return plaintext data faster on unpadded decryption

This commit is contained in:
Andy Leiserson 2017-04-28 20:01:49 -07:00 committed by Jethro Beekman
parent b604960572
commit 79e7789d44

View file

@ -325,8 +325,10 @@ int mbedtls_cipher_update( mbedtls_cipher_context_t *ctx, const unsigned char *i
/*
* If there is not enough data for a full block, cache it.
*/
if( ( ctx->operation == MBEDTLS_DECRYPT &&
if( ( ctx->operation == MBEDTLS_DECRYPT && NULL != ctx->add_padding &&
ilen <= block_size - ctx->unprocessed_len ) ||
( ctx->operation == MBEDTLS_DECRYPT && NULL == ctx->add_padding &&
ilen < block_size - ctx->unprocessed_len ) ||
( ctx->operation == MBEDTLS_ENCRYPT &&
ilen < block_size - ctx->unprocessed_len ) )
{
@ -372,9 +374,17 @@ int mbedtls_cipher_update( mbedtls_cipher_context_t *ctx, const unsigned char *i
return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
}
/* Encryption: only cache partial blocks
* Decryption w/ padding: always keep at least one whole block
* Decryption w/o padding: only cache partial blocks
*/
copy_len = ilen % block_size;
if( copy_len == 0 && ctx->operation == MBEDTLS_DECRYPT )
if( copy_len == 0 &&
ctx->operation == MBEDTLS_DECRYPT &&
NULL != ctx->add_padding)
{
copy_len = block_size;
}
memcpy( ctx->unprocessed_data, &( input[ilen - copy_len] ),
copy_len );