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tls13: add handshake key schedule

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Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu 2021-09-09 17:14:45 +08:00
parent 61e35e0047
commit a0650ebb9d
2 changed files with 111 additions and 1 deletions
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92
library/ssl_tls13_keys.c
View File

@ -963,4 +963,96 @@ exit:
return( ret );
}
static int ssl_tls1_3_complete_ephemeral_secret( mbedtls_ssl_context *ssl,
unsigned char *secret,
size_t secret_len,
unsigned char **actual_secret,
size_t *actual_len )
{
int ret = 0;
*actual_secret = NULL;
*actual_len = 0;
/*
* Compute ECDHE secret for second stage of secret evolution.
*/
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED)
if( mbedtls_ssl_tls1_3_some_ephemeral_enabled( ssl ) )
{
if( mbedtls_ssl_tls13_named_group_is_ecdhe(
ssl->handshake->offered_group_id ) )
{
#if defined(MBEDTLS_ECDH_C)
ret = mbedtls_ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
actual_len, secret, secret_len,
ssl->conf->f_rng,
ssl->conf->p_rng );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
return( ret );
}
*actual_secret = secret;
#endif /* MBEDTLS_ECDH_C */
}
else if( mbedtls_ssl_tls13_named_group_is_dhe(
ssl->handshake->offered_group_id ) )
{
/* TODO: Not supported yet */
}
}
#else
((void) ssl);
((void) secret);
((void) secret_len);
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED */
return( ret );
}
int mbedtls_ssl_tls1_3_key_schedule_stage_handshake( mbedtls_ssl_context *ssl )
{
int ret = 0;
mbedtls_md_type_t const md_type = ssl->handshake->ciphersuite_info->mac;
#if defined(MBEDTLS_DEBUG_C)
mbedtls_md_info_t const * const md_info = mbedtls_md_info_from_type( md_type );
size_t const md_size = mbedtls_md_get_size( md_info );
#endif /* MBEDTLS_DEBUG_C */
unsigned char *ephemeral;
size_t ephemeral_len;
unsigned char ecdhe[66]; /* TODO: Magic constant! */
/* Finalize calculation of ephemeral input to key schedule, if present. */
ret = ssl_tls1_3_complete_ephemeral_secret( ssl, ecdhe, sizeof( ecdhe ),
&ephemeral, &ephemeral_len );
if( ret != 0 )
return( ret );
/*
* Compute HandshakeSecret
*/
ret = mbedtls_ssl_tls1_3_evolve_secret( md_type,
ssl->handshake->tls1_3_master_secrets.early,
ephemeral, ephemeral_len,
ssl->handshake->tls1_3_master_secrets.handshake );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_evolve_secret", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_BUF( 4, "Handshake secret",
ssl->handshake->tls1_3_master_secrets.handshake, md_size );
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED)
mbedtls_platform_zeroize( ecdhe, sizeof( ecdhe ) );
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED */
return( 0 );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */

20
library/ssl_tls13_keys.h
View File

@ -532,12 +532,30 @@ int mbedtls_ssl_tls13_populate_transform( mbedtls_ssl_transform *transform,
*/
int mbedtls_ssl_tls1_3_key_schedule_stage_early( mbedtls_ssl_context *ssl );
/**
* \brief Transition into handshake stage of TLS 1.3 key schedule.
*
* The TLS 1.3 key schedule can be viewed as a simple state machine
* with states Initial -> Early -> Handshake -> Application, and
* this function represents the Early -> Handshake transition.
*
* In the handshake stage, mbedtls_ssl_tls1_3_generate_handshake_keys()
* can be used to derive the handshake traffic keys.
*
* \param ssl The SSL context to operate on. This must be in key schedule
* stage \c Early.
*
* \returns \c 0 on success.
* \returns A negative error code on failure.
*/
int mbedtls_ssl_tls1_3_key_schedule_stage_handshake( mbedtls_ssl_context *ssl );
/**
* \brief Compute TLS 1.3 handshake traffic keys.
*
* \param ssl The SSL context to operate on. This must be in
* key schedule stage \c Handshake, see
* mbedtls_ssl_tls13_key_schedule_stage_handshake().
* mbedtls_ssl_tls1_3_key_schedule_stage_handshake().
* \param traffic_keys The address at which to store the handshake traffic key
* keys. This must be writable but may be uninitialized.
*