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/**
* \file
* \author Egor Tensin <Egor.Tensin@gmail.com>
* \date 2015
* \copyright This file is licensed under the terms of the MIT License.
* See LICENSE.txt for details.
*/
#include <aesni/all.h>
#include <stdlib.h>
#include <string.h>
static unsigned char FULL_BLOCK_PADDING[16] = { 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16 };
size_t aes128ecb_encrypt_buffer(
const unsigned char* src,
size_t src_size,
unsigned char* dest,
Aes128KeySchedule* key_schedule)
{
size_t rem_size = src_size % 16;
size_t padding_size = 16 - rem_size;
size_t dest_size = src_size + padding_size;
if (dest == NULL)
return dest_size;
size_t src_len = src_size / 16;
for (size_t i = 0; i < src_len; ++i, src += 16, dest += 16)
{
AesBlock128 plaintext = load_aes_block128(src);
AesBlock128 ciphertext = aes128ecb_encrypt_block(plaintext, key_schedule);
store_aes_block128(ciphertext, dest);
}
unsigned char padding[16];
if (rem_size == 0)
{
memcpy(padding, FULL_BLOCK_PADDING, 16);
}
else
{
memcpy(padding, src, rem_size);
memset(padding + rem_size, padding_size, padding_size);
}
AesBlock128 plaintext = load_aes_block128(padding);
AesBlock128 ciphertext = aes128ecb_encrypt_block(plaintext, key_schedule);
store_aes_block128(ciphertext, dest);
return dest_size;
}
static unsigned char get_padding_size(const unsigned char* padding)
{
if (padding[15] < 0x01 || padding[15] > 0x10)
return 0;
for (int i = 16 - padding[15]; i < 15; ++i)
if (padding[i] != padding[15])
return 0;
return padding[15];
}
size_t aes128ecb_decrypt_buffer(
const unsigned char* src,
size_t src_size,
unsigned char* dest,
Aes128KeySchedule* inverted_schedule)
{
size_t dest_size = src_size;
if (dest == NULL)
return dest_size;
size_t src_len = src_size / 16;
for (size_t i = 0; i < src_len - 1; ++i, src += 16, dest += 16)
{
AesBlock128 ciphertext = load_aes_block128(src);
AesBlock128 plaintext = aes128ecb_decrypt_block(ciphertext, inverted_schedule);
store_aes_block128(plaintext, dest);
}
AesBlock128 ciphertext = load_aes_block128(src);
AesBlock128 plaintext = aes128ecb_decrypt_block(ciphertext, inverted_schedule);
unsigned char padding[16];
store_aes_block128(plaintext, padding);
unsigned char padding_size = get_padding_size(padding);
if (padding_size == 0)
{
return dest_size - 16;
}
else
{
memcpy(dest, padding, 16 - padding_size);
return dest_size - padding_size;
}
}
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