int mbedtls_cipher_write_tag( mbedtls_cipher_context_t *ctx,
unsigned char *tag, size_t tag_len )
{
if( NULL == ctx || NULL == ctx->cipher_info || NULL == tag )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( MBEDTLS_ENCRYPT != ctx->operation )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
#if defined(MBEDTLS_GCM_C)
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
return mbedtls_gcm_finish( (mbedtls_gcm_context *) ctx->cipher_ctx, tag, tag_len );
#endif
#if defined(MBEDTLS_CHACHAPOLY_C)
if ( MBEDTLS_CIPHER_CHACHA20_POLY1305 == ctx->cipher_info->type )
{
/* Don't allow truncated MAC for Poly1305 */
if ( tag_len != 16U )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
return mbedtls_chachapoly_finish( (mbedtls_chachapoly_context*) ctx->cipher_ctx,
tag );
}
#endif
return( 0 );
}
int mbedtls_cipher_check_tag( mbedtls_cipher_context_t *ctx,
const unsigned char *tag, size_t tag_len )
{
unsigned char check_tag[16];
int ret;
if( NULL == ctx || NULL == ctx->cipher_info ||
MBEDTLS_DECRYPT != ctx->operation )
{
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
#if defined(MBEDTLS_GCM_C)
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
{
if( tag_len > sizeof( check_tag ) )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( 0 != ( ret = mbedtls_gcm_finish( (mbedtls_gcm_context *) ctx->cipher_ctx,
check_tag, tag_len ) ) )
{
return( ret );
}
/* Check the tag in "constant-time" */
if( mbedtls_constant_time_memcmp( tag, check_tag, tag_len ) != 0 )
return( MBEDTLS_ERR_CIPHER_AUTH_FAILED );
return( 0 );
}
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CHACHAPOLY_C)
if ( MBEDTLS_CIPHER_CHACHA20_POLY1305 == ctx->cipher_info->type )
{
/* Don't allow truncated MAC for Poly1305 */
if ( tag_len != sizeof( check_tag ) )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
ret = mbedtls_chachapoly_finish( (mbedtls_chachapoly_context*) ctx->cipher_ctx,
check_tag );
if ( ret != 0 )
{
return( ret );
}
/* Check the tag in "constant-time" */
if( mbedtls_constant_time_memcmp( tag, check_tag, tag_len ) != 0 )
return( MBEDTLS_ERR_CIPHER_AUTH_FAILED );
return( 0 );
}
#endif /* MBEDTLS_CHACHAPOLY_C */
return( 0 );
}
int mbedtls_cipher_write_tag( mbedtls_cipher_context_t *ctx,
unsigned char *tag, size_t tag_len )
{
if( NULL == ctx || NULL == ctx->cipher_info || NULL == tag )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( MBEDTLS_ENCRYPT != ctx->operation )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
return mbedtls_gcm_finish( (mbedtls_gcm_context *) ctx->cipher_ctx, tag, tag_len );
return( 0 );
}
int mbedtls_cipher_check_tag( mbedtls_cipher_context_t *ctx,
const unsigned char *tag, size_t tag_len )
{
int ret;
if( NULL == ctx || NULL == ctx->cipher_info ||
MBEDTLS_DECRYPT != ctx->operation )
{
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
{
unsigned char check_tag[16];
size_t i;
int diff;
if( tag_len > sizeof( check_tag ) )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( 0 != ( ret = mbedtls_gcm_finish( (mbedtls_gcm_context *) ctx->cipher_ctx,
check_tag, tag_len ) ) )
{
return( ret );
}
/* Check the tag in "constant-time" */
for( diff = 0, i = 0; i < tag_len; i++ )
diff |= tag[i] ^ check_tag[i];
if( diff != 0 )
return( MBEDTLS_ERR_CIPHER_AUTH_FAILED );
return( 0 );
}
return( 0 );
}
int GCMContext::finish(State & state, mbedtls_gcm_context * context){
Stack * stack = state.stack;
if (stack->is<LUA_TNUMBER>(1)){
size_t tagLength = stack->to<int>(1);
if ((tagLength >= 4) && (tagLength <= 16)){
unsigned char * tag = new unsigned char[tagLength];
int result = mbedtls_gcm_finish(context, tag, tagLength);
if (result == 0){
stack->pushLString(std::string(reinterpret_cast<char*>(tag), tagLength));
delete[] tag;
}
else{
delete[] tag;
stack->push<int>(result);
}
return 1;
}
}
return 0;
}
