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Add RFC5764 - SRTP key generation during DTLS handshake

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Signed-off-by: Johan Pascal <johan.pascal@belledonne-communications.com>
This commit is contained in:
Johan Pascal
2015-12-03 21:56:45 +01:00
parent 935b4f96f9
commit b62bb51aff
5 changed files with 449 additions and 0 deletions
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79
library/ssl_tls.c
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@@ -871,6 +871,30 @@ static int ssl_populate_transform( mbedtls_ssl_transform *transform,
(void) ssl;
#endif
#if defined(MBEDTLS_SSL_DTLS_SRTP)
/* check if we have a chosen srtp protection profile */
if (ssl->chosen_dtls_srtp_profile != MBEDTLS_SRTP_UNSET_PROFILE) {
/* derive key material for srtp session RFC5764 section 4.2 */
/* master key and master salt are respectively 128 bits and 112 bits for all currently available modes :
* SRTP_AES128_CM_HMAC_SHA1_80, SRTP_AES128_CM_HMAC_SHA1_32
* SRTP_NULL_HMAC_SHA1_80, SRTP_NULL_HMAC_SHA1_32
* So we must export 2*(128 + 112) = 480 bits
*/
ssl->dtls_srtp_keys_len = 60;
ssl->dtls_srtp_keys = (unsigned char *)mbedtls_calloc(1, ssl->dtls_srtp_keys_len);
ret = handshake->tls_prf( session->master, 48, "EXTRACTOR-dtls_srtp",
handshake->randbytes, 64, ssl->dtls_srtp_keys, ssl->dtls_srtp_keys_len );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "dtls srtp prf", ret );
return( ret );
}
}
#endif /* MBEDTLS_SSL_DTLS_SRTP */
/*
* Some data just needs copying into the structure
*/
@@ -3859,6 +3883,14 @@ int mbedtls_ssl_setup( mbedtls_ssl_context *ssl,
mbedtls_ssl_reset_in_out_pointers( ssl );
#if defined(MBEDTLS_SSL_DTLS_SRTP)
ssl->dtls_srtp_profiles_list = NULL;
ssl->dtls_srtp_profiles_list_len = 0;
ssl->chosen_dtls_srtp_profile = MBEDTLS_SRTP_UNSET_PROFILE;
ssl->dtls_srtp_keys = NULL;
ssl->dtls_srtp_keys_len = 0;
#endif
if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
goto error;
@@ -4685,6 +4717,48 @@ const char *mbedtls_ssl_get_alpn_protocol( const mbedtls_ssl_context *ssl )
}
#endif /* MBEDTLS_SSL_ALPN */
#if defined(MBEDTLS_SSL_DTLS_SRTP)
int mbedtls_ssl_set_dtls_srtp_protection_profiles( mbedtls_ssl_context *ssl, const enum mbedtls_DTLS_SRTP_protection_profiles *profiles, size_t profiles_number)
{
size_t i;
/* check in put validity : must be a list of profiles from enumeration */
/* maximum length is 4 as only 4 protection profiles are defined */
if (profiles_number>4) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
mbedtls_free(ssl->dtls_srtp_profiles_list);
ssl->dtls_srtp_profiles_list = (enum mbedtls_DTLS_SRTP_protection_profiles *)mbedtls_calloc(1, profiles_number*sizeof(enum mbedtls_DTLS_SRTP_protection_profiles));
for (i=0; i<profiles_number; i++) {
switch (profiles[i]) {
case MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_80:
case MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_32:
case MBEDTLS_SRTP_NULL_HMAC_SHA1_80:
case MBEDTLS_SRTP_NULL_HMAC_SHA1_32:
ssl->dtls_srtp_profiles_list[i] = profiles[i];
break;
default:
mbedtls_free(ssl->dtls_srtp_profiles_list);
ssl->dtls_srtp_profiles_list = NULL;
ssl->dtls_srtp_profiles_list_len = 0;
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
}
/* assign array length */
ssl->dtls_srtp_profiles_list_len = profiles_number;
return( 0 );
}
enum mbedtls_DTLS_SRTP_protection_profiles mbedtls_ssl_get_dtls_srtp_protection_profile( const mbedtls_ssl_context *ssl)
{
return( ssl->chosen_dtls_srtp_profile);
}
#endif /* MBEDTLS_SSL_DTLS_SRTP */
void mbedtls_ssl_conf_max_version( mbedtls_ssl_config *conf, int major, int minor )
{
conf->max_major_ver = major;
@@ -6782,6 +6856,11 @@ void mbedtls_ssl_free( mbedtls_ssl_context *ssl )
mbedtls_free( ssl->cli_id );
#endif
#if defined (MBEDTLS_SSL_DTLS_SRTP)
mbedtls_free( ssl->dtls_srtp_profiles_list );
mbedtls_free( ssl->dtls_srtp_keys );
#endif /* MBEDTLS_SSL_DTLS_SRTP */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= free" ) );
/* Actually clear after last debug message */