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Implement TLS 1.3 key derivation function Derive-Secret

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Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit is contained in:
Hanno Becker
2020-08-21 13:27:44 +01:00
parent 19498f8fbd
commit b35d52240b
2 changed files with 87 additions and 0 deletions
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42
library/ssl_tls13_keys.c
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@ -243,4 +243,46 @@ int mbedtls_ssl_tls1_3_make_traffic_keys(
return( 0 );
}
int mbedtls_ssl_tls1_3_derive_secret(
mbedtls_md_type_t hash_alg,
const unsigned char *secret, size_t slen,
const unsigned char *label, size_t llen,
const unsigned char *ctx, size_t clen,
int context_already_hashed,
unsigned char *dstbuf, size_t buflen )
{
int ret;
unsigned char hashed_context[ MBEDTLS_MD_MAX_SIZE ];
const mbedtls_md_info_t *md;
md = mbedtls_md_info_from_type( hash_alg );
if( md == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
if( context_already_hashed == MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED )
{
ret = mbedtls_md( md, ctx, clen, hashed_context );
if( ret != 0 )
return( ret );
clen = mbedtls_md_get_size( md );
}
else
{
/* This should never happen since this function is internal
* and the code sets `context_already_hashed` correctly.
* Let's double-check nonetheless to not run at the risk
* of getting a stack overflow. */
if( clen > sizeof(hashed_context) )
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
memcpy( hashed_context, ctx, clen );
}
return( mbedtls_ssl_tls1_3_hkdf_expand_label( hash_alg,
secret, slen,
label, llen,
hashed_context, clen,
dstbuf, buflen ) );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */