blob: f1a81925558fa196650e3973daa44315caa613b0 [file] [log] [blame]
 /* * 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 #define ARC4_MIN_KEY_SIZE 1 #define ARC4_MAX_KEY_SIZE 256 #define ARC4_BLOCK_SIZE 1 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 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 blkcipher_desc *desc, struct scatterlist *dst, struct scatterlist *src, unsigned int nbytes) { struct arc4_ctx *ctx = crypto_blkcipher_ctx(desc->tfm); struct blkcipher_walk walk; int err; blkcipher_walk_init(&walk, dst, src, nbytes); err = blkcipher_walk_virt(desc, &walk); while (walk.nbytes > 0) { u8 *wsrc = walk.src.virt.addr; u8 *wdst = walk.dst.virt.addr; arc4_crypt(ctx, wdst, wsrc, walk.nbytes); err = blkcipher_walk_done(desc, &walk, 0); } return err; } static struct crypto_alg arc4_algs[2] = { { .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, }, }, }, { .cra_name = "ecb(arc4)", .cra_priority = 100, .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER, .cra_blocksize = ARC4_BLOCK_SIZE, .cra_ctxsize = sizeof(struct arc4_ctx), .cra_alignmask = 0, .cra_type = &crypto_blkcipher_type, .cra_module = THIS_MODULE, .cra_u = { .blkcipher = { .min_keysize = ARC4_MIN_KEY_SIZE, .max_keysize = ARC4_MAX_KEY_SIZE, .setkey = arc4_set_key, .encrypt = ecb_arc4_crypt, .decrypt = ecb_arc4_crypt, }, }, } }; static int __init arc4_init(void) { return crypto_register_algs(arc4_algs, ARRAY_SIZE(arc4_algs)); } static void __exit arc4_exit(void) { crypto_unregister_algs(arc4_algs, ARRAY_SIZE(arc4_algs)); } module_init(arc4_init); module_exit(arc4_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("ARC4 Cipher Algorithm"); MODULE_AUTHOR("Jon Oberheide "); MODULE_ALIAS_CRYPTO("arc4");