Mati Vait | cfa2b54 | 2011-06-08 21:26:00 +0800 | [diff] [blame] | 1 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | */ |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 14 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | #include <linux/module.h> |
| 16 | #include <linux/init.h> |
| 17 | #include <linux/crypto.h> |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 18 | #include <crypto/algapi.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 { |
Jussi Kivilinna | d366db6 | 2012-06-09 18:25:46 +0300 | [diff] [blame] | 25 | u32 S[256]; |
| 26 | u32 x, y; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | }; |
| 28 | |
Herbert Xu | 6c2bb98 | 2006-05-16 22:09:29 +1000 | [diff] [blame] | 29 | static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key, |
Herbert Xu | 560c06a | 2006-08-13 14:16:39 +1000 | [diff] [blame] | 30 | unsigned int key_len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | { |
Herbert Xu | 6c2bb98 | 2006-05-16 22:09:29 +1000 | [diff] [blame] | 32 | struct arc4_ctx *ctx = crypto_tfm_ctx(tfm); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 33 | int i, j = 0, k = 0; |
| 34 | |
| 35 | ctx->x = 1; |
| 36 | ctx->y = 0; |
| 37 | |
Mati Vait | cfa2b54 | 2011-06-08 21:26:00 +0800 | [diff] [blame] | 38 | for (i = 0; i < 256; i++) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | ctx->S[i] = i; |
| 40 | |
Mati Vait | cfa2b54 | 2011-06-08 21:26:00 +0800 | [diff] [blame] | 41 | for (i = 0; i < 256; i++) { |
Jussi Kivilinna | d366db6 | 2012-06-09 18:25:46 +0300 | [diff] [blame] | 42 | u32 a = ctx->S[i]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | j = (j + in_key[k] + a) & 0xff; |
| 44 | ctx->S[i] = ctx->S[j]; |
| 45 | ctx->S[j] = a; |
Mati Vait | cfa2b54 | 2011-06-08 21:26:00 +0800 | [diff] [blame] | 46 | if (++k >= key_len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | k = 0; |
| 48 | } |
| 49 | |
| 50 | return 0; |
| 51 | } |
| 52 | |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 53 | static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, |
| 54 | unsigned int len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 55 | { |
Jussi Kivilinna | d366db6 | 2012-06-09 18:25:46 +0300 | [diff] [blame] | 56 | u32 *const S = ctx->S; |
| 57 | u32 x, y, a, b; |
| 58 | u32 ty, ta, tb; |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 59 | |
| 60 | if (len == 0) |
| 61 | return; |
| 62 | |
| 63 | x = ctx->x; |
| 64 | y = ctx->y; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 65 | |
| 66 | a = S[x]; |
| 67 | y = (y + a) & 0xff; |
| 68 | b = S[y]; |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 69 | |
| 70 | do { |
| 71 | S[y] = a; |
| 72 | a = (a + b) & 0xff; |
| 73 | S[x] = b; |
| 74 | x = (x + 1) & 0xff; |
| 75 | ta = S[x]; |
| 76 | ty = (y + ta) & 0xff; |
| 77 | tb = S[ty]; |
| 78 | *out++ = *in++ ^ S[a]; |
| 79 | if (--len == 0) |
| 80 | break; |
| 81 | y = ty; |
| 82 | a = ta; |
| 83 | b = tb; |
| 84 | } while (true); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | |
| 86 | ctx->x = x; |
| 87 | ctx->y = y; |
| 88 | } |
| 89 | |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 90 | static void arc4_crypt_one(struct crypto_tfm *tfm, u8 *out, const u8 *in) |
| 91 | { |
| 92 | arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1); |
| 93 | } |
| 94 | |
| 95 | static int ecb_arc4_crypt(struct blkcipher_desc *desc, struct scatterlist *dst, |
| 96 | struct scatterlist *src, unsigned int nbytes) |
| 97 | { |
| 98 | struct arc4_ctx *ctx = crypto_blkcipher_ctx(desc->tfm); |
| 99 | struct blkcipher_walk walk; |
| 100 | int err; |
| 101 | |
| 102 | blkcipher_walk_init(&walk, dst, src, nbytes); |
| 103 | |
| 104 | err = blkcipher_walk_virt(desc, &walk); |
| 105 | |
| 106 | while (walk.nbytes > 0) { |
| 107 | u8 *wsrc = walk.src.virt.addr; |
| 108 | u8 *wdst = walk.dst.virt.addr; |
| 109 | |
| 110 | arc4_crypt(ctx, wdst, wsrc, walk.nbytes); |
| 111 | |
| 112 | err = blkcipher_walk_done(desc, &walk, 0); |
| 113 | } |
| 114 | |
| 115 | return err; |
| 116 | } |
| 117 | |
| 118 | static struct crypto_alg arc4_algs[2] = { { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 119 | .cra_name = "arc4", |
| 120 | .cra_flags = CRYPTO_ALG_TYPE_CIPHER, |
| 121 | .cra_blocksize = ARC4_BLOCK_SIZE, |
| 122 | .cra_ctxsize = sizeof(struct arc4_ctx), |
| 123 | .cra_module = THIS_MODULE, |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 124 | .cra_u = { |
| 125 | .cipher = { |
| 126 | .cia_min_keysize = ARC4_MIN_KEY_SIZE, |
| 127 | .cia_max_keysize = ARC4_MAX_KEY_SIZE, |
| 128 | .cia_setkey = arc4_set_key, |
| 129 | .cia_encrypt = arc4_crypt_one, |
| 130 | .cia_decrypt = arc4_crypt_one, |
| 131 | }, |
| 132 | }, |
| 133 | }, { |
| 134 | .cra_name = "ecb(arc4)", |
| 135 | .cra_priority = 100, |
| 136 | .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER, |
| 137 | .cra_blocksize = ARC4_BLOCK_SIZE, |
| 138 | .cra_ctxsize = sizeof(struct arc4_ctx), |
| 139 | .cra_alignmask = 0, |
| 140 | .cra_type = &crypto_blkcipher_type, |
| 141 | .cra_module = THIS_MODULE, |
| 142 | .cra_u = { |
| 143 | .blkcipher = { |
| 144 | .min_keysize = ARC4_MIN_KEY_SIZE, |
| 145 | .max_keysize = ARC4_MAX_KEY_SIZE, |
| 146 | .setkey = arc4_set_key, |
| 147 | .encrypt = ecb_arc4_crypt, |
| 148 | .decrypt = ecb_arc4_crypt, |
| 149 | }, |
| 150 | }, |
| 151 | } }; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 152 | |
| 153 | static int __init arc4_init(void) |
| 154 | { |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 155 | return crypto_register_algs(arc4_algs, ARRAY_SIZE(arc4_algs)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 156 | } |
| 157 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 158 | static void __exit arc4_exit(void) |
| 159 | { |
Jussi Kivilinna | ce6dd36 | 2012-06-09 18:25:40 +0300 | [diff] [blame] | 160 | crypto_unregister_algs(arc4_algs, ARRAY_SIZE(arc4_algs)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 161 | } |
| 162 | |
| 163 | module_init(arc4_init); |
| 164 | module_exit(arc4_exit); |
| 165 | |
| 166 | MODULE_LICENSE("GPL"); |
| 167 | MODULE_DESCRIPTION("ARC4 Cipher Algorithm"); |
| 168 | MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>"); |
Kees Cook | 5d26a10 | 2014-11-20 17:05:53 -0800 | [diff] [blame^] | 169 | MODULE_ALIAS_CRYPTO("arc4"); |