aes-cbc.c

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/*
 * AES-128 CBC
 *
 * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "aes.h"
#include "aes_wrap.h"

int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
{
        void *ctx;
        u8 cbc[AES_BLOCK_SIZE];
        u8 *pos = data;
        int i, j, blocks;

        ctx = aes_encrypt_init(key, 16);
        if (ctx == NULL)
                return -1;
        os_memcpy(cbc, iv, AES_BLOCK_SIZE);

        blocks = data_len / AES_BLOCK_SIZE;
        for (i = 0; i < blocks; i++) {
                for (j = 0; j < AES_BLOCK_SIZE; j++)
                        cbc[j] ^= pos[j];
                aes_encrypt(ctx, cbc, cbc);
                os_memcpy(pos, cbc, AES_BLOCK_SIZE);
                pos += AES_BLOCK_SIZE;
        }
        aes_encrypt_deinit(ctx);
        return 0;
}


int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
{
        void *ctx;
        u8 cbc[AES_BLOCK_SIZE], tmp[AES_BLOCK_SIZE];
        u8 *pos = data;
        int i, j, blocks;

        ctx = aes_decrypt_init(key, 16);
        if (ctx == NULL)
                return -1;
        os_memcpy(cbc, iv, AES_BLOCK_SIZE);

        blocks = data_len / AES_BLOCK_SIZE;
        for (i = 0; i < blocks; i++) {
                os_memcpy(tmp, pos, AES_BLOCK_SIZE);
                aes_decrypt(ctx, pos, pos);
                for (j = 0; j < AES_BLOCK_SIZE; j++)
                        pos[j] ^= cbc[j];
                os_memcpy(cbc, tmp, AES_BLOCK_SIZE);
                pos += AES_BLOCK_SIZE;
        }
        aes_decrypt_deinit(ctx);
        return 0;
}