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Merge pull request #5524 from mprse/tls_ecdh_2c

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TLS ECDH 2c: ECHDE in TLS 1.3 (client-side)
This commit is contained in:
Manuel Pégourié-Gonnard
2022-03-08 11:43:45 +01:00
committed by GitHub
parent 44311f5c98 3f076dfb6d
commit d815114f93
6 changed files with 126 additions and 92 deletions
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133
library/ssl_tls13_client.c
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@ -146,33 +146,61 @@ static int ssl_tls13_generate_and_write_ecdh_key_exchange(
unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const mbedtls_ecp_curve_info *curve_info =
mbedtls_ecp_curve_info_from_tls_id( named_group );
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
psa_key_attributes_t key_attributes;
size_t own_pubkey_len;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
size_t ecdh_bits = 0;
if( curve_info == NULL )
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Perform PSA-based ECDH computation." ) );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "offer curve %s", curve_info->name ) );
/* Convert EC group to PSA key type. */
if( ( handshake->ecdh_psa_type =
mbedtls_psa_parse_tls_ecc_group( named_group, &ecdh_bits ) ) == 0 )
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
if( ( ret = mbedtls_ecdh_setup_no_everest( &ssl->handshake->ecdh_ctx,
curve_info->grp_id ) ) != 0 )
if( ecdh_bits > 0xffff )
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
ssl->handshake->ecdh_bits = (uint16_t) ecdh_bits;
key_attributes = psa_key_attributes_init();
psa_set_key_usage_flags( &key_attributes, PSA_KEY_USAGE_DERIVE );
psa_set_key_algorithm( &key_attributes, PSA_ALG_ECDH );
psa_set_key_type( &key_attributes, handshake->ecdh_psa_type );
psa_set_key_bits( &key_attributes, handshake->ecdh_bits );
/* Generate ECDH private key. */
status = psa_generate_key( &key_attributes,
&handshake->ecdh_psa_privkey );
if( status != PSA_SUCCESS )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_setup_no_everest", ret );
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_generate_key", ret );
return( ret );
}
ret = mbedtls_ecdh_tls13_make_params( &ssl->handshake->ecdh_ctx, out_len,
buf, end - buf,
ssl->conf->f_rng, ssl->conf->p_rng );
if( ret != 0 )
/* Export the public part of the ECDH private key from PSA. */
status = psa_export_public_key( handshake->ecdh_psa_privkey,
buf, (size_t)( end - buf ),
&own_pubkey_len );
if( status != PSA_SUCCESS )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_tls13_make_params", ret );
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_export_public_key", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
MBEDTLS_DEBUG_ECDH_Q );
if( own_pubkey_len > (size_t)( end - buf ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "No space in the buffer for ECDH public key." ) );
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
*out_len = own_pubkey_len;
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
@ -273,7 +301,7 @@ static int ssl_tls13_write_key_share_ext( mbedtls_ssl_context *ssl,
/* Pointer to group */
unsigned char *group = p;
/* Length of key_exchange */
size_t key_exchange_len;
size_t key_exchange_len = 0;
/* Check there is space for header of KeyShareEntry
* - group (2 bytes)
@ -281,8 +309,7 @@ static int ssl_tls13_write_key_share_ext( mbedtls_ssl_context *ssl,
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
p += 4;
ret = ssl_tls13_generate_and_write_ecdh_key_exchange( ssl, group_id,
p, end,
ret = ssl_tls13_generate_and_write_ecdh_key_exchange( ssl, group_id, p, end,
&key_exchange_len );
p += key_exchange_len;
if( ret != 0 )
@ -333,59 +360,24 @@ cleanup:
#if defined(MBEDTLS_ECDH_C)
static int ssl_tls13_check_ecdh_params( const mbedtls_ssl_context *ssl )
{
const mbedtls_ecp_curve_info *curve_info;
mbedtls_ecp_group_id grp_id;
#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
grp_id = ssl->handshake->ecdh_ctx.grp.id;
#else
grp_id = ssl->handshake->ecdh_ctx.grp_id;
#endif
curve_info = mbedtls_ecp_curve_info_from_grp_id( grp_id );
if( curve_info == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
if( mbedtls_ssl_check_curve( ssl, grp_id ) != 0 )
return( -1 );
MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
MBEDTLS_DEBUG_ECDH_QP );
return( 0 );
}
static int ssl_tls13_read_public_ecdhe_share( mbedtls_ssl_context *ssl,
const unsigned char *buf,
size_t buf_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
uint8_t *p = (uint8_t*)buf;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
ret = mbedtls_ecdh_tls13_read_public( &ssl->handshake->ecdh_ctx,
buf, buf_len );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ecdh_tls13_read_public" ), ret );
/* Get size of the TLS opaque key_exchange field of the KeyShareEntry struct. */
uint16_t peerkey_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
/* Check if key size is consistent with given buffer length. */
if ( peerkey_len > ( buf_len - 2 ) )
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
if( ssl_tls13_check_ecdh_params( ssl ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "ssl_tls13_check_ecdh_params() failed!" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
/* Store peer's ECDH public key. */
memcpy( handshake->ecdh_psa_peerkey, p, peerkey_len );
handshake->ecdh_psa_peerkey_len = peerkey_len;
return( 0 );
}
@ -504,7 +496,16 @@ static int ssl_tls13_parse_key_share_ext( mbedtls_ssl_context *ssl,
#if defined(MBEDTLS_ECDH_C)
if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) )
{
/* Complete ECDHE key agreement */
const mbedtls_ecp_curve_info *curve_info =
mbedtls_ecp_curve_info_from_tls_id( group );
if( curve_info == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid TLS curve group id" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
ret = ssl_tls13_read_public_ecdhe_share( ssl, p, end - p );
if( ret != 0 )
return( ret );