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ssl_prepare_server_key_exchange(): generate a private/public key and write out the curve identifier and public key using PSA

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Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
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Przemek Stekiel 2022-03-09 15:38:24 +01:00
parent 17f452aec4
commit b6ce0b6cd8
1 changed files with 84 additions and 0 deletions
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84
library/ssl_srv.c
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@ -3107,6 +3107,89 @@ curve_matching_done:
return( ret ); return( ret );
} }
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
psa_key_attributes_t key_attributes;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
size_t ecdh_bits = 0;
uint8_t *p = ssl->out_msg + ssl->out_msglen;
const size_t header_size = 4; // curve_type, namedcurve, data length
const size_t data_length_size = 1;
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Perform PSA-based ECDH computation." ) );
/* Convert EC group to PSA key type. */
if( ( handshake->ecdh_psa_type =
PSA_KEY_TYPE_ECC_KEY_PAIR( mbedtls_ecc_group_to_psa(
(*curve)->grp_id, &ecdh_bits ) ) ) == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Could not convert ECC group to PSA." ) );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
if( ecdh_bits > 0xffff )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid ecdh_bits." ) );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
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 );
/*
* ECParameters curve_params
*
* First byte is curve_type, always named_curve
*/
*p++ = MBEDTLS_ECP_TLS_NAMED_CURVE;
/*
* Next two bytes are the namedcurve value
*/
MBEDTLS_PUT_UINT16_BE( (*curve)->tls_id, p, 0 );
p += 2;
/* Generate ECDH private key. */
status = psa_generate_key( &key_attributes,
&handshake->ecdh_psa_privkey );
if( status != PSA_SUCCESS )
{
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_generate_key", ret );
return( ret );
}
/*
* ECPoint public
*
* First byte is data length.
* It will be filled later. p holds now the data length location.
*/
/* Export the public part of the ECDH private key from PSA.
* Make one byte space for the length.
*/
status = psa_export_public_key( handshake->ecdh_psa_privkey,
p + data_length_size,
(size_t)( MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen - header_size ),
&len );
if( status != PSA_SUCCESS )
{
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_export_public_key", ret );
return( ret );
}
/* Store the length of the exported public key. */
*p = (uint8_t) len;
/* Determine full message length. */
len += header_size;
#else
if( ( ret = mbedtls_ecdh_make_params( if( ( ret = mbedtls_ecdh_make_params(
&ssl->handshake->ecdh_ctx, &len, &ssl->handshake->ecdh_ctx, &len,
ssl->out_msg + ssl->out_msglen, ssl->out_msg + ssl->out_msglen,
@ -3116,6 +3199,7 @@ curve_matching_done:
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_make_params", ret ); MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_make_params", ret );
return( ret ); return( ret );
} }
#endif
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_SERVER_SIGNATURE_ENABLED) #if defined(MBEDTLS_KEY_EXCHANGE_WITH_SERVER_SIGNATURE_ENABLED)
dig_signed = ssl->out_msg + ssl->out_msglen; dig_signed = ssl->out_msg + ssl->out_msglen;