/* * Cryptographic API * * Michael MIC (IEEE 802.11i/TKIP) keyed digest * * Copyright (c) 2004 Jouni Malinen <j@w1.fi> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <asm/byteorder.h> #include <linux/init.h> #include <linux/module.h> #include <linux/string.h> #include <linux/crypto.h> #include <linux/types.h> struct michael_mic_ctx { u8 pending[4]; size_t pending_len; u32 l, r; }; static inline u32 xswap(u32 val) { return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8); } #define michael_block(l, r) \ do { \ r ^= rol32(l, 17); \ l += r; \ r ^= xswap(l); \ l += r; \ r ^= rol32(l, 3); \ l += r; \ r ^= ror32(l, 2); \ l += r; \ } while (0) static void michael_init(struct crypto_tfm *tfm) { struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); mctx->pending_len = 0; } static void michael_update(struct crypto_tfm *tfm, const u8 *data, unsigned int len) { struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); const __le32 *src; if (mctx->pending_len) { int flen = 4 - mctx->pending_len; if (flen > len) flen = len; memcpy(&mctx->pending[mctx->pending_len], data, flen); mctx->pending_len += flen; data += flen; len -= flen; if (mctx->pending_len < 4) return; src = (const __le32 *)mctx->pending; mctx->l ^= le32_to_cpup(src); michael_block(mctx->l, mctx->r); mctx->pending_len = 0; } src = (const __le32 *)data; while (len >= 4) { mctx->l ^= le32_to_cpup(src++); michael_block(mctx->l, mctx->r); len -= 4; } if (len > 0) { mctx->pending_len = len; memcpy(mctx->pending, src, len); } } static void michael_final(struct crypto_tfm *tfm, u8 *out) { struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); u8 *data = mctx->pending; __le32 *dst = (__le32 *)out; /* Last block and padding (0x5a, 4..7 x 0) */ switch (mctx->pending_len) { case 0: mctx->l ^= 0x5a; break; case 1: mctx->l ^= data[0] | 0x5a00; break; case 2: mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; break; case 3: mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | 0x5a000000; break; } michael_block(mctx->l, mctx->r); /* l ^= 0; */ michael_block(mctx->l, mctx->r); dst[0] = cpu_to_le32(mctx->l); dst[1] = cpu_to_le32(mctx->r); } static int michael_setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen) { struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); const __le32 *data = (const __le32 *)key; if (keylen != 8) { tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; return -EINVAL; } mctx->l = le32_to_cpu(data[0]); mctx->r = le32_to_cpu(data[1]); return 0; } static struct crypto_alg michael_mic_alg = { .cra_name = "michael_mic", .cra_flags = CRYPTO_ALG_TYPE_DIGEST, .cra_blocksize = 8, .cra_ctxsize = sizeof(struct michael_mic_ctx), .cra_module = THIS_MODULE, .cra_alignmask = 3, .cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list), .cra_u = { .digest = { .dia_digestsize = 8, .dia_init = michael_init, .dia_update = michael_update, .dia_final = michael_final, .dia_setkey = michael_setkey } } }; static int __init michael_mic_init(void) { return crypto_register_alg(&michael_mic_alg); } static void __exit michael_mic_exit(void) { crypto_unregister_alg(&michael_mic_alg); } module_init(michael_mic_init); module_exit(michael_mic_exit); MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("Michael MIC"); MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");