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 /* * 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 #define ARC4_MIN_KEY_SIZE 1 #define ARC4_MAX_KEY_SIZE 256 #define ARC4_BLOCK_SIZE 1 struct arc4_ctx { u8 S[256]; u8 x, y; }; static int arc4_set_key(void *ctx_arg, const u8 *in_key, unsigned int key_len, u32 *flags) { struct arc4_ctx *ctx = ctx_arg; 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++) { u8 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(void *ctx_arg, u8 *out, const u8 *in) { struct arc4_ctx *ctx = ctx_arg; u8 *const S = ctx->S; u8 x = ctx->x; u8 y = ctx->y; u8 a, b; a = S[x]; y = (y + a) & 0xff; b = S[y]; S[x] = b; S[y] = a; x = (x + 1) & 0xff; *out++ = *in ^ S[(a + b) & 0xff]; ctx->x = x; ctx->y = y; } static struct crypto_alg arc4_alg = { .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_list = LIST_HEAD_INIT(arc4_alg.cra_list), .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, .cia_decrypt = arc4_crypt } } }; static int __init arc4_init(void) { return crypto_register_alg(&arc4_alg); } static void __exit arc4_exit(void) { crypto_unregister_alg(&arc4_alg); } module_init(arc4_init); module_exit(arc4_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("ARC4 Cipher Algorithm"); MODULE_AUTHOR("Jon Oberheide ");