diff options
Diffstat (limited to 'crypto/michael_mic.c')
| -rw-r--r-- | crypto/michael_mic.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/crypto/michael_mic.c b/crypto/michael_mic.c new file mode 100644 index 0000000..a470bcb --- /dev/null +++ b/crypto/michael_mic.c @@ -0,0 +1,181 @@ +/* + * 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>"); |