Commit | Line | Data |
---|---|---|
cfa2b54e | 1 | /* |
1da177e4 LT |
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 | */ | |
ce6dd368 | 14 | |
ce6dd368 | 15 | #include <crypto/algapi.h> |
426bcb50 EB |
16 | #include <crypto/internal/skcipher.h> |
17 | #include <linux/init.h> | |
18 | #include <linux/module.h> | |
1da177e4 LT |
19 | |
20 | #define ARC4_MIN_KEY_SIZE 1 | |
21 | #define ARC4_MAX_KEY_SIZE 256 | |
22 | #define ARC4_BLOCK_SIZE 1 | |
23 | ||
24 | struct arc4_ctx { | |
d366db60 JK |
25 | u32 S[256]; |
26 | u32 x, y; | |
1da177e4 LT |
27 | }; |
28 | ||
6c2bb98b | 29 | static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key, |
560c06ae | 30 | unsigned int key_len) |
1da177e4 | 31 | { |
6c2bb98b | 32 | struct arc4_ctx *ctx = crypto_tfm_ctx(tfm); |
1da177e4 LT |
33 | int i, j = 0, k = 0; |
34 | ||
35 | ctx->x = 1; | |
36 | ctx->y = 0; | |
37 | ||
cfa2b54e | 38 | for (i = 0; i < 256; i++) |
1da177e4 LT |
39 | ctx->S[i] = i; |
40 | ||
cfa2b54e | 41 | for (i = 0; i < 256; i++) { |
d366db60 | 42 | u32 a = ctx->S[i]; |
1da177e4 LT |
43 | j = (j + in_key[k] + a) & 0xff; |
44 | ctx->S[i] = ctx->S[j]; | |
45 | ctx->S[j] = a; | |
cfa2b54e | 46 | if (++k >= key_len) |
1da177e4 LT |
47 | k = 0; |
48 | } | |
49 | ||
50 | return 0; | |
51 | } | |
52 | ||
426bcb50 EB |
53 | static int arc4_set_key_skcipher(struct crypto_skcipher *tfm, const u8 *in_key, |
54 | unsigned int key_len) | |
55 | { | |
56 | return arc4_set_key(&tfm->base, in_key, key_len); | |
57 | } | |
58 | ||
ce6dd368 JK |
59 | static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, |
60 | unsigned int len) | |
1da177e4 | 61 | { |
d366db60 JK |
62 | u32 *const S = ctx->S; |
63 | u32 x, y, a, b; | |
64 | u32 ty, ta, tb; | |
ce6dd368 JK |
65 | |
66 | if (len == 0) | |
67 | return; | |
68 | ||
69 | x = ctx->x; | |
70 | y = ctx->y; | |
1da177e4 LT |
71 | |
72 | a = S[x]; | |
73 | y = (y + a) & 0xff; | |
74 | b = S[y]; | |
ce6dd368 JK |
75 | |
76 | do { | |
77 | S[y] = a; | |
78 | a = (a + b) & 0xff; | |
79 | S[x] = b; | |
80 | x = (x + 1) & 0xff; | |
81 | ta = S[x]; | |
82 | ty = (y + ta) & 0xff; | |
83 | tb = S[ty]; | |
84 | *out++ = *in++ ^ S[a]; | |
85 | if (--len == 0) | |
86 | break; | |
87 | y = ty; | |
88 | a = ta; | |
89 | b = tb; | |
90 | } while (true); | |
1da177e4 LT |
91 | |
92 | ctx->x = x; | |
93 | ctx->y = y; | |
94 | } | |
95 | ||
ce6dd368 JK |
96 | static void arc4_crypt_one(struct crypto_tfm *tfm, u8 *out, const u8 *in) |
97 | { | |
98 | arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1); | |
99 | } | |
100 | ||
426bcb50 | 101 | static int ecb_arc4_crypt(struct skcipher_request *req) |
ce6dd368 | 102 | { |
426bcb50 EB |
103 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
104 | struct arc4_ctx *ctx = crypto_skcipher_ctx(tfm); | |
105 | struct skcipher_walk walk; | |
ce6dd368 JK |
106 | int err; |
107 | ||
426bcb50 | 108 | err = skcipher_walk_virt(&walk, req, false); |
ce6dd368 JK |
109 | |
110 | while (walk.nbytes > 0) { | |
426bcb50 EB |
111 | arc4_crypt(ctx, walk.dst.virt.addr, walk.src.virt.addr, |
112 | walk.nbytes); | |
113 | err = skcipher_walk_done(&walk, 0); | |
ce6dd368 JK |
114 | } |
115 | ||
116 | return err; | |
117 | } | |
118 | ||
426bcb50 | 119 | static struct crypto_alg arc4_cipher = { |
1da177e4 LT |
120 | .cra_name = "arc4", |
121 | .cra_flags = CRYPTO_ALG_TYPE_CIPHER, | |
122 | .cra_blocksize = ARC4_BLOCK_SIZE, | |
123 | .cra_ctxsize = sizeof(struct arc4_ctx), | |
124 | .cra_module = THIS_MODULE, | |
ce6dd368 JK |
125 | .cra_u = { |
126 | .cipher = { | |
127 | .cia_min_keysize = ARC4_MIN_KEY_SIZE, | |
128 | .cia_max_keysize = ARC4_MAX_KEY_SIZE, | |
129 | .cia_setkey = arc4_set_key, | |
130 | .cia_encrypt = arc4_crypt_one, | |
131 | .cia_decrypt = arc4_crypt_one, | |
132 | }, | |
133 | }, | |
426bcb50 EB |
134 | }; |
135 | ||
136 | static struct skcipher_alg arc4_skcipher = { | |
137 | .base.cra_name = "ecb(arc4)", | |
138 | .base.cra_priority = 100, | |
139 | .base.cra_blocksize = ARC4_BLOCK_SIZE, | |
140 | .base.cra_ctxsize = sizeof(struct arc4_ctx), | |
141 | .base.cra_module = THIS_MODULE, | |
142 | .min_keysize = ARC4_MIN_KEY_SIZE, | |
143 | .max_keysize = ARC4_MAX_KEY_SIZE, | |
144 | .setkey = arc4_set_key_skcipher, | |
145 | .encrypt = ecb_arc4_crypt, | |
146 | .decrypt = ecb_arc4_crypt, | |
147 | }; | |
1da177e4 LT |
148 | |
149 | static int __init arc4_init(void) | |
150 | { | |
426bcb50 EB |
151 | int err; |
152 | ||
153 | err = crypto_register_alg(&arc4_cipher); | |
154 | if (err) | |
155 | return err; | |
156 | ||
157 | err = crypto_register_skcipher(&arc4_skcipher); | |
158 | if (err) | |
159 | crypto_unregister_alg(&arc4_cipher); | |
160 | return err; | |
1da177e4 LT |
161 | } |
162 | ||
1da177e4 LT |
163 | static void __exit arc4_exit(void) |
164 | { | |
426bcb50 EB |
165 | crypto_unregister_alg(&arc4_cipher); |
166 | crypto_unregister_skcipher(&arc4_skcipher); | |
1da177e4 LT |
167 | } |
168 | ||
169 | module_init(arc4_init); | |
170 | module_exit(arc4_exit); | |
171 | ||
172 | MODULE_LICENSE("GPL"); | |
173 | MODULE_DESCRIPTION("ARC4 Cipher Algorithm"); | |
174 | MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>"); | |
5d26a105 | 175 | MODULE_ALIAS_CRYPTO("arc4"); |