Add an EC J-PAKE KDF to transform K -> SHA256(K.X) for TLS 1.2
TLS uses it to derive the session secret. The algorithm takes a serialized
point in an uncompressed form, extracts the X coordinate and computes
SHA256 of it. It is only expected to work with P-256.
Fixes #5978.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/include/mbedtls/config_psa.h b/include/mbedtls/config_psa.h
index b84a80a..88052d2 100644
--- a/include/mbedtls/config_psa.h
+++ b/include/mbedtls/config_psa.h
@@ -228,6 +228,12 @@
#endif /* !MBEDTLS_PSA_ACCEL_ALG_TLS12_PSK_TO_MS */
#endif /* PSA_WANT_ALG_TLS12_PSK_TO_MS */
+#if defined(PSA_WANT_ALG_TLS12_ECJPAKE_TO_PMS)
+#if !defined(MBEDTLS_PSA_ACCEL_ALG_TLS12_ECJPAKE_TO_PMS)
+#define MBEDTLS_PSA_BUILTIN_ALG_TLS12_ECJPAKE_TO_PMS 1
+#endif /* !MBEDTLS_PSA_ACCEL_ALG_TLS12_ECJPAKE_TO_PMS */
+#endif /* PSA_WANT_ALG_TLS12_ECJPAKE_TO_PMS */
+
#if defined(PSA_WANT_KEY_TYPE_ECC_KEY_PAIR)
#if !defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_KEY_PAIR)
#define MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR 1
@@ -629,6 +635,8 @@
#define PSA_WANT_ALG_TLS12_PRF 1
#define MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS 1
#define PSA_WANT_ALG_TLS12_PSK_TO_MS 1
+#define MBEDTLS_PSA_BUILTIN_ALG_TLS12_ECJPAKE_TO_PMS 1
+#define PSA_WANT_ALG_TLS12_ECJPAKE_TO_PMS 1
#endif /* MBEDTLS_MD_C */
#if defined(MBEDTLS_MD5_C)
diff --git a/include/psa/crypto_config.h b/include/psa/crypto_config.h
index 991be96..8737e29 100644
--- a/include/psa/crypto_config.h
+++ b/include/psa/crypto_config.h
@@ -88,6 +88,8 @@
#define PSA_WANT_ALG_STREAM_CIPHER 1
#define PSA_WANT_ALG_TLS12_PRF 1
#define PSA_WANT_ALG_TLS12_PSK_TO_MS 1
+#define PSA_WANT_ALG_TLS12_ECJPAKE_TO_PMS 1
+
/* PBKDF2-HMAC is not yet supported via the PSA API in Mbed TLS.
* Note: when adding support, also adjust include/mbedtls/config_psa.h */
//#define PSA_WANT_ALG_XTS 1
diff --git a/include/psa/crypto_sizes.h b/include/psa/crypto_sizes.h
index 1024d6b..231ea62 100644
--- a/include/psa/crypto_sizes.h
+++ b/include/psa/crypto_sizes.h
@@ -239,6 +239,15 @@
*/
#define PSA_TLS12_PSK_TO_MS_PSK_MAX_SIZE 128
+/* The expected size of input passed to psa_tls12_ecjpake_to_pms_input,
+ * which is expected to work with P-256 curve only. */
+#define PSA_TLS12_ECJPAKE_TO_PMS_INPUT_SIZE 65
+
+/* The size of a serialized K.X coordinate to be used in
+ * psa_tls12_ecjpake_to_pms_input. This function only accepts the P-256
+ * curve. */
+#define PSA_TLS12_ECJPAKE_TO_PMS_DATA_SIZE 32
+
/** The maximum size of a block cipher. */
#define PSA_BLOCK_CIPHER_BLOCK_MAX_SIZE 16
diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
index 957b4c6..afba325 100644
--- a/include/psa/crypto_struct.h
+++ b/include/psa/crypto_struct.h
@@ -202,6 +202,12 @@
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HKDF ||
MBEDTLS_PSA_BUILTIN_ALG_HKDF_EXTRACT ||
MBEDTLS_PSA_BUILTIN_ALG_HKDF_EXPAND */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_ECJPAKE_TO_PMS)
+typedef struct
+{
+ uint8_t MBEDTLS_PRIVATE(data)[PSA_TLS12_ECJPAKE_TO_PMS_DATA_SIZE];
+} psa_tls12_ecjpake_to_pms_t;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_TLS12_ECJPAKE_TO_PMS */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
@@ -267,6 +273,9 @@
defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
psa_tls12_prf_key_derivation_t MBEDTLS_PRIVATE(tls12_prf);
#endif
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_ECJPAKE_TO_PMS)
+ psa_tls12_ecjpake_to_pms_t MBEDTLS_PRIVATE(tls12_ecjpake_to_pms);
+#endif
} MBEDTLS_PRIVATE(ctx);
};
diff --git a/include/psa/crypto_values.h b/include/psa/crypto_values.h
index 5e6e5e3..0343819 100644
--- a/include/psa/crypto_values.h
+++ b/include/psa/crypto_values.h
@@ -2021,6 +2021,14 @@
#define PSA_ALG_TLS12_PSK_TO_MS_GET_HASH(hkdf_alg) \
(PSA_ALG_CATEGORY_HASH | ((hkdf_alg) & PSA_ALG_HASH_MASK))
+/* Macro to build a KDF that takes the shared secret K (an EC point in case
+ * of EC J-PAKE) and calculates SHA256(K.X) that the rest of TLS 1.2 will
+ * use to derive the session secret. Uses PSA_ALG_SHA_256.
+ */
+#define PSA_ALG_TLS12_ECJPAKE_TO_PMS ((psa_algorithm_t)0x08000600)
+#define PSA_ALG_IS_TLS12_ECJPAKE_TO_PMS(alg) \
+ (alg == PSA_ALG_TLS12_ECJPAKE_TO_PMS)
+
/* This flag indicates whether the key derivation algorithm is suitable for
* use on low-entropy secrets such as password - these algorithms are also
* known as key stretching or password hashing schemes. These are also the