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1/*
2 * Cryptographic API
3 *
4 * ARC4 Cipher Algorithm
5 *
6 * Jon Oberheide <jon@oberheide.org>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 */
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/crypto.h>
17
18#define ARC4_MIN_KEY_SIZE 1
19#define ARC4_MAX_KEY_SIZE 256
20#define ARC4_BLOCK_SIZE 1
21
22struct arc4_ctx {
23 u8 S[256];
24 u8 x, y;
25};
26
27static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
28 unsigned int key_len)
29{
30 struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
31 int i, j = 0, k = 0;
32
33 ctx->x = 1;
34 ctx->y = 0;
35
36 for (i = 0; i < 256; i++)
37 ctx->S[i] = i;
38
39 for (i = 0; i < 256; i++) {
40 u8 a = ctx->S[i];
41 j = (j + in_key[k] + a) & 0xff;
42 ctx->S[i] = ctx->S[j];
43 ctx->S[j] = a;
44 if (++k >= key_len)
45 k = 0;
46 }
47
48 return 0;
49}
50
51static void arc4_crypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
52{
53 struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
54
55 u8 *const S = ctx->S;
56 u8 x = ctx->x;
57 u8 y = ctx->y;
58 u8 a, b;
59
60 a = S[x];
61 y = (y + a) & 0xff;
62 b = S[y];
63 S[x] = b;
64 S[y] = a;
65 x = (x + 1) & 0xff;
66 *out++ = *in ^ S[(a + b) & 0xff];
67
68 ctx->x = x;
69 ctx->y = y;
70}
71
72static struct crypto_alg arc4_alg = {
73 .cra_name = "arc4",
74 .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
75 .cra_blocksize = ARC4_BLOCK_SIZE,
76 .cra_ctxsize = sizeof(struct arc4_ctx),
77 .cra_module = THIS_MODULE,
78 .cra_list = LIST_HEAD_INIT(arc4_alg.cra_list),
79 .cra_u = { .cipher = {
80 .cia_min_keysize = ARC4_MIN_KEY_SIZE,
81 .cia_max_keysize = ARC4_MAX_KEY_SIZE,
82 .cia_setkey = arc4_set_key,
83 .cia_encrypt = arc4_crypt,
84 .cia_decrypt = arc4_crypt } }
85};
86
87static int __init arc4_init(void)
88{
89 return crypto_register_alg(&arc4_alg);
90}
91
92
93static void __exit arc4_exit(void)
94{
95 crypto_unregister_alg(&arc4_alg);
96}
97
98module_init(arc4_init);
99module_exit(arc4_exit);
100
101MODULE_LICENSE("GPL");
102MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
103MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
1/*
2 * Cryptographic API
3 *
4 * ARC4 Cipher Algorithm
5 *
6 * Jon Oberheide <jon@oberheide.org>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 */
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/crypto.h>
17
18#define ARC4_MIN_KEY_SIZE 1
19#define ARC4_MAX_KEY_SIZE 256
20#define ARC4_BLOCK_SIZE 1
21
22struct arc4_ctx {
23 u8 S[256];
24 u8 x, y;
25};
26
27static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
28 unsigned int key_len)
29{
30 struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
31 int i, j = 0, k = 0;
32
33 ctx->x = 1;
34 ctx->y = 0;
35
36 for (i = 0; i < 256; i++)
37 ctx->S[i] = i;
38
39 for (i = 0; i < 256; i++) {
40 u8 a = ctx->S[i];
41 j = (j + in_key[k] + a) & 0xff;
42 ctx->S[i] = ctx->S[j];
43 ctx->S[j] = a;
44 if (++k >= key_len)
45 k = 0;
46 }
47
48 return 0;
49}
50
51static void arc4_crypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
52{
53 struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
54
55 u8 *const S = ctx->S;
56 u8 x = ctx->x;
57 u8 y = ctx->y;
58 u8 a, b;
59
60 a = S[x];
61 y = (y + a) & 0xff;
62 b = S[y];
63 S[x] = b;
64 S[y] = a;
65 x = (x + 1) & 0xff;
66 *out++ = *in ^ S[(a + b) & 0xff];
67
68 ctx->x = x;
69 ctx->y = y;
70}
71
72static struct crypto_alg arc4_alg = {
73 .cra_name = "arc4",
74 .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
75 .cra_blocksize = ARC4_BLOCK_SIZE,
76 .cra_ctxsize = sizeof(struct arc4_ctx),
77 .cra_module = THIS_MODULE,
78 .cra_list = LIST_HEAD_INIT(arc4_alg.cra_list),
79 .cra_u = { .cipher = {
80 .cia_min_keysize = ARC4_MIN_KEY_SIZE,
81 .cia_max_keysize = ARC4_MAX_KEY_SIZE,
82 .cia_setkey = arc4_set_key,
83 .cia_encrypt = arc4_crypt,
84 .cia_decrypt = arc4_crypt } }
85};
86
87static int __init arc4_init(void)
88{
89 return crypto_register_alg(&arc4_alg);
90}
91
92
93static void __exit arc4_exit(void)
94{
95 crypto_unregister_alg(&arc4_alg);
96}
97
98module_init(arc4_init);
99module_exit(arc4_exit);
100
101MODULE_LICENSE("GPL");
102MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
103MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");