linux/crypto/arc4.c
Herbert Xu 6c2bb98bc3 [CRYPTO] all: Pass tfm instead of ctx to algorithms
Up until now algorithms have been happy to get a context pointer since
they know everything that's in the tfm already (e.g., alignment, block
size).

However, once we have parameterised algorithms, such information will
be specific to each tfm.  So the algorithm API needs to be changed to
pass the tfm structure instead of the context pointer.

This patch is basically a text substitution.  The only tricky bit is
the assembly routines that need to get the context pointer offset
through asm-offsets.h.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2006-06-26 17:34:39 +10:00

104 lines
2.1 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(struct crypto_tfm *tfm, const u8 *in_key,
unsigned int key_len, u32 *flags)
{
struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
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(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
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>");