/* * Cryptographic API * * Michael MIC (IEEE 802.11i/TKIP) keyed digest * * Copyright (c) 2004 Jouni Malinen <jkmaline@cc.hut.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 <linux/init.h> #include <linux/module.h> #include <linux/string.h> #include <linux/crypto.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 inline u32 get_le32(const u8 *p) { return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24); } static inline void put_le32(u8 *p, u32 v) { p[0] = v; p[1] = v >> 8; p[2] = v >> 16; p[3] = v >> 24; } static void michael_init(void *ctx) { struct michael_mic_ctx *mctx = ctx; mctx->pending_len = 0; } static void michael_update(void *ctx, const u8 *data, unsigned int len) { struct michael_mic_ctx *mctx = ctx; 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; mctx->l ^= get_le32(mctx->pending); michael_block(mctx->l, mctx->r); mctx->pending_len = 0; } while (len >= 4) { mctx->l ^= get_le32(data); michael_block(mctx->l, mctx->r); data += 4; len -= 4; } if (len > 0) { mctx->pending_len = len; memcpy(mctx->pending, data, len); } } static void michael_final(void *ctx, u8 *out) { struct michael_mic_ctx *mctx = ctx; u8 *data = mctx->pending; /* 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); put_le32(out, mctx->l); put_le32(out + 4, mctx->r); } static int michael_setkey(void *ctx, const u8 *key, unsigned int keylen, u32 *flags) { struct michael_mic_ctx *mctx = ctx; if (keylen != 8) { if (flags) *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; return -EINVAL; } mctx->l = get_le32(key); mctx->r = get_le32(key + 4); 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_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 <jkmaline@cc.hut.fi>");