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path: root/crypto/arc4.c
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 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 ``` ``````/* * Cryptographic API * * ARC4 Cipher Algorithm * * Jon Oberheide * * 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 #include #include #include #include struct arc4_ctx { u32 S[256]; u32 x, y; }; static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key, unsigned int key_len) { 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++) { u32 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 int arc4_set_key_skcipher(struct crypto_skcipher *tfm, const u8 *in_key, unsigned int key_len) { return arc4_set_key(&tfm->base, in_key, key_len); } static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len) { u32 *const S = ctx->S; u32 x, y, a, b; u32 ty, ta, tb; if (len == 0) return; x = ctx->x; y = ctx->y; a = S[x]; y = (y + a) & 0xff; b = S[y]; do { S[y] = a; a = (a + b) & 0xff; S[x] = b; x = (x + 1) & 0xff; ta = S[x]; ty = (y + ta) & 0xff; tb = S[ty]; *out++ = *in++ ^ S[a]; if (--len == 0) break; y = ty; a = ta; b = tb; } while (true); ctx->x = x; ctx->y = y; } static void arc4_crypt_one(struct crypto_tfm *tfm, u8 *out, const u8 *in) { arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1); } static int ecb_arc4_crypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct arc4_ctx *ctx = crypto_skcipher_ctx(tfm); struct skcipher_walk walk; int err; err = skcipher_walk_virt(&walk, req, false); while (walk.nbytes > 0) { arc4_crypt(ctx, walk.dst.virt.addr, walk.src.virt.addr, walk.nbytes); err = skcipher_walk_done(&walk, 0); } return err; } static struct crypto_alg arc4_cipher = { .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_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_one, .cia_decrypt = arc4_crypt_one, }, }, }; static struct skcipher_alg arc4_skcipher = { .base.cra_name = "ecb(arc4)", .base.cra_priority = 100, .base.cra_blocksize = ARC4_BLOCK_SIZE, .base.cra_ctxsize = sizeof(struct arc4_ctx), .base.cra_module = THIS_MODULE, .min_keysize = ARC4_MIN_KEY_SIZE, .max_keysize = ARC4_MAX_KEY_SIZE, .setkey = arc4_set_key_skcipher, .encrypt = ecb_arc4_crypt, .decrypt = ecb_arc4_crypt, }; static int __init arc4_init(void) { int err; err = crypto_register_alg(&arc4_cipher); if (err) return err; err = crypto_register_skcipher(&arc4_skcipher); if (err) crypto_unregister_alg(&arc4_cipher); return err; } static void __exit arc4_exit(void) { crypto_unregister_alg(&arc4_cipher); crypto_unregister_skcipher(&arc4_skcipher); } module_init(arc4_init); module_exit(arc4_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("ARC4 Cipher Algorithm"); MODULE_AUTHOR("Jon Oberheide "); MODULE_ALIAS_CRYPTO("arc4"); ``````