4 * ARC4 Cipher Algorithm
6 * Jon Oberheide <jon@oberheide.org>
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.
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/crypto.h>
18 #include <crypto/algapi.h>
20 #define ARC4_MIN_KEY_SIZE 1
21 #define ARC4_MAX_KEY_SIZE 256
22 #define ARC4_BLOCK_SIZE 1
29 static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
32 struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
38 for (i = 0; i < 256; i++)
41 for (i = 0; i < 256; i++) {
43 j = (j + in_key[k] + a) & 0xff;
44 ctx->S[i] = ctx->S[j];
53 static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in,
56 u32 *const S = ctx->S;
78 *out++ = *in++ ^ S[a];
90 static void arc4_crypt_one(struct crypto_tfm *tfm, u8 *out, const u8 *in)
92 arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1);
95 static int ecb_arc4_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
96 struct scatterlist *src, unsigned int nbytes)
98 struct arc4_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
99 struct blkcipher_walk walk;
102 blkcipher_walk_init(&walk, dst, src, nbytes);
104 err = blkcipher_walk_virt(desc, &walk);
106 while (walk.nbytes > 0) {
107 u8 *wsrc = walk.src.virt.addr;
108 u8 *wdst = walk.dst.virt.addr;
110 arc4_crypt(ctx, wdst, wsrc, walk.nbytes);
112 err = blkcipher_walk_done(desc, &walk, 0);
118 static struct crypto_alg arc4_algs[2] = { {
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,
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,
134 .cra_name = "ecb(arc4)",
136 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
137 .cra_blocksize = ARC4_BLOCK_SIZE,
138 .cra_ctxsize = sizeof(struct arc4_ctx),
140 .cra_type = &crypto_blkcipher_type,
141 .cra_module = THIS_MODULE,
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,
153 static int __init arc4_init(void)
155 return crypto_register_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
158 static void __exit arc4_exit(void)
160 crypto_unregister_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
163 module_init(arc4_init);
164 module_exit(arc4_exit);
166 MODULE_LICENSE("GPL");
167 MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
168 MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
169 MODULE_ALIAS_CRYPTO("arc4");