions will be able to read
+keys written under any Mbed TLS 3.x with x <= y).
+
+Mbed TLS 3.x can also read keys written by Mbed TLS 2.25.0 through 2.28.x
+LTS, but future major version upgrades (for example from 2.28.x/3.x to 4.y)
+may require the use of an upgrade tool.
+
 ## Current Branches
 
 The following branches are currently maintained:
diff --git a/ChangeLog.d/asn1write-0-fix b/ChangeLog.d/asn1write-0-fix
new file mode 100644
index 0000000..2e01244
--- /dev/null
+++ b/ChangeLog.d/asn1write-0-fix
@@ -0,0 +1,2 @@
+Bugfix
+   * Fix mbedtls_asn1_write_mpi() writing an incorrect encoding of 0.
diff --git a/ChangeLog.d/bug_x448.txt b/ChangeLog.d/bug_x448.txt
new file mode 100644
index 0000000..cebefc4
--- /dev/null
+++ b/ChangeLog.d/bug_x448.txt
@@ -0,0 +1,2 @@
+Bugfix
+    * Fix order value of curve x448.
diff --git a/ChangeLog.d/fix-csr_subject_commas.txt b/ChangeLog.d/fix-csr_subject_commas.txt
new file mode 100644
index 0000000..e01c9a8
--- /dev/null
+++ b/ChangeLog.d/fix-csr_subject_commas.txt
@@ -0,0 +1,3 @@
+Bugfix
+   * Fix string representation of DNs when outputting values containing commas
+     and other special characters, conforming to RFC 1779. Fixes #769.
diff --git a/ChangeLog.d/fix-windows-cmake-build-with-shared-libraries.txt b/ChangeLog.d/fix-windows-cmake-build-with-shared-libraries.txt
index 6878645..a6540a1 100644
--- a/ChangeLog.d/fix-windows-cmake-build-with-shared-libraries.txt
+++ b/ChangeLog.d/fix-windows-cmake-build-with-shared-libraries.txt
@@ -1,3 +1,3 @@
 Bugfix
-   * Fix compilation on Windows when building shared library, by setting
-     library search path to CMAKE_CURRENT_BINARY_DIR.
+   * Fix the library search path when building a shared library with CMake
+     on Windows.
diff --git a/ChangeLog.d/fix-x25519-program.txt b/ChangeLog.d/fix-x25519-program.txt
index af60465..bf5d6ac 100644
--- a/ChangeLog.d/fix-x25519-program.txt
+++ b/ChangeLog.d/fix-x25519-program.txt
@@ -1,4 +1,4 @@
 Bugfix
-   * Fix a bug in x25519 example program where the removal of
+   * Fix a bug in the x25519 example program where the removal of
      MBEDTLS_ECDH_LEGACY_CONTEXT caused the program not to run. Fixes #4901 and
      #3191.
diff --git a/ChangeLog.d/fix_some_resource_leaks.txt b/ChangeLog.d/fix_some_resource_leaks.txt
new file mode 100644
index 0000000..f8db3f2
--- /dev/null
+++ b/ChangeLog.d/fix_some_resource_leaks.txt
@@ -0,0 +1,4 @@
+Bugfix
+   * Fix resource leaks in mbedtls_pk_parse_public_key() in low
+     memory conditions.
+
diff --git a/ChangeLog.d/mbedtls_ssl_config_defaults-memleak.txt b/ChangeLog.d/mbedtls_ssl_config_defaults-memleak.txt
index d55c016..043b273 100644
--- a/ChangeLog.d/mbedtls_ssl_config_defaults-memleak.txt
+++ b/ChangeLog.d/mbedtls_ssl_config_defaults-memleak.txt
@@ -1,2 +1,2 @@
 Bugfix
-   * Fix memory leak if mbedtls_ssl_config_defaults() call is repeated
+   * Fix a memory leak if mbedtls_ssl_config_defaults() is called twice.
diff --git a/ChangeLog.d/raw-agreement-destroy-missing.txt b/ChangeLog.d/raw-agreement-destroy-missing.txt
deleted file mode 100644
index 7342b8c..0000000
--- a/ChangeLog.d/raw-agreement-destroy-missing.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-Bugfix
-   * Add missing key slot destruction calls when a raw key agreement or
-     a public key export fails in ssl_write_client_key_exchange.
diff --git a/ChangeLog.d/resumption_cid.txt b/ChangeLog.d/resumption_cid.txt
new file mode 100644
index 0000000..5c237aa
--- /dev/null
+++ b/ChangeLog.d/resumption_cid.txt
@@ -0,0 +1,5 @@
+Bugfix
+   * Fix server connection identifier setting for outgoing encrypted records
+     on DTLS 1.2 session resumption. After DTLS 1.2 session resumption with
+     connection identifier, the Mbed TLS client now properly sends the server
+     connection identifier in encrypted record headers. Fix #5872.
diff --git a/ChangeLog.d/selftest-gcc12.txt b/ChangeLog.d/selftest-gcc12.txt
new file mode 100644
index 0000000..aafa256
--- /dev/null
+++ b/ChangeLog.d/selftest-gcc12.txt
@@ -0,0 +1,2 @@
+Bugfix
+   * Silence a warning from GCC 12 in the selftest program. Fixes #5974.
diff --git a/ChangeLog.d/use-psa-ecdhe-curve.txt b/ChangeLog.d/use-psa-ecdhe-curve.txt
index cc432bd..658f88f 100644
--- a/ChangeLog.d/use-psa-ecdhe-curve.txt
+++ b/ChangeLog.d/use-psa-ecdhe-curve.txt
@@ -4,4 +4,4 @@
      client would fail to check that the curve selected by the server for
      ECDHE was indeed one that was offered. As a result, the client would
      accept any curve that it supported, even if that curve was not allowed
-     according to its configuration.
+     according to its configuration. Fixes #5291.
diff --git a/docs/architecture/mbed-crypto-storage-specification.md b/docs/architecture/mbed-crypto-storage-specification.md
index 914bca3..d630e8e 100644
--- a/docs/architecture/mbed-crypto-storage-specification.md
+++ b/docs/architecture/mbed-crypto-storage-specification.md
@@ -112,7 +112,7 @@
 The way in which the file name is constructed from the key identifier depends on the storage backend. The content of the file is described [below](#key-file-format-for-1.0.0).
 
 * Library integration: the key file name is just the key identifier as defined in the PSA crypto specification. This is a 32-bit value.
-* PSA service integration: the key file name is `(uint32_t)owner_uid << 32 | key_id` where `key_id` is the key identifier from the owner point of view and `owner_uid` (of type `int32_t`) is the calling partition identifier provided to the server by the partition manager. This is a 64-bit value.
+* PSA service integration: the key file name is `(uint64_t)owner_uid << 32 | key_id` where `key_id` is the key identifier from the owner point of view and `owner_uid` (of type `int32_t`) is the calling partition identifier provided to the server by the partition manager. This is a 64-bit value.
 
 ### Key file format for 1.0.0
 
@@ -120,7 +120,11 @@
 
 ### Nonvolatile random seed file format for 1.0.0
 
-[Identical to 0.1.0](#nonvolatile-random-seed-file-format-for-0.1.0).
+The nonvolatile random seed file contains a seed for the random generator. If present, it is rewritten at each boot as part of the random generator initialization.
+
+The file format is just the seed as a byte string with no metadata or encoding of any kind.
+
+This is unchanged since [the feature was introduced in Mbed Crypto 0.1.0](#nonvolatile-random-seed-file-format-for-0.1.0).
 
 ### File namespace on a PSA platform for 1.0.0
 
@@ -167,7 +171,21 @@
 Released in early June 2019. <br>
 Integrated in Mbed OS 5.13.
 
-Identical to [1.0.0](#mbed-crypto-1.0.0) except for some changes in the key file format.
+Changes since [1.0.0](#mbed-crypto-1.0.0):
+
+* The stdio backend for storage has been replaced by an implementation of [PSA ITS over stdio](#file-namespace-on-stdio-for-1.1.0).
+* [Some changes in the key file format](#key-file-format-for-1.1.0).
+
+### File namespace on stdio for 1.1.0
+
+Assumption: C stdio, allowing names containing lowercase letters, digits and underscores, of length up to 23.
+
+An undocumented build-time configuration value `PSA_ITS_STORAGE_PREFIX` allows storing the key files in a directory other than the current directory. This value is simply prepended to the file name (so it must end with a directory separator to put the keys in a different directory).
+
+* `PSA_ITS_STORAGE_PREFIX "tempfile.psa_its"`: used as a temporary file. Must be writable. May be overwritten or deleted if present.
+* `sprintf(PSA_ITS_STORAGE_PREFIX "%016llx.psa_its", key_id)`: a key or non-key file. The `key_id` in the name is the 64-bit file identifier, which is the [key identifier](#key-names-for-mbed-tls-2.25.0) for a key file or some reserved identifier for a non-key file (currently: only the [nonvolatile random seed](#nonvolatile-random-seed-file-format-for-1.0.0)). The contents of the file are:
+    * Magic header (8 bytes): `"PSA\0ITS\0"`
+    * File contents.
 
 ### Key file format for 1.1.0
 
@@ -314,3 +332,134 @@
     * For an opaque key (unified driver interface): driver-specific opaque key blob.
     * For an opaque key (key in a secure element): slot number (8 bytes), in platform endianness.
 * Any trailing data is rejected on load.
+
+Mbed TLS 2.25.0
+---------------
+
+Tags: `mbedtls-2.25.0`, `mbedtls-2.26.0`, `mbedtls-2.27.0`, `mbedtls-2.28.0` (continued in early 3.x releases)
+
+First released in December 2020.
+
+Note: this is the first version that is officially supported. The version number is still 0.
+
+Backward compatibility commitments: we promise backward compatibility for stored keys when Mbed TLS is upgraded from x to y if x >= 2.25 and y < 4. See [`BRANCHES.md`](../../BRANCHES.md) for more details.
+
+Supported integrations:
+
+* [PSA platform](#file-namespace-on-a-psa-platform-on-mbed-tls-2.25.0)
+* [library using PSA ITS](#file-namespace-on-its-as-a-library-on-mbed-tls-2.25.0)
+* [library using C stdio](#file-namespace-on-stdio-for-mbed-tls-2.25.0)
+
+Supported features:
+
+* [Persistent keys](#key-file-format-for-mbed-tls-2.25.0) designated by a [key identifier and owner](#key-names-for-mbed-tls-2.25.0). Keys can be:
+    * Transparent, stored in the export format.
+    * Opaque, using the unified driver interface with statically registered drivers (`MBEDTLS_PSA_CRYPTO_DRIVERS`). The driver determines the content of the opaque key blob.
+    * Opaque, using the deprecated secure element interface with dynamically registered drivers (`MBEDTLS_PSA_CRYPTO_SE_C`). The driver picks a slot number which is stored in the place of the key material.
+* [Nonvolatile random seed](#nonvolatile-random-seed-file-format-for-mbed-tls-2.25.0) on ITS only.
+
+### Changes introduced in Mbed TLS 2.25.0
+
+* The numerical encodings of `psa_key_type_t`, `psa_key_usage_t` and `psa_algorithm_t` have changed.
+
+### File namespace on a PSA platform on Mbed TLS 2.25.0
+
+Assumption: ITS provides a 64-bit file identifier namespace. The Crypto service can use arbitrary file identifiers and no other part of the system accesses the same file identifier namespace.
+
+Assumption: the owner identifier is a nonzero value of type `int32_t`.
+
+* Files 0 through 0xfffeffff: unused.
+* Files 0xffff0000 through 0xffffffff: reserved for internal use of the crypto library or crypto service. See [non-key files](#non-key-files-on-mbed-tls-2.25.0).
+* Files 0x100000000 through 0xffffffffffff: [content](#key-file-format-for-mbed-tls-2.25.0) of the [key whose identifier is the file identifier](#key-names-for-mbed-tls-2.25.0). The upper 32 bits determine the owner.
+
+### File namespace on ITS as a library on Mbed TLS 2.25.0
+
+Assumption: ITS provides a 64-bit file identifier namespace. The entity using the crypto library can use arbitrary file identifiers and no other part of the system accesses the same file identifier namespace.
+
+This is a library integration, so there is no owner. The key file identifier is identical to the key identifier.
+
+* File 0: unused.
+* Files 1 through 0xfffeffff: [content](#key-file-format-for-mbed-tls-2.25.0) of the [key whose identifier is the file identifier](#key-names-for-mbed-tls-2.25.0).
+* Files 0xffff0000 through 0xffffffff: reserved for internal use of the crypto library or crypto service. See [non-key files](#non-key-files-on-mbed-tls-2.25.0).
+* Files 0x100000000 through 0xffffffffffffffff: unused.
+
+### File namespace on stdio for Mbed TLS 2.25.0
+
+Assumption: C stdio, allowing names containing lowercase letters, digits and underscores, of length up to 23.
+
+An undocumented build-time configuration value `PSA_ITS_STORAGE_PREFIX` allows storing the key files in a directory other than the current directory. This value is simply prepended to the file name (so it must end with a directory separator to put the keys in a different directory).
+
+* `PSA_ITS_STORAGE_PREFIX "tempfile.psa_its"`: used as a temporary file. Must be writable. May be overwritten or deleted if present.
+* `sprintf(PSA_ITS_STORAGE_PREFIX "%016llx.psa_its", key_id)`: a key or non-key file. The `key_id` in the name is the 64-bit file identifier, which is the [key identifier](#key-names-for-mbed-tls-2.25.0) for a key file or some reserved identifier for a [non-key file](#non-key-files-on-mbed-tls-2.25.0). The contents of the file are:
+    * Magic header (8 bytes): `"PSA\0ITS\0"`
+    * File contents.
+
+### Key names for Mbed TLS 2.25.0
+
+Information about each key is stored in a dedicated file designated by the key identifier. In integrations where there is no concept of key owner (in particular, in library integrations), the key identifier is exactly the key identifier as defined in the PSA Cryptography API specification (`psa_key_id_t`). In integrations where there is a concept of key owner (integration into a service for example), the key identifier is made of an owner identifier (its semantics and type are integration specific) and of the key identifier (`psa_key_id_t`) from the key owner point of view.
+
+The way in which the file name is constructed from the key identifier depends on the storage backend. The content of the file is described [below](#key-file-format-for-mbed-tls-2.25.0).
+
+* Library integration: the key file name is just the key identifier as defined in the PSA crypto specification. This is a 32-bit value which must be in the range 0x00000001..0x3fffffff (`PSA_KEY_ID_USER_MIN`..`PSA_KEY_ID_USER_MAX`).
+* PSA service integration: the key file name is `(uint64_t)owner_uid << 32 | key_id` where `key_id` is the key identifier from the owner point of view and `owner_uid` (of type `int32_t`) is the calling partition identifier provided to the server by the partition manager. This is a 64-bit value.
+
+### Key file format for Mbed TLS 2.25.0
+
+All integers are encoded in little-endian order in 8-bit bytes except where otherwise indicated.
+
+The layout of a key file is:
+
+* magic (8 bytes): `"PSA\0KEY\0"`.
+* version (4 bytes): 0.
+* lifetime (4 bytes): `psa_key_lifetime_t` value.
+* type (2 bytes): `psa_key_type_t` value.
+* bits (2 bytes): `psa_key_bits_t` value.
+* policy usage flags (4 bytes): `psa_key_usage_t` value.
+* policy usage algorithm (4 bytes): `psa_algorithm_t` value.
+* policy enrollment algorithm (4 bytes): `psa_algorithm_t` value.
+* key material length (4 bytes).
+* key material:
+    * For a transparent key: output of `psa_export_key`.
+    * For an opaque key (unified driver interface): driver-specific opaque key blob.
+    * For an opaque key (key in a dynamic secure element): slot number (8 bytes), in platform endianness.
+* Any trailing data is rejected on load.
+
+### Non-key files on Mbed TLS 2.25.0
+
+File identifiers that are outside the range of persistent key identifiers are reserved for internal use by the library. The only identifiers currently in use have the owner id (top 32 bits) set to 0.
+
+* Files 0xfffffe02 through 0xfffffeff (`PSA_CRYPTO_SE_DRIVER_ITS_UID_BASE + lifetime`): dynamic secure element driver storage. The content of the file is the secure element driver's persistent data.
+* File 0xffffff52 (`PSA_CRYPTO_ITS_RANDOM_SEED_UID`): [nonvolatile random seed](#nonvolatile-random-seed-file-format-for-mbed-tls-2.25.0).
+* File 0xffffff54 (`PSA_CRYPTO_ITS_TRANSACTION_UID`): [transaction file](#transaction-file-format-for-mbed-tls-2.25.0).
+* Other files are unused and reserved for future use.
+
+### Nonvolatile random seed file format for Mbed TLS 2.25.0
+
+[Identical to Mbed Crypto 0.1.0](#nonvolatile-random-seed-file-format-for-0.1.0).
+
+### Transaction file format for Mbed TLS 2.25.0
+
+The transaction file contains data about an ongoing action that cannot be completed atomically. It exists only if there is an ongoing transaction.
+
+All integers are encoded in platform endianness.
+
+All currently existing transactions concern a key in a dynamic secure element.
+
+The layout of a transaction file is:
+
+* type (2 bytes): the [transaction type](#transaction-types-on-mbed-tls-2.25.0).
+* unused (2 bytes)
+* lifetime (4 bytes): `psa_key_lifetime_t` value that corresponds to a key in a secure element.
+* slot number (8 bytes): `psa_key_slot_number_t` value. This is the unique designation of the key for the secure element driver.
+* key identifier (4 bytes in a library integration, 8 bytes on a PSA platform): the internal representation of the key identifier. On a PSA platform, this encodes the key owner in the same way as [in file identifiers for key files](#file-namespace-on-a-psa-platform-on-mbed-tls-2.25.0)).
+
+#### Transaction types on Mbed TLS 2.25.0
+
+* 0x0001: key creation. The following locations may or may not contain data about the key that is being created:
+    * The slot in the secure element designated by the slot number.
+    * The file containing the key metadata designated by the key identifier.
+    * The driver persistent data.
+* 0x0002: key destruction. The following locations may or may not still contain data about the key that is being destroyed:
+    * The slot in the secure element designated by the slot number.
+    * The file containing the key metadata designated by the key identifier.
+    * The driver persistent data.
diff --git a/include/psa/crypto_types.h b/include/psa/crypto_types.h
index 386c7d7..8f23021 100644
--- a/include/psa/crypto_types.h
+++ b/include/psa/crypto_types.h
@@ -69,38 +69,70 @@
  */
 
 /** \brief Encoding of a key type.
+ *
+ * Values of this type are generally constructed by macros called
+ * `PSA_KEY_TYPE_xxx`.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
  */
 typedef uint16_t psa_key_type_t;
 
 /** The type of PSA elliptic curve family identifiers.
  *
+ * Values of this type are generally constructed by macros called
+ * `PSA_ECC_FAMILY_xxx`.
+ *
  * The curve identifier is required to create an ECC key using the
  * PSA_KEY_TYPE_ECC_KEY_PAIR() or PSA_KEY_TYPE_ECC_PUBLIC_KEY()
  * macros.
  *
  * Values defined by this standard will never be in the range 0x80-0xff.
  * Vendors who define additional families must use an encoding in this range.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
  */
 typedef uint8_t psa_ecc_family_t;
 
 /** The type of PSA Diffie-Hellman group family identifiers.
  *
+ * Values of this type are generally constructed by macros called
+ * `PSA_DH_FAMILY_xxx`.
+ *
  * The group identifier is required to create an Diffie-Hellman key using the
  * PSA_KEY_TYPE_DH_KEY_PAIR() or PSA_KEY_TYPE_DH_PUBLIC_KEY()
  * macros.
  *
  * Values defined by this standard will never be in the range 0x80-0xff.
  * Vendors who define additional families must use an encoding in this range.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
  */
 typedef uint8_t psa_dh_family_t;
 
 /** \brief Encoding of a cryptographic algorithm.
  *
+ * Values of this type are generally constructed by macros called
+ * `PSA_ALG_xxx`.
+ *
  * For algorithms that can be applied to multiple key types, this type
  * does not encode the key type. For example, for symmetric ciphers
  * based on a block cipher, #psa_algorithm_t encodes the block cipher
  * mode and the padding mode while the block cipher itself is encoded
  * via #psa_key_type_t.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
  */
 typedef uint32_t psa_algorithm_t;
 
@@ -142,6 +174,14 @@
  * #PSA_KEY_LIFETIME_PERSISTENT is supported if persistent storage is
  * available. Other lifetime values may be supported depending on the
  * library configuration.
+ *
+ * Values of this type are generally constructed by macros called
+ * `PSA_KEY_LIFETIME_xxx`.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
  */
 typedef uint32_t psa_key_lifetime_t;
 
@@ -173,6 +213,11 @@
  * \note Key persistence levels are 8-bit values. Key management
  *       interfaces operate on lifetimes (type ::psa_key_lifetime_t) which
  *       encode the persistence as the lower 8 bits of a 32-bit value.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
  */
 typedef uint8_t psa_key_persistence_t;
 
@@ -209,6 +254,11 @@
  * \note Key location indicators are 24-bit values. Key management
  *       interfaces operate on lifetimes (type ::psa_key_lifetime_t) which
  *       encode the location as the upper 24 bits of a 32-bit value.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
  */
 typedef uint32_t psa_key_location_t;
 
@@ -220,9 +270,27 @@
  *   #PSA_KEY_ID_VENDOR_MIN to #PSA_KEY_ID_VENDOR_MAX.
  * - 0 is reserved as an invalid key identifier.
  * - Key identifiers outside these ranges are reserved for future use.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to how values are allocated must require careful
+ *       consideration to allow backward compatibility.
  */
 typedef uint32_t psa_key_id_t;
 
+/** Encoding of key identifiers as seen inside the PSA Crypto implementation.
+ *
+ * When PSA Crypto is built as a library inside an application, this type
+ * is identical to #psa_key_id_t. When PSA Crypto is built as a service
+ * that can store keys on behalf of multiple clients, this type
+ * encodes the #psa_key_id_t value seen by each client application as
+ * well as extra information that identifies the client that owns
+ * the key.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
+*/
 #if !defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
 typedef psa_key_id_t mbedtls_svc_key_id_t;
 
@@ -246,7 +314,16 @@
  * @{
  */
 
-/** \brief Encoding of permitted usage on a key. */
+/** \brief Encoding of permitted usage on a key.
+ *
+ * Values of this type are generally constructed as bitwise-ors of macros
+ * called `PSA_KEY_USAGE_xxx`.
+ *
+ * \note Values of this type are encoded in the persistent key store.
+ *       Any changes to existing values will require bumping the storage
+ *       format version and providing a translation when reading the old
+ *       format.
+ */
 typedef uint32_t psa_key_usage_t;
 
 /**@}*/
@@ -375,7 +452,11 @@
  * @{
  */
 
-/** \brief Encoding of the step of a key derivation. */
+/** \brief Encoding of the step of a key derivation.
+ *
+ * Values of this type are generally constructed by macros called
+ * `PSA_KEY_DERIVATION_INPUT_xxx`.
+ */
 typedef uint16_t psa_key_derivation_step_t;
 
 /**@}*/
diff --git a/include/psa/crypto_values.h b/include/psa/crypto_values.h
index cd9a034..8b3a815 100644
--- a/include/psa/crypto_values.h
+++ b/include/psa/crypto_values.h
@@ -12,6 +12,11 @@
  * designations of cryptographic algorithms, and error codes returned by
  * the library.
  *
+ * Note that many of the constants defined in this file are embedded in
+ * the persistent key store, as part of key metadata (including usage
+ * policies). As a consequence, they must not be changed (unless the storage
+ * format version changes).
+ *
  * This header file only defines preprocessor macros.
  */
 /*
@@ -40,6 +45,18 @@
 
 /* PSA error codes */
 
+/* Error codes are standardized across PSA domains (framework, crypto, storage,
+ * etc.). Do not change the values in this section or even the expansions
+ * of each macro: it must be possible to `#include` both this header
+ * and some other PSA component's headers in the same C source,
+ * which will lead to duplicate definitions of the `PSA_SUCCESS` and
+ * `PSA_ERROR_xxx` macros, which is ok if and only if the macros expand
+ * to the same sequence of tokens.
+ *
+ * If you must add a new
+ * value, check with the Arm PSA framework group to pick one that other
+ * domains aren't already using. */
+
 /** The action was completed successfully. */
 #define PSA_SUCCESS ((psa_status_t)0)
 
@@ -316,6 +333,12 @@
  * @{
  */
 
+/* Note that key type values, including ECC family and DH group values, are
+ * embedded in the persistent key store, as part of key metadata. As a
+ * consequence, they must not be changed (unless the storage format version
+ * changes).
+ */
+
 /** An invalid key type value.
  *
  * Zero is not the encoding of any key type.
@@ -673,6 +696,11 @@
      1u << PSA_GET_KEY_TYPE_BLOCK_SIZE_EXPONENT(type) :                         \
      0u)
 
+/* Note that algorithm values are embedded in the persistent key store,
+ * as part of key metadata. As a consequence, they must not be changed
+ * (unless the storage format version changes).
+ */
+
 /** Vendor-defined algorithm flag.
  *
  * Algorithms defined by this standard will never have the #PSA_ALG_VENDOR_FLAG
@@ -1928,6 +1956,11 @@
  * @{
  */
 
+/* Note that location and persistence level values are embedded in the
+ * persistent key store, as part of key metadata. As a consequence, they
+ * must not be changed (unless the storage format version changes).
+ */
+
 /** The default lifetime for volatile keys.
  *
  * A volatile key only exists as long as the identifier to it is not destroyed.
@@ -2043,6 +2076,11 @@
 
 #define PSA_KEY_LOCATION_VENDOR_FLAG            ((psa_key_location_t)0x800000)
 
+/* Note that key identifier values are embedded in the
+ * persistent key store, as part of key metadata. As a consequence, they
+ * must not be changed (unless the storage format version changes).
+ */
+
 /** The null key identifier.
  */
 #define PSA_KEY_ID_NULL                         ((psa_key_id_t)0)
@@ -2154,6 +2192,11 @@
  * @{
  */
 
+/* Note that key usage flags are embedded in the
+ * persistent key store, as part of key metadata. As a consequence, they
+ * must not be changed (unless the storage format version changes).
+ */
+
 /** Whether the key may be exported.
  *
  * A public key or the public part of a key pair may always be exported
@@ -2255,6 +2298,9 @@
  * @{
  */
 
+/* Key input steps are not embedded in the persistent storage, so you can
+ * change them if needed: it's only an ABI change. */
+
 /** A secret input for key derivation.
  *
  * This should be a key of type #PSA_KEY_TYPE_DERIVE
diff --git a/library/asn1write.c b/library/asn1write.c
index d454841..afa26a6 100644
--- a/library/asn1write.c
+++ b/library/asn1write.c
@@ -133,6 +133,11 @@
     //
     len = mbedtls_mpi_size( X );
 
+    /* DER represents 0 with a sign bit (0=nonnegative) and 7 value bits, not
+     * as 0 digits. We need to end up with 020100, not with 0200. */
+    if( len == 0 )
+        len = 1;
+
     if( *p < start || (size_t)( *p - start ) < len )
         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index ff26a18..2199be6 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -755,6 +755,8 @@
     ECP_VALIDATE_RET( grp != NULL );
     mbedtls_ecp_group_free( grp );
 
+    mbedtls_ecp_group_init( grp );
+
     grp->id = id;
 
     switch( id )
diff --git a/library/pkparse.c b/library/pkparse.c
index cfc1dca..ea5c6b6 100644
--- a/library/pkparse.c
+++ b/library/pkparse.c
@@ -1463,10 +1463,16 @@
     {
         p = pem.buf;
         if( ( pk_info = mbedtls_pk_info_from_type( MBEDTLS_PK_RSA ) ) == NULL )
+        {
+            mbedtls_pem_free( &pem );
             return( MBEDTLS_ERR_PK_UNKNOWN_PK_ALG );
+        }
 
         if( ( ret = mbedtls_pk_setup( ctx, pk_info ) ) != 0 )
+        {
+            mbedtls_pem_free( &pem );
             return( ret );
+        }
 
         if ( ( ret = pk_get_rsapubkey( &p, p + pem.buflen, mbedtls_pk_rsa( *ctx ) ) ) != 0 )
             mbedtls_pk_free( ctx );
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index d7a5dac..72351c9 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2308,16 +2308,6 @@
     else
     {
         ssl->state = MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC;
-
-        if( ( ret = mbedtls_ssl_derive_keys( ssl ) ) != 0 )
-        {
-            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_derive_keys", ret );
-            mbedtls_ssl_send_alert_message(
-                ssl,
-                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
-                MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
-            return( ret );
-        }
     }
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "%s session has been resumed",
@@ -2570,6 +2560,24 @@
     }
 
     /*
+     * mbedtls_ssl_derive_keys() has to be called after the parsing of the
+     * extensions. It sets the transform data for the resumed session which in
+     * case of DTLS includes the server CID extracted from the CID extension.
+     */
+    if( ssl->handshake->resume )
+    {
+        if( ( ret = mbedtls_ssl_derive_keys( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_derive_keys", ret );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+            return( ret );
+        }
+    }
+
+    /*
      * Renegotiation security checks
      */
     if( ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
diff --git a/library/x509.c b/library/x509.c
index f21e9e6..3997ebd 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -741,7 +741,7 @@
 int mbedtls_x509_dn_gets( char *buf, size_t size, const mbedtls_x509_name *dn )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    size_t i, n;
+    size_t i, j, n;
     unsigned char c, merge = 0;
     const mbedtls_x509_name *name;
     const char *short_name = NULL;
@@ -775,17 +775,24 @@
             ret = mbedtls_snprintf( p, n, "\?\?=" );
         MBEDTLS_X509_SAFE_SNPRINTF;
 
-        for( i = 0; i < name->val.len; i++ )
+        for( i = 0, j = 0; i < name->val.len; i++, j++ )
         {
-            if( i >= sizeof( s ) - 1 )
-                break;
+            if( j >= sizeof( s ) - 1 )
+                return( MBEDTLS_ERR_X509_BUFFER_TOO_SMALL );
 
             c = name->val.p[i];
+            // Special characters requiring escaping, RFC 1779
+            if( c && strchr( ",=+<>#;\"\\", c ) )
+            {
+                if( j + 1 >= sizeof( s ) - 1 )
+                    return( MBEDTLS_ERR_X509_BUFFER_TOO_SMALL );
+                s[j++] = '\\';
+            }
             if( c < 32 || c >= 127 )
-                 s[i] = '?';
-            else s[i] = c;
+                 s[j] = '?';
+            else s[j] = c;
         }
-        s[i] = '\0';
+        s[j] = '\0';
         ret = mbedtls_snprintf( p, n, "%s", s );
         MBEDTLS_X509_SAFE_SNPRINTF;
 
diff --git a/programs/test/selftest.c b/programs/test/selftest.c
index 41d7040..393d737 100644
--- a/programs/test/selftest.c
+++ b/programs/test/selftest.c
@@ -89,7 +89,6 @@
     void *empty2 = mbedtls_calloc( 0, 1 );
     void *buffer1 = mbedtls_calloc( 1, 1 );
     void *buffer2 = mbedtls_calloc( 1, 1 );
-    uintptr_t old_buffer1;
 
     if( empty1 == NULL && empty2 == NULL )
     {
@@ -131,7 +130,6 @@
             mbedtls_printf( "  CALLOC(1): passed\n" );
     }
 
-    old_buffer1 = (uintptr_t) buffer1;
     mbedtls_free( buffer1 );
     buffer1 = mbedtls_calloc( 1, 1 );
     if( buffer1 == NULL )
@@ -143,9 +141,7 @@
     else
     {
         if( verbose )
-            mbedtls_printf( "  CALLOC(1 again): passed (%s address)\n",
-                            (uintptr_t) old_buffer1 == (uintptr_t) buffer1 ?
-                            "same" : "different" );
+            mbedtls_printf( "  CALLOC(1 again): passed\n" );
     }
 
     if( verbose )
diff --git a/scripts/abi_check.py b/scripts/abi_check.py
index f11cdf2..c228843 100755
--- a/scripts/abi_check.py
+++ b/scripts/abi_check.py
@@ -1,9 +1,10 @@
 #!/usr/bin/env python3
-"""
-This script compares the interfaces of two versions of Mbed TLS, looking
+"""This script compares the interfaces of two versions of Mbed TLS, looking
 for backward incompatibilities between two different Git revisions within
 an Mbed TLS repository. It must be run from the root of a Git working tree.
 
+### How the script works ###
+
 For the source (API) and runtime (ABI) interface compatibility, this script
 is a small wrapper around the abi-compliance-checker and abi-dumper tools,
 applying them to compare the header and library files.
@@ -20,7 +21,66 @@
 Returns 0 on success, 1 on non-compliance, and 2 if there is an error
 while running the script.
 
-You must run this test from an Mbed TLS root.
+### How to interpret non-compliance ###
+
+This script has relatively common false positives. In many scenarios, it only
+reports a pass if there is a strict textual match between the old version and
+the new version, and it reports problems where there is a sufficient semantic
+match but not a textual match. This section lists some common false positives.
+This is not an exhaustive list: in the end what matters is whether we are
+breaking a backward compatibility goal.
+
+**API**: the goal is that if an application works with the old version of the
+library, it can be recompiled against the new version and will still work.
+This is normally validated by comparing the declarations in `include/*/*.h`.
+A failure is a declaration that has disappeared or that now has a different
+type.
+
+  * It's ok to change or remove macros and functions that are documented as
+    for internal use only or as experimental.
+  * It's ok to rename function or macro parameters as long as the semantics
+    has not changed.
+  * It's ok to change or remove structure fields that are documented as
+    private.
+  * It's ok to add fields to a structure that already had private fields
+    or was documented as extensible.
+
+**ABI**: the goal is that if an application was built against the old version
+of the library, the same binary will work when linked against the new version.
+This is normally validated by comparing the symbols exported by `libmbed*.so`.
+A failure is a symbol that is no longer exported by the same library or that
+now has a different type.
+
+  * All ABI changes are acceptable if the library version is bumped
+    (see `scripts/bump_version.sh`).
+  * ABI changes that concern functions which are declared only inside the
+    library directory, and not in `include/*/*.h`, are acceptable only if
+    the function was only ever used inside the same library (libmbedcrypto,
+    libmbedx509, libmbedtls). As a counter example, if the old version
+    of libmbedtls calls mbedtls_foo() from libmbedcrypto, and the new version
+    of libmbedcrypto no longer has a compatible mbedtls_foo(), this does
+    require a version bump for libmbedcrypto.
+
+**Storage format**: the goal is to check that persistent keys stored by the
+old version can be read by the new version. This is normally validated by
+comparing the `*read*` test cases in `test_suite*storage_format*.data`.
+A failure is a storage read test case that is no longer present with the same
+function name and parameter list.
+
+  * It's ok if the same test data is present, but its presentation has changed,
+    for example if a test function is renamed or has different parameters.
+  * It's ok if redundant tests are removed.
+
+**Generated test coverage**: the goal is to check that automatically
+generated tests have as much coverage as before. This is normally validated
+by comparing the test cases that are automatically generated by a script.
+A failure is a generated test case that is no longer present with the same
+function name and parameter list.
+
+  * It's ok if the same test data is present, but its presentation has changed,
+    for example if a test function is renamed or has different parameters.
+  * It's ok if redundant tests are removed.
+
 """
 
 # Copyright The Mbed TLS Contributors
diff --git a/scripts/mbedtls_dev/psa_storage.py b/scripts/mbedtls_dev/psa_storage.py
index 45f0380..a06dce1 100644
--- a/scripts/mbedtls_dev/psa_storage.py
+++ b/scripts/mbedtls_dev/psa_storage.py
@@ -1,4 +1,9 @@
 """Knowledge about the PSA key store as implemented in Mbed TLS.
+
+Note that if you need to make a change that affects how keys are
+stored, this may indicate that the key store is changing in a
+backward-incompatible way! Think carefully about backward compatibility
+before changing how test data is constructed or validated.
 """
 
 # Copyright The Mbed TLS Contributors
@@ -146,6 +151,11 @@
         This is the content of the PSA storage file. When PSA storage is
         implemented over stdio files, this does not include any wrapping made
         by the PSA-storage-over-stdio-file implementation.
+
+        Note that if you need to make a change in this function,
+        this may indicate that the key store is changing in a
+        backward-incompatible way! Think carefully about backward
+        compatibility before making any change here.
         """
         header = self.MAGIC + self.pack('L', self.version)
         if self.version == 0:
diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index f3cba5a..49db4ca 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -937,6 +937,10 @@
 	$(MBEDTLS_CERT_REQ) output_file=$@ filename=$< subject_name="C=NL,O=PolarSSL,CN=PolarSSL Server 1" md=SHA1 force_ns_cert_type=1
 all_final += server1.req.cert_type_empty
 
+server1.req.commas.sha256: server1.key
+	$(MBEDTLS_CERT_REQ) output_file=$@ filename=$< subject_name="C=NL,O=PolarSSL\, Commas,CN=PolarSSL Server 1" md=SHA256
+all_final += server1.req.commas.sha256
+
 # server2*
 
 server2_pwd_ec = PolarSSLTest
@@ -994,7 +998,9 @@
 	$(MBEDTLS_CERT_WRITE) request_file=server1.req.sha256 issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20190210144406 not_after=20290210144406 md=SHA1 authority_identifier=0 version=3 output_file=$@
 server1.der: server1.crt
 	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
-all_final += server1.crt server1.noauthid.crt server1.crt.der
+server1.commas.crt: server1.key server1.req.commas.sha256 $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.req.commas.sha256 issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20190210144406 not_after=20290210144406 md=SHA1 version=3 output_file=$@
+all_final += server1.crt server1.noauthid.crt server1.crt.der server1.commas.crt
 
 server1.key_usage.crt: server1.key server1.req.sha256 $(test_ca_crt) $(test_ca_key_file_rsa)
 	$(MBEDTLS_CERT_WRITE) request_file=server1.req.sha256 issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20190210144406 not_after=20290210144406 md=SHA1 key_usage=digital_signature,non_repudiation,key_encipherment version=3 output_file=$@
diff --git a/tests/data_files/server1.commas.crt b/tests/data_files/server1.commas.crt
new file mode 100644
index 0000000..5acd255
--- /dev/null
+++ b/tests/data_files/server1.commas.crt
@@ -0,0 +1,20 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/data_files/server1.req.commas.sha256 b/tests/data_files/server1.req.commas.sha256
new file mode 100644
index 0000000..0287a31
--- /dev/null
+++ b/tests/data_files/server1.req.commas.sha256
@@ -0,0 +1,16 @@
+-----BEGIN CERTIFICATE REQUEST-----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+-----END CERTIFICATE REQUEST-----
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index b1a3288..7199462 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -3500,6 +3500,29 @@
             -C "parse new session ticket" \
             -c "a session has been resumed"
 
+# Tests for Session resume and extensions
+
+requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
+requires_config_enabled MBEDTLS_SSL_DTLS_CONNECTION_ID
+run_test    "Session resume and connection ID" \
+            "$P_SRV debug_level=3 cid=1 cid_val=dead dtls=1 tickets=0" \
+            "$P_CLI debug_level=3 cid=1 cid_val=beef dtls=1 tickets=0 reconnect=1" \
+            0 \
+            -c "Enable use of CID extension." \
+            -s "Enable use of CID extension." \
+            -c "client hello, adding CID extension" \
+            -s "found CID extension"           \
+            -s "Use of CID extension negotiated" \
+            -s "server hello, adding CID extension" \
+            -c "found CID extension" \
+            -c "Use of CID extension negotiated" \
+            -s "Copy CIDs into SSL transform" \
+            -c "Copy CIDs into SSL transform" \
+            -c "Peer CID (length 2 Bytes): de ad" \
+            -s "Peer CID (length 2 Bytes): be ef" \
+            -s "Use of Connection ID has been negotiated" \
+            -c "Use of Connection ID has been negotiated"
+
 # Tests for Session Resume based on session-ID and cache, DTLS
 
 requires_config_enabled MBEDTLS_SSL_CACHE_C
diff --git a/tests/suites/test_suite_asn1write.data b/tests/suites/test_suite_asn1write.data
index f844d48..725cbc2 100644
--- a/tests/suites/test_suite_asn1write.data
+++ b/tests/suites/test_suite_asn1write.data
@@ -91,8 +91,11 @@
 ASN.1 Write enum 2147483647
 mbedtls_asn1_write_enum:0x7fffffff:"0A047fffffff"
 
-#ASN.1 Write mpi 0
-#mbedtls_asn1_write_mpi:"00":"020100"
+ASN.1 Write mpi 0 (null)
+mbedtls_asn1_write_mpi:"":"020100"
+
+ASN.1 Write mpi 0 (1 limb)
+mbedtls_asn1_write_mpi:"00":"020100"
 
 ASN.1 Write mpi 1
 mbedtls_asn1_write_mpi:"01":"020101"
@@ -100,11 +103,17 @@
 ASN.1 Write mpi 0x7f
 mbedtls_asn1_write_mpi:"7f":"02017f"
 
-#ASN.1 Write mpi 0x80
-#mbedtls_asn1_write_mpi:"7f":"02020080"
+ASN.1 Write mpi 0x7f with leading 0 limb
+mbedtls_asn1_write_mpi:"00000000000000007f":"02017f"
 
-#ASN.1 Write mpi 0xff
-#mbedtls_asn1_write_mpi:"7f":"020200ff"
+ASN.1 Write mpi 0x80
+mbedtls_asn1_write_mpi:"80":"02020080"
+
+ASN.1 Write mpi 0x80 with leading 0 limb
+mbedtls_asn1_write_mpi:"000000000000000080":"02020080"
+
+ASN.1 Write mpi 0xff
+mbedtls_asn1_write_mpi:"ff":"020200ff"
 
 ASN.1 Write mpi 0x100
 mbedtls_asn1_write_mpi:"0100":"02020100"
@@ -112,17 +121,17 @@
 ASN.1 Write mpi, 127*8-1 bits
 mbedtls_asn1_write_mpi:"7f7b16e05c1537de7c41cef1a0985d6a3ced98aec28e091874cbad6b5e40a5c956258f18861c28bed8ba808259339ee34b2e509c4080149474d5d5b86093f90c475a6443fc87e1a293d4151be625d652f1c32a00a018bba10c8a2ae5b2b0ee4be64e053dce9d07ec7919526c9dfcf2ec9fc3db485caa8e5a68a2cd0a427de8":"027f7f7b16e05c1537de7c41cef1a0985d6a3ced98aec28e091874cbad6b5e40a5c956258f18861c28bed8ba808259339ee34b2e509c4080149474d5d5b86093f90c475a6443fc87e1a293d4151be625d652f1c32a00a018bba10c8a2ae5b2b0ee4be64e053dce9d07ec7919526c9dfcf2ec9fc3db485caa8e5a68a2cd0a427de8"
 
-#ASN.1 Write mpi, 127*8 bits
-#mbedtls_asn1_write_mpi:"e77b16e05c1537de7c41cef1a0985d6a3ced98aec28e091874cbad6b5e40a5c956258f18861c28bed8ba808259339ee34b2e509c4080149474d5d5b86093f90c475a6443fc87e1a293d4151be625d652f1c32a00a018bba10c8a2ae5b2b0ee4be64e053dce9d07ec7919526c9dfcf2ec9fc3db485caa8e5a68a2cd0a427de8":"028180e77b16e05c1537de7c41cef1a0985d6a3ced98aec28e091874cbad6b5e40a5c956258f18861c28bed8ba808259339ee34b2e509c4080149474d5d5b86093f90c475a6443fc87e1a293d4151be625d652f1c32a00a018bba10c8a2ae5b2b0ee4be64e053dce9d07ec7919526c9dfcf2ec9fc3db485caa8e5a68a2cd0a427de8"
+ASN.1 Write mpi, 127*8 bits
+mbedtls_asn1_write_mpi:"e77b16e05c1537de7c41cef1a0985d6a3ced98aec28e091874cbad6b5e40a5c956258f18861c28bed8ba808259339ee34b2e509c4080149474d5d5b86093f90c475a6443fc87e1a293d4151be625d652f1c32a00a018bba10c8a2ae5b2b0ee4be64e053dce9d07ec7919526c9dfcf2ec9fc3db485caa8e5a68a2cd0a427de8":"02818000e77b16e05c1537de7c41cef1a0985d6a3ced98aec28e091874cbad6b5e40a5c956258f18861c28bed8ba808259339ee34b2e509c4080149474d5d5b86093f90c475a6443fc87e1a293d4151be625d652f1c32a00a018bba10c8a2ae5b2b0ee4be64e053dce9d07ec7919526c9dfcf2ec9fc3db485caa8e5a68a2cd0a427de8"
 
 ASN.1 Write mpi, 127*8+1 bits
-mbedtls_asn1_write_mpi:"108446d68934cc1af23c4cd909884d4bd737a1890e12f5ef8bf3d807d72feffa63c0bf2633345f8b8418d144617c871a7a0277ac0150eed4b3db7f9dff21114cd0d7f282400f03c931cb00c367550e374a1ed3762a1801ca714cfc8d5aac69707ca81e0661400ed0014d97cba48f94d835dd681fc3053c51958afbf7583cf49c":"028180108446d68934cc1af23c4cd909884d4bd737a1890e12f5ef8bf3d807d72feffa63c0bf2633345f8b8418d144617c871a7a0277ac0150eed4b3db7f9dff21114cd0d7f282400f03c931cb00c367550e374a1ed3762a1801ca714cfc8d5aac69707ca81e0661400ed0014d97cba48f94d835dd681fc3053c51958afbf7583cf49c"
+mbedtls_asn1_write_mpi:"018446d68934cc1af23c4cd909884d4bd737a1890e12f5ef8bf3d807d72feffa63c0bf2633345f8b8418d144617c871a7a0277ac0150eed4b3db7f9dff21114cd0d7f282400f03c931cb00c367550e374a1ed3762a1801ca714cfc8d5aac69707ca81e0661400ed0014d97cba48f94d835dd681fc3053c51958afbf7583cf49c":"028180018446d68934cc1af23c4cd909884d4bd737a1890e12f5ef8bf3d807d72feffa63c0bf2633345f8b8418d144617c871a7a0277ac0150eed4b3db7f9dff21114cd0d7f282400f03c931cb00c367550e374a1ed3762a1801ca714cfc8d5aac69707ca81e0661400ed0014d97cba48f94d835dd681fc3053c51958afbf7583cf49c"
 
 ASN.1 Write mpi, 255*8-1 bits
 mbedtls_asn1_write_mpi:"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":"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"
 
-#ASN.1 Write mpi, 255*8 bits
-#mbedtls_asn1_write_mpi:"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":"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"
+ASN.1 Write mpi, 255*8 bits
+mbedtls_asn1_write_mpi:"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":"0282010000fbd1913fcfb652896209ad3e62f5d04a8dfc71eb1698543c52200bd7bbf3c11dd9ff57c299a2f4da172b3d5bd7e29affddf8859be7d50a45537a0df15b17af603d18803fd17134847cba78d83e64bf9fee58364d6124add0541da7bad331cd35fb48186a74bc502ddb967602401c0db02b19e5d38f09e8618fa7f6a1a3f738629baffdc63d9d70d396007d943fd64ae696e5b7e88f2c6d6ec322b461dbddd36efa91d990343b66419cf4832a22dc9ad13021185a1bf007989a50ba3bfd1152b8db899482d3ed498d1b9fae243a3cdae9530d8b29fdb684f70cdc0c9b8527265312603b405e67d59d4b1d654ddc3b7fd5515acb32440dc80903c8474a2c136c"
 
 ASN.1 Write mpi, 256*8-1 bits
 mbedtls_asn1_write_mpi:"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":"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"
@@ -191,7 +200,7 @@
 mbedtls_asn1_write_string:MBEDTLS_ASN1_OID:"41":"060141"
 
 ASN.1 Write AlgorithmIdentifier, null parameters
-mbedtls_asn1_write_algorithm_identifier:"4f4944":8:"300d06034f4944"
+mbedtls_asn1_write_algorithm_identifier:"4f4944":0:"300706034f49440500"
 
 ASN.1 Write AlgorithmIdentifier, parameters (8 bytes)
 mbedtls_asn1_write_algorithm_identifier:"4f4944":8:"300d06034f4944"
diff --git a/tests/suites/test_suite_asn1write.function b/tests/suites/test_suite_asn1write.function
index 597d6ac..5aa4cbe 100644
--- a/tests/suites/test_suite_asn1write.function
+++ b/tests/suites/test_suite_asn1write.function
@@ -16,6 +16,8 @@
 int generic_write_start_step( generic_write_data_t *data )
 {
     mbedtls_test_set_step( data->size );
+    mbedtls_free( data->output );
+    data->output = NULL;
     ASSERT_ALLOC( data->output, data->size == 0 ? 1 : data->size );
     data->end = data->output + data->size;
     data->p = data->end;
@@ -45,8 +47,6 @@
     ok = 1;
 
 exit:
-    mbedtls_free( data->output );
-    data->output = NULL;
     return( ok );
 }
 
@@ -63,13 +63,14 @@
     generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
         ret = mbedtls_asn1_write_null( &data.p, data.start );
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+        /* There's no parsing function for NULL. */
     }
 
 exit:
@@ -83,13 +84,21 @@
     generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
         ret = mbedtls_asn1_write_bool( &data.p, data.start, val );
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+#if defined(MBEDTLS_ASN1_PARSE_C)
+        if( ret >= 0 )
+        {
+            int read = 0xdeadbeef;
+            TEST_EQUAL( mbedtls_asn1_get_bool( &data.p, data.end, &read ), 0 );
+            TEST_EQUAL( val, read );
+        }
+#endif /* MBEDTLS_ASN1_PARSE_C */
     }
 
 exit:
@@ -103,13 +112,21 @@
     generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
         ret = mbedtls_asn1_write_int( &data.p, data.start, val );
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+#if defined(MBEDTLS_ASN1_PARSE_C)
+        if( ret >= 0 )
+        {
+            int read = 0xdeadbeef;
+            TEST_EQUAL( mbedtls_asn1_get_int( &data.p, data.end, &read ), 0 );
+            TEST_EQUAL( val, read );
+        }
+#endif /* MBEDTLS_ASN1_PARSE_C */
     }
 
 exit:
@@ -124,13 +141,21 @@
     generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
         ret = mbedtls_asn1_write_enum( &data.p, data.start, val );
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+#if defined(MBEDTLS_ASN1_PARSE_C)
+        if( ret >= 0 )
+        {
+            int read = 0xdeadbeef;
+            TEST_EQUAL( mbedtls_asn1_get_enum( &data.p, data.end, &read ), 0 );
+            TEST_EQUAL( val, read );
+        }
+#endif /* MBEDTLS_ASN1_PARSE_C */
     }
 
 exit:
@@ -142,25 +167,35 @@
 void mbedtls_asn1_write_mpi( data_t *val, data_t *expected )
 {
     generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
-    mbedtls_mpi mpi;
+    mbedtls_mpi mpi, read;
     int ret;
 
     mbedtls_mpi_init( &mpi );
+    mbedtls_mpi_init( &read );
     TEST_ASSERT( mbedtls_mpi_read_binary( &mpi, val->x, val->len ) == 0 );
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
         ret = mbedtls_asn1_write_mpi( &data.p, data.start, &mpi );
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+#if defined(MBEDTLS_ASN1_PARSE_C)
+        if( ret >= 0 )
+        {
+            TEST_EQUAL( mbedtls_asn1_get_mpi( &data.p, data.end, &read ), 0 );
+            TEST_EQUAL( 0, mbedtls_mpi_cmp_mpi( &mpi, &read ) );
+        }
+#endif /* MBEDTLS_ASN1_PARSE_C */
+        /* Skip some intermediate lengths, they're boring. */
         if( expected->len > 10 && data.size == 8 )
             data.size = expected->len - 2;
     }
 
 exit:
     mbedtls_mpi_free( &mpi );
+    mbedtls_mpi_free( &read );
     mbedtls_free( data.output );
 }
 /* END_CASE */
@@ -171,7 +206,7 @@
     generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
@@ -208,6 +243,8 @@
         }
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+        /* There's no parsing function for octet or character strings. */
+        /* Skip some intermediate lengths, they're boring. */
         if( expected->len > 10 && data.size == 8 )
             data.size = expected->len - 2;
     }
@@ -224,8 +261,11 @@
 {
     generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
+#if defined(MBEDTLS_ASN1_PARSE_C)
+    unsigned char *buf_complete = NULL;
+#endif /* MBEDTLS_ASN1_PARSE_C */
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
@@ -240,10 +280,69 @@
             ret -= par_len;
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+
+#if defined(MBEDTLS_ASN1_PARSE_C)
+        /* Only do a parse-back test if the parameters aren't too large for
+         * a small-heap environment. The boundary is somewhat arbitrary. */
+        if( ret >= 0 && par_len <= 1234 )
+        {
+            mbedtls_asn1_buf alg = {0, 0, NULL};
+            mbedtls_asn1_buf params = {0, 0, NULL};
+            /* The writing function doesn't write the parameters unless
+             * they're null: it only takes their length as input. But the
+             * parsing function requires the parameters to be present.
+             * Thus make up parameters. */
+            size_t data_len = data.end - data.p;
+            size_t len_complete = data_len + par_len;
+            unsigned char expected_params_tag;
+            size_t expected_params_len;
+            ASSERT_ALLOC( buf_complete, len_complete );
+            unsigned char *end_complete = buf_complete + len_complete;
+            memcpy( buf_complete, data.p, data_len );
+            if( par_len == 0 )
+            {
+                /* mbedtls_asn1_write_algorithm_identifier() wrote a NULL */
+                expected_params_tag = 0x05;
+                expected_params_len = 0;
+            }
+            else if( par_len >= 2 && par_len < 2 + 128 )
+            {
+                /* Write an OCTET STRING with a short length encoding */
+                expected_params_tag = buf_complete[data_len] = 0x04;
+                expected_params_len = par_len - 2;
+                buf_complete[data_len + 1] = (unsigned char) expected_params_len;
+            }
+            else if( par_len >= 4 + 128 && par_len < 3 + 256 * 256 )
+            {
+                /* Write an OCTET STRING with a two-byte length encoding */
+                expected_params_tag = buf_complete[data_len] = 0x04;
+                expected_params_len = par_len - 4;
+                buf_complete[data_len + 1] = 0x82;
+                buf_complete[data_len + 2] = (unsigned char) ( expected_params_len >> 8 );
+                buf_complete[data_len + 3] = (unsigned char) ( expected_params_len );
+            }
+            else
+            {
+                TEST_ASSERT( ! "Bad test data: invalid length of ASN.1 element" );
+            }
+            unsigned char *p = buf_complete;
+            TEST_EQUAL( mbedtls_asn1_get_alg( &p, end_complete,
+                                              &alg, &params ), 0 );
+            TEST_EQUAL( alg.tag, MBEDTLS_ASN1_OID );
+            ASSERT_COMPARE( alg.p, alg.len, oid->x, oid->len );
+            TEST_EQUAL( params.tag, expected_params_tag );
+            TEST_EQUAL( params.len, expected_params_len );
+            mbedtls_free( buf_complete );
+            buf_complete = NULL;
+        }
+#endif /* MBEDTLS_ASN1_PARSE_C */
     }
 
 exit:
     mbedtls_free( data.output );
+#if defined(MBEDTLS_ASN1_PARSE_C)
+    mbedtls_free( buf_complete );
+#endif /* MBEDTLS_ASN1_PARSE_C */
 }
 /* END_CASE */
 
@@ -308,18 +407,63 @@
                    const unsigned char *buf, size_t bits ) =
         ( is_named ? mbedtls_asn1_write_named_bitstring :
           mbedtls_asn1_write_bitstring );
+#if defined(MBEDTLS_ASN1_PARSE_C)
+    unsigned char *masked_bitstring = NULL;
+#endif /* MBEDTLS_ASN1_PARSE_C */
 
-    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    /* The API expects `bitstring->x` to contain `bits` bits. */
+    size_t byte_length = ( bits + 7 ) / 8;
+    TEST_ASSERT( bitstring->len >= byte_length );
+
+#if defined(MBEDTLS_ASN1_PARSE_C)
+    ASSERT_ALLOC( masked_bitstring, byte_length );
+    if( byte_length != 0 )
+    {
+        memcpy( masked_bitstring, bitstring->x, byte_length );
+        if( bits % 8 != 0 )
+            masked_bitstring[byte_length - 1] &= ~( 0xff >> ( bits % 8 ) );
+    }
+    size_t value_bits = bits;
+    if( is_named )
+    {
+        /* In a named bit string, all trailing 0 bits are removed. */
+        while( byte_length > 0 && masked_bitstring[byte_length - 1] == 0 )
+            --byte_length;
+        value_bits = 8 * byte_length;
+        if( byte_length > 0 )
+        {
+            unsigned char last_byte = masked_bitstring[byte_length - 1];
+            for( unsigned b = 1; b < 0xff && ( last_byte & b ) == 0; b <<= 1 )
+                --value_bits;
+        }
+    }
+#endif /* MBEDTLS_ASN1_PARSE_C */
+
+    for( data.size = 0; data.size <= expected->len + 1; data.size++ )
     {
         if( ! generic_write_start_step( &data ) )
             goto exit;
         ret = ( *func )( &data.p, data.start, bitstring->x, bits );
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+#if defined(MBEDTLS_ASN1_PARSE_C)
+        if( ret >= 0 )
+        {
+            mbedtls_asn1_bitstring read = {0, 0, NULL};
+            TEST_EQUAL( mbedtls_asn1_get_bitstring( &data.p, data.end,
+                                                    &read ), 0 );
+            ASSERT_COMPARE( read.p, read.len,
+                            masked_bitstring, byte_length );
+            TEST_EQUAL( read.unused_bits, 8 * byte_length - value_bits );
+        }
+#endif /* MBEDTLS_ASN1_PARSE_C */
     }
 
 exit:
     mbedtls_free( data.output );
+#if defined(MBEDTLS_ASN1_PARSE_C)
+    mbedtls_free( masked_bitstring );
+#endif /* MBEDTLS_ASN1_PARSE_C */
 }
 /* END_CASE */
 
diff --git a/tests/suites/test_suite_ecp.data b/tests/suites/test_suite_ecp.data
index 79912eb..dd46603 100644
--- a/tests/suites/test_suite_ecp.data
+++ b/tests/suites/test_suite_ecp.data
@@ -796,3 +796,55 @@
 # The first call to fix_negative in the test case of issue #4296.
 ECP fix_negative: #4296.1
 fix_negative:"8A4DD4C8B42C5EAED15FE4F4579F4CE513EC90A94010BF000000000000000000":-1:256
+
+ECP check order for SECP192R1
+depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP192R1:"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22831"
+
+ECP check order for SECP224R1
+depends_on:MBEDTLS_ECP_DP_SECP224R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP224R1:"FFFFFFFFFFFFFFFFFFFFFFFFFFFF16A2E0B8F03E13DD29455C5C2A3D"
+
+ECP check order for SECP256R1
+depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP256R1:"FFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551"
+
+ECP check order for SECP384R1
+depends_on:MBEDTLS_ECP_DP_SECP384R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP384R1:"FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC7634D81F4372DDF581A0DB248B0A77AECEC196ACCC52973"
+
+ECP check order for SECP521R1
+depends_on:MBEDTLS_ECP_DP_SECP521R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP521R1:"01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFA51868783BF2F966B7FCC0148F709A5D03BB5C9B8899C47AEBB6FB71E91386409"
+
+ECP check order for BP256R1
+depends_on:MBEDTLS_ECP_DP_BP256R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_BP256R1:"A9FB57DBA1EEA9BC3E660A909D838D718C397AA3B561A6F7901E0E82974856A7"
+
+ECP check order for BP384R1
+depends_on:MBEDTLS_ECP_DP_BP384R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_BP384R1:"8CB91E82A3386D280F5D6F7E50E641DF152F7109ED5456B31F166E6CAC0425A7CF3AB6AF6B7FC3103B883202E9046565"
+
+ECP check order for BP512R1
+depends_on:MBEDTLS_ECP_DP_BP512R1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_BP512R1:"AADD9DB8DBE9C48B3FD4E6AE33C9FC07CB308DB3B3C9D20ED6639CCA70330870553E5C414CA92619418661197FAC10471DB1D381085DDADDB58796829CA90069"
+
+ECP check order for CURVE25519
+depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_CURVE25519:"1000000000000000000000000000000014def9dea2f79cd65812631a5cf5d3ed"
+
+ECP check order for SECP192K1
+depends_on:MBEDTLS_ECP_DP_SECP192K1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP192K1:"fffffffffffffffffffffffe26f2fc170f69466a74defd8d"
+
+ECP check order for SECP224K1
+depends_on:MBEDTLS_ECP_DP_SECP224K1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP224K1:"10000000000000000000000000001dce8d2ec6184caf0a971769fb1f7"
+
+ECP check order for SECP256K1
+depends_on:MBEDTLS_ECP_DP_SECP256K1_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_SECP256K1:"fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141"
+
+ECP check order for CURVE448
+depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
+ecp_check_order:MBEDTLS_ECP_DP_CURVE448:"3fffffffffffffffffffffffffffffffffffffffffffffffffffffff7cca23e9c44edb49aed63690216cc2728dc58f552378c292ab5844f3"
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index 538c648..023f5fe 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -1297,3 +1297,27 @@
     TEST_ASSERT( mbedtls_ecp_self_test( 1 ) == 0 );
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void ecp_check_order( int id, char * expected_order_hex )
+{
+    mbedtls_ecp_group grp;
+    mbedtls_mpi expected_n;
+
+    mbedtls_ecp_group_init( &grp );
+    mbedtls_mpi_init( &expected_n );
+
+    TEST_ASSERT( mbedtls_ecp_group_load( &grp, id ) == 0 );
+    TEST_ASSERT( mbedtls_test_read_mpi( &expected_n, 16, expected_order_hex ) == 0);
+
+    // check sign bits are well-formed (i.e. 1 or -1) - see #5810
+    TEST_ASSERT( grp.N.s == -1 || grp.N.s == 1);
+    TEST_ASSERT( expected_n.s == -1 || expected_n.s == 1);
+
+    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &grp.N, &expected_n ) == 0 );
+
+exit:
+    mbedtls_ecp_group_free( &grp );
+    mbedtls_mpi_free( &expected_n );
+}
+/* END_CASE */
diff --git a/tests/suites/test_suite_psa_crypto_persistent_key.data b/tests/suites/test_suite_psa_crypto_persistent_key.data
index b250634..6d208e9 100644
--- a/tests/suites/test_suite_psa_crypto_persistent_key.data
+++ b/tests/suites/test_suite_psa_crypto_persistent_key.data
@@ -1,3 +1,8 @@
+# Note that if you need to make a change that affects how keys are
+# stored, this may indicate that the key store is changing in a
+# backward-incompatible way! Think carefully about backward compatibility
+# before changing how test data is constructed or validated.
+
 Format for storage: RSA private key
 format_storage_data_check:"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":"505341004b455900000000000100000001700004010000000000000700000006620200003082025e02010002818100af057d396ee84fb75fdbb5c2b13c7fe5a654aa8aa2470b541ee1feb0b12d25c79711531249e1129628042dbbb6c120d1443524ef4c0e6e1d8956eeb2077af12349ddeee54483bc06c2c61948cd02b202e796aebd94d3a7cbf859c2c1819c324cb82b9cd34ede263a2abffe4733f077869e8660f7d6834da53d690ef7985f6bc3020301000102818100874bf0ffc2f2a71d14671ddd0171c954d7fdbf50281e4f6d99ea0e1ebcf82faa58e7b595ffb293d1abe17f110b37c48cc0f36c37e84d876621d327f64bbe08457d3ec4098ba2fa0a319fba411c2841ed7be83196a8cdf9daa5d00694bc335fc4c32217fe0488bce9cb7202e59468b1ead119000477db2ca797fac19eda3f58c1024100e2ab760841bb9d30a81d222de1eb7381d82214407f1b975cbbfe4e1a9467fd98adbd78f607836ca5be1928b9d160d97fd45c12d6b52e2c9871a174c66b488113024100c5ab27602159ae7d6f20c3c2ee851e46dc112e689e28d5fcbbf990a99ef8a90b8bb44fd36467e7fc1789ceb663abda338652c3c73f111774902e840565927091024100b6cdbd354f7df579a63b48b3643e353b84898777b48b15f94e0bfc0567a6ae5911d57ad6409cf7647bf96264e9bd87eb95e263b7110b9a1f9f94acced0fafa4d024071195eec37e8d257decfc672b07ae639f10cbb9b0c739d0c809968d644a94e3fd6ed9287077a14583f379058f76a8aecd43c62dc8c0f41766650d725275ac4a1024100bb32d133edc2e048d463388b7be9cb4be29f4b6250be603e70e3647501c97ddde20a4e71be95fd5e71784e25aca4baf25be5738aae59bbfe1c997781447a2b24":PSA_KEY_LIFETIME_PERSISTENT:PSA_KEY_TYPE_RSA_KEY_PAIR:1024:PSA_KEY_USAGE_EXPORT:PSA_ALG_CATEGORY_ASYMMETRIC_ENCRYPTION:PSA_ALG_CATEGORY_SIGN
 
diff --git a/tests/suites/test_suite_psa_crypto_persistent_key.function b/tests/suites/test_suite_psa_crypto_persistent_key.function
index bd9b9c9..08db34a 100644
--- a/tests/suites/test_suite_psa_crypto_persistent_key.function
+++ b/tests/suites/test_suite_psa_crypto_persistent_key.function
@@ -5,6 +5,11 @@
  * on the the storage format. On the other hand, these tests treat the storage
  * subsystem as a black box, and in particular have no reliance on the
  * internals of the ITS implementation.
+ *
+ * Note that if you need to make a change that affects how files are
+ * stored, this may indicate that the key store is changing in a
+ * backward-incompatible way! Think carefully about backward compatibility
+ * before changing how test data is constructed or validated.
  */
 
 #include <stdint.h>
diff --git a/tests/suites/test_suite_psa_its.function b/tests/suites/test_suite_psa_its.function
index e16c050..12878b5 100644
--- a/tests/suites/test_suite_psa_its.function
+++ b/tests/suites/test_suite_psa_its.function
@@ -3,6 +3,11 @@
 /* This test file is specific to the ITS implementation in PSA Crypto
  * on top of stdio. It expects to know what the stdio name of a file is
  * based on its keystore name.
+ *
+ * Note that if you need to make a change that affects how files are
+ * stored, this may indicate that the key store is changing in a
+ * backward-incompatible way! Think carefully about backward compatibility
+ * before changing how test data is constructed or validated.
  */
 
 #include "../library/psa_crypto_its.h"
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index 7ac91f6..066d6e4 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -318,6 +318,10 @@
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_SHA512_C:MBEDTLS_RSA_C
 mbedtls_x509_csr_info:"data_files/server1.req.sha512":"CSR version   \: 1\nsubject name  \: C=NL, O=PolarSSL, CN=PolarSSL Server 1\nsigned using  \: RSA with SHA-512\nRSA key size  \: 2048 bits\n"
 
+X509 CSR Information RSA with SHA-256, containing commas
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_SHA256_C:MBEDTLS_RSA_C:MBEDTS_X509_INFO
+mbedtls_x509_csr_info:"data_files/server1.req.commas.sha256":"CSR version   \: 1\nsubject name  \: C=NL, O=PolarSSL\, Commas, CN=PolarSSL Server 1\nsigned using  \: RSA with SHA-256\nRSA key size  \: 2048 bits\n"
+
 X509 CSR Information EC with SHA1
 depends_on:MBEDTLS_ECDSA_C:MBEDTLS_PEM_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED:MBEDTLS_SHA1_C
 mbedtls_x509_csr_info:"data_files/server5.req.sha1":"CSR version   \: 1\nsubject name  \: C=NL, O=PolarSSL, CN=localhost\nsigned using  \: ECDSA with SHA1\nEC key size   \: 256 bits\n"
@@ -399,6 +403,30 @@
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
 mbedtls_x509_dn_gets:"data_files/server2.crt":"issuer":"C=NL, O=PolarSSL, CN=PolarSSL Test CA"
 
+X509 Get Distinguished Name #5
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+mbedtls_x509_dn_gets:"data_files/server1.commas.crt":"subject":"C=NL, O=PolarSSL\, Commas, CN=PolarSSL Server 1"
+
+X509 Get Modified DN #1
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+mbedtls_x509_dn_gets_subject_replace:"data_files/server1.crt":"Modified":"C=NL, O=Modified, CN=PolarSSL Server 1":0
+
+X509 Get Modified DN #2 Name exactly 255 bytes
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+mbedtls_x509_dn_gets_subject_replace:"data_files/server1.crt":"123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345":"C=NL, O=123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345, CN=PolarSSL Server 1":0
+
+X509 Get Modified DN #3 Name exceeds 255 bytes
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+mbedtls_x509_dn_gets_subject_replace:"data_files/server1.crt":"1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456":"":MBEDTLS_ERR_X509_BUFFER_TOO_SMALL
+
+X509 Get Modified DN #4 Name exactly 255 bytes, with comma requiring escaping
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+mbedtls_x509_dn_gets_subject_replace:"data_files/server1.crt":"1234567890,1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234":"":MBEDTLS_ERR_X509_BUFFER_TOO_SMALL
+
+X509 Get Modified DN #5 Name exactly 255 bytes, ending with comma requiring escaping
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+mbedtls_x509_dn_gets_subject_replace:"data_files/server1.crt":"12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234,":"":MBEDTLS_ERR_X509_BUFFER_TOO_SMALL
+
 X509 Time Expired #1
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_HAVE_TIME_DATE:MBEDTLS_SHA1_C
 mbedtls_x509_time_is_past:"data_files/server1.crt":"valid_from":1
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index 00b6863..77f3d23 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -768,6 +768,37 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_FS_IO:MBEDTLS_X509_CRT_PARSE_C:!MBEDTLS_X509_REMOVE_INFO */
+void mbedtls_x509_dn_gets_subject_replace( char * crt_file, char * new_subject_ou, char * result_str, int ret )
+{
+    mbedtls_x509_crt   crt;
+    char buf[2000];
+    int res = 0;
+
+    mbedtls_x509_crt_init( &crt );
+    memset( buf, 0, 2000 );
+
+    TEST_ASSERT( mbedtls_x509_crt_parse_file( &crt, crt_file ) == 0 );
+    crt.subject.next->val.p = (unsigned char *) new_subject_ou;
+    crt.subject.next->val.len = strlen( new_subject_ou );
+
+    res =  mbedtls_x509_dn_gets( buf, 2000, &crt.subject );
+
+    if ( ret != 0 )
+    {
+        TEST_ASSERT( res == ret );
+    }
+    else
+    {
+        TEST_ASSERT( res != -1 );
+        TEST_ASSERT( res != -2 );
+        TEST_ASSERT( strcmp( buf, result_str ) == 0 );
+    }
+exit:
+    mbedtls_x509_crt_free( &crt );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_FS_IO:MBEDTLS_X509_CRT_PARSE_C */
 void mbedtls_x509_time_is_past( char * crt_file, char * entity, int result )
 {
diff --git a/tests/suites/test_suite_x509write.data b/tests/suites/test_suite_x509write.data
index 87f28a7..1c1cf30 100644
--- a/tests/suites/test_suite_x509write.data
+++ b/tests/suites/test_suite_x509write.data
@@ -112,7 +112,7 @@
 
 
 X509 String to Names #1
-mbedtls_x509_string_to_names:"C=NL,O=Offspark\, Inc., OU=PolarSSL":"C=NL, O=Offspark, Inc., OU=PolarSSL":0
+mbedtls_x509_string_to_names:"C=NL,O=Offspark\, Inc., OU=PolarSSL":"C=NL, O=Offspark\, Inc., OU=PolarSSL":0
 
 X509 String to Names #2
 mbedtls_x509_string_to_names:"C=NL, O=Offspark, Inc., OU=PolarSSL":"":MBEDTLS_ERR_X509_UNKNOWN_OID