diff options
Diffstat (limited to 'crypto/michael_mic.c')
| -rw-r--r-- | crypto/michael_mic.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/crypto/michael_mic.c b/crypto/michael_mic.c new file mode 100644 index 00000000..079b761b --- /dev/null +++ b/crypto/michael_mic.c @@ -0,0 +1,186 @@ +/* + * 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 <crypto/internal/hash.h> +#include <asm/byteorder.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/string.h> +#include <linux/types.h> + + +struct michael_mic_ctx { + u32 l, r; +}; + +struct michael_mic_desc_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 int michael_init(struct shash_desc *desc) +{ + struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); + struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm); + mctx->pending_len = 0; + mctx->l = ctx->l; + mctx->r = ctx->r; + + return 0; +} + + +static int michael_update(struct shash_desc *desc, const u8 *data, + unsigned int len) +{ + struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); + 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 0; + + 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); + } + + return 0; +} + + +static int michael_final(struct shash_desc *desc, u8 *out) +{ + struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); + 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); + + return 0; +} + + +static int michael_setkey(struct crypto_shash *tfm, const u8 *key, + unsigned int keylen) +{ + struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm); + + const __le32 *data = (const __le32 *)key; + + if (keylen != 8) { + crypto_shash_set_flags(tfm, 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 shash_alg alg = { + .digestsize = 8, + .setkey = michael_setkey, + .init = michael_init, + .update = michael_update, + .final = michael_final, + .descsize = sizeof(struct michael_mic_desc_ctx), + .base = { + .cra_name = "michael_mic", + .cra_blocksize = 8, + .cra_alignmask = 3, + .cra_ctxsize = sizeof(struct michael_mic_ctx), + .cra_module = THIS_MODULE, + } +}; + +static int __init michael_mic_init(void) +{ + return crypto_register_shash(&alg); +} + + +static void __exit michael_mic_exit(void) +{ + crypto_unregister_shash(&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>"); |