104 lines
2.0 KiB
C
104 lines
2.0 KiB
C
|
/*
|
||
|
|
* Cryptographic API
|
||
|
|
*
|
||
|
|
* ARC4 Cipher Algorithm
|
||
|
|
*
|
||
|
|
* Jon Oberheide <jon@oberheide.org>
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or modify
|
||
|
|
* it under the terms of the GNU General Public License as published by
|
||
|
|
* the Free Software Foundation; either version 2 of the License, or
|
||
|
|
* (at your option) any later version.
|
||
|
|
*
|
||
|
|
*/
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/init.h>
|
||
|
|
#include <linux/crypto.h>
|
||
|
|
|
||
|
|
#define ARC4_MIN_KEY_SIZE 1
|
||
|
|
#define ARC4_MAX_KEY_SIZE 256
|
||
|
|
#define ARC4_BLOCK_SIZE 1
|
||
|
|
|
||
|
|
struct arc4_ctx {
|
||
|
|
u8 S[256];
|
||
|
|
u8 x, y;
|
||
|
|
};
|
||
|
|
|
||
|
|
static int arc4_set_key(void *ctx_arg, const u8 *in_key, unsigned int key_len, u32 *flags)
|
||
|
|
{
|
||
|
|
struct arc4_ctx *ctx = ctx_arg;
|
||
|
|
int i, j = 0, k = 0;
|
||
|
|
|
||
|
|
ctx->x = 1;
|
||
|
|
ctx->y = 0;
|
||
|
|
|
||
|
|
for(i = 0; i < 256; i++)
|
||
|
|
ctx->S[i] = i;
|
||
|
|
|
||
|
|
for(i = 0; i < 256; i++)
|
||
|
|
{
|
||
|
|
u8 a = ctx->S[i];
|
||
|
|
j = (j + in_key[k] + a) & 0xff;
|
||
|
|
ctx->S[i] = ctx->S[j];
|
||
|
|
ctx->S[j] = a;
|
||
|
|
if(++k >= key_len)
|
||
|
|
k = 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void arc4_crypt(void *ctx_arg, u8 *out, const u8 *in)
|
||
|
|
{
|
||
|
|
struct arc4_ctx *ctx = ctx_arg;
|
||
|
|
|
||
|
|
u8 *const S = ctx->S;
|
||
|
|
u8 x = ctx->x;
|
||
|
|
u8 y = ctx->y;
|
||
|
|
u8 a, b;
|
||
|
|
|
||
|
|
a = S[x];
|
||
|
|
y = (y + a) & 0xff;
|
||
|
|
b = S[y];
|
||
|
|
S[x] = b;
|
||
|
|
S[y] = a;
|
||
|
|
x = (x + 1) & 0xff;
|
||
|
|
*out++ = *in ^ S[(a + b) & 0xff];
|
||
|
|
|
||
|
|
ctx->x = x;
|
||
|
|
ctx->y = y;
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct crypto_alg arc4_alg = {
|
||
|
|
.cra_name = "arc4",
|
||
|
|
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
|
||
|
|
.cra_blocksize = ARC4_BLOCK_SIZE,
|
||
|
|
.cra_ctxsize = sizeof(struct arc4_ctx),
|
||
|
|
.cra_module = THIS_MODULE,
|
||
|
|
.cra_list = LIST_HEAD_INIT(arc4_alg.cra_list),
|
||
|
|
.cra_u = { .cipher = {
|
||
|
|
.cia_min_keysize = ARC4_MIN_KEY_SIZE,
|
||
|
|
.cia_max_keysize = ARC4_MAX_KEY_SIZE,
|
||
|
|
.cia_setkey = arc4_set_key,
|
||
|
|
.cia_encrypt = arc4_crypt,
|
||
|
|
.cia_decrypt = arc4_crypt } }
|
||
|
|
};
|
||
|
|
|
||
|
|
static int __init arc4_init(void)
|
||
|
|
{
|
||
|
|
return crypto_register_alg(&arc4_alg);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static void __exit arc4_exit(void)
|
||
|
|
{
|
||
|
|
crypto_unregister_alg(&arc4_alg);
|
||
|
|
}
|
||
|
|
|
||
|
|
module_init(arc4_init);
|
||
|
|
module_exit(arc4_exit);
|
||
|
|
|
||
|
|
MODULE_LICENSE("GPL");
|
||
|
|
MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
|
||
|
|
MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
|