Start extracting ssl_compute_master()
For now just moving code around, not changing indentation. Calling convention and signature are going to be adjusted in upcoming commits.
This commit is contained in:
Manuel Pégourié-Gonnard
Jarno Lamsa
parent
8d2805c784
commit
9951b712bd
@ -1002,14 +1002,6 @@ static int ssl_populate_transform( mbedtls_ssl_context *ssl )
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const mbedtls_cipher_info_t *cipher_info;
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const mbedtls_md_info_t *md_info;
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/* cf. RFC 5246, Section 8.1:
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* "The master secret is always exactly 48 bytes in length." */
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size_t const master_secret_len = 48;
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#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
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unsigned char session_hash[48];
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#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
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mbedtls_ssl_session *session = ssl->session_negotiate;
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mbedtls_ssl_transform *transform = ssl->transform_negotiate;
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mbedtls_ssl_handshake_params *handshake = ssl->handshake;
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@ -1059,136 +1051,6 @@ static int ssl_populate_transform( mbedtls_ssl_context *ssl )
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}
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#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
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/*
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* SSLv3:
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* master =
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* MD5( premaster + SHA1( 'A' + premaster + randbytes ) ) +
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* MD5( premaster + SHA1( 'BB' + premaster + randbytes ) ) +
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* MD5( premaster + SHA1( 'CCC' + premaster + randbytes ) )
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*
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* TLSv1+:
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* master = PRF( premaster, "master secret", randbytes )[0..47]
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*/
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if( handshake->resume != 0 )
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{
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
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}
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else
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{
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/* The label for the KDF used for key expansion.
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* This is either "master secret" or "extended master secret"
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* depending on whether the Extended Master Secret extension
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* is used. */
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char const *lbl = "master secret";
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/* The salt for the KDF used for key expansion.
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* - If the Extended Master Secret extension is not used,
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* this is ClientHello.Random + ServerHello.Random
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* (see Sect. 8.1 in RFC 5246).
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* - If the Extended Master Secret extension is used,
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* this is the transcript of the handshake so far.
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* (see Sect. 4 in RFC 7627). */
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unsigned char const *salt = handshake->randbytes;
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size_t salt_len = 64;
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#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
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if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED )
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{
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) );
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lbl = "extended master secret";
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salt = session_hash;
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ssl->handshake->calc_verify( ssl, session_hash );
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#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
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if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
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{
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#if defined(MBEDTLS_SHA512_C)
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if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
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{
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salt_len = 48;
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}
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else
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#endif /* MBEDTLS_SHA512_C */
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salt_len = 32;
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}
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else
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#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
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salt_len = 36;
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MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, salt_len );
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}
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#endif /* MBEDTLS_SSL_EXTENDED_MS_ENABLED */
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#if defined(MBEDTLS_USE_PSA_CRYPTO) && \
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defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
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if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK &&
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ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
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ssl_use_opaque_psk( ssl ) == 1 )
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{
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/* Perform PSK-to-MS expansion in a single step. */
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psa_status_t status;
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psa_algorithm_t alg;
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psa_key_handle_t psk;
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psa_key_derivation_operation_t derivation =
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PSA_KEY_DERIVATION_OPERATION_INIT;
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MBEDTLS_SSL_DEBUG_MSG( 2, ( "perform PSA-based PSK-to-MS expansion" ) );
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psk = ssl->conf->psk_opaque;
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if( ssl->handshake->psk_opaque != 0 )
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psk = ssl->handshake->psk_opaque;
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if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
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alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_384);
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else
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alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256);
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status = psa_key_derivation( &derivation, psk, alg,
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salt, salt_len,
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(unsigned char const *) lbl,
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(size_t) strlen( lbl ),
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master_secret_len );
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if( status != PSA_SUCCESS )
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{
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psa_key_derivation_abort( &derivation );
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return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
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}
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status = psa_key_derivation_output_bytes( &derivation,
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session->master,
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master_secret_len );
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if( status != PSA_SUCCESS )
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{
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psa_key_derivation_abort( &derivation );
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return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
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}
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status = psa_key_derivation_abort( &derivation );
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if( status != PSA_SUCCESS )
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return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
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}
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else
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#endif
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{
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ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
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lbl, salt, salt_len,
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session->master,
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master_secret_len );
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if( ret != 0 )
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{
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MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
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return( ret );
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}
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MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret",
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handshake->premaster,
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handshake->pmslen );
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mbedtls_platform_zeroize( handshake->premaster,
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sizeof(handshake->premaster) );
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}
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}
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/*
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* Swap the client and server random values.
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*/
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@ -1715,6 +1577,156 @@ static int ssl_set_handshake_prfs( mbedtls_ssl_handshake_params *handshake,
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return( 0 );
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}
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/*
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* Compute master secret
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*/
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static int ssl_compute_master( mbedtls_ssl_context *ssl )
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{
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int ret;
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mbedtls_ssl_handshake_params *handshake = ssl->handshake;
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mbedtls_ssl_session *session = ssl->session_negotiate;
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const mbedtls_ssl_ciphersuite_t *ciphersuite_info = handshake->ciphersuite_info;
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/* cf. RFC 5246, Section 8.1:
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* "The master secret is always exactly 48 bytes in length." */
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size_t const master_secret_len = 48;
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#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
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unsigned char session_hash[48];
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#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
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/*
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* SSLv3:
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* master =
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* MD5( premaster + SHA1( 'A' + premaster + randbytes ) ) +
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* MD5( premaster + SHA1( 'BB' + premaster + randbytes ) ) +
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* MD5( premaster + SHA1( 'CCC' + premaster + randbytes ) )
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*
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* TLSv1+:
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* master = PRF( premaster, "master secret", randbytes )[0..47]
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*/
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if( handshake->resume != 0 )
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{
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
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}
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else
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{
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/* The label for the KDF used for key expansion.
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* This is either "master secret" or "extended master secret"
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* depending on whether the Extended Master Secret extension
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* is used. */
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char const *lbl = "master secret";
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/* The salt for the KDF used for key expansion.
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* - If the Extended Master Secret extension is not used,
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* this is ClientHello.Random + ServerHello.Random
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* (see Sect. 8.1 in RFC 5246).
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* - If the Extended Master Secret extension is used,
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* this is the transcript of the handshake so far.
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* (see Sect. 4 in RFC 7627). */
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unsigned char const *salt = handshake->randbytes;
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size_t salt_len = 64;
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#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
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if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED )
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{
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) );
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lbl = "extended master secret";
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salt = session_hash;
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ssl->handshake->calc_verify( ssl, session_hash );
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#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
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if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
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{
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#if defined(MBEDTLS_SHA512_C)
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if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
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{
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salt_len = 48;
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}
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else
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#endif /* MBEDTLS_SHA512_C */
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salt_len = 32;
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}
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else
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#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
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salt_len = 36;
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MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, salt_len );
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}
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#endif /* MBEDTLS_SSL_EXTENDED_MS_ENABLED */
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#if defined(MBEDTLS_USE_PSA_CRYPTO) && \
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defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
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if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK &&
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ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
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ssl_use_opaque_psk( ssl ) == 1 )
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{
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/* Perform PSK-to-MS expansion in a single step. */
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psa_status_t status;
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psa_algorithm_t alg;
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psa_key_handle_t psk;
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psa_key_derivation_operation_t derivation =
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PSA_KEY_DERIVATION_OPERATION_INIT;
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MBEDTLS_SSL_DEBUG_MSG( 2, ( "perform PSA-based PSK-to-MS expansion" ) );
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psk = ssl->conf->psk_opaque;
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if( ssl->handshake->psk_opaque != 0 )
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psk = ssl->handshake->psk_opaque;
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if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
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alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_384);
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else
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alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256);
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status = psa_key_derivation( &derivation, psk, alg,
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salt, salt_len,
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(unsigned char const *) lbl,
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(size_t) strlen( lbl ),
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master_secret_len );
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if( status != PSA_SUCCESS )
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{
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psa_key_derivation_abort( &derivation );
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return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
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}
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status = psa_key_derivation_output_bytes( &derivation,
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session->master,
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master_secret_len );
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if( status != PSA_SUCCESS )
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{
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psa_key_derivation_abort( &derivation );
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return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
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}
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status = psa_key_derivation_abort( &derivation );
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if( status != PSA_SUCCESS )
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return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
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}
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else
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#endif
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{
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ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
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lbl, salt, salt_len,
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session->master,
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master_secret_len );
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if( ret != 0 )
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{
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MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
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return( ret );
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}
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MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret",
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handshake->premaster,
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handshake->pmslen );
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mbedtls_platform_zeroize( handshake->premaster,
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sizeof(handshake->premaster) );
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}
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}
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return( 0 );
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}
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int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
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{
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@ -1731,6 +1743,13 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
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return( ret );
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}
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ret = ssl_compute_master( ssl );
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if( ret != 0 )
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{
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MBEDTLS_SSL_DEBUG_RET( 1, "ssl_compute_master", ret );
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return( ret );
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}
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return( ssl_populate_transform( ssl ) );
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}
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