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Implement TLS 1.3 key evolution function

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Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit is contained in:
Hanno Becker 2020-08-20 13:42:46 +01:00
parent e4849d10a6
commit e9cccb440c
2 changed files with 135 additions and 0 deletions
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62
library/ssl_tls13_keys.c
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@ -285,4 +285,66 @@ int mbedtls_ssl_tls1_3_derive_secret(
dstbuf, buflen ) );
}
int mbedtls_ssl_tls1_3_evolve_secret(
mbedtls_md_type_t hash_alg,
const unsigned char *secret_old,
const unsigned char *input, size_t input_len,
unsigned char *secret_new )
{
int ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
size_t hlen, ilen;
unsigned char _secret[ MBEDTLS_MD_MAX_SIZE ] = { 0 };
unsigned char _input [ MBEDTLS_MD_MAX_SIZE ] = { 0 };
const mbedtls_md_info_t *md;
md = mbedtls_md_info_from_type( hash_alg );
if( md == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
hlen = mbedtls_md_get_size( md );
/* For non-initial runs, call Derive-Secret( ., "derived", "")
* on the old secreet. */
if( secret_old != NULL )
{
ret = mbedtls_ssl_tls1_3_derive_secret(
hash_alg,
secret_old, hlen,
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( derived ),
NULL, 0, /* context */
MBEDTLS_SSL_TLS1_3_CONTEXT_UNHASHED,
_secret, hlen );
if( ret != 0 )
goto cleanup;
}
if( input != NULL )
{
memcpy( _input, input, input_len );
ilen = input_len;
}
else
{
ilen = hlen;
}
/* HKDF-Extract takes a salt and input key material.
* The salt is the old secret, and the input key material
* is the input secret (PSK / ECDHE). */
ret = mbedtls_hkdf_extract( md,
_secret, hlen,
_input, ilen,
secret_new );
if( ret != 0 )
goto cleanup;
ret = 0;
cleanup:
mbedtls_platform_zeroize( _secret, sizeof(_secret) );
mbedtls_platform_zeroize( _input, sizeof(_input) );
return( ret );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */