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crypto/michael_mic.c
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/* * Cryptographic API * * Michael MIC (IEEE 802.11i/TKIP) keyed digest * |
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* Copyright (c) 2004 Jouni Malinen <j@w1.fi> |
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* * 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. */ |
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#include <crypto/internal/hash.h> |
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#include <asm/byteorder.h> |
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#include <linux/init.h> #include <linux/module.h> #include <linux/string.h> |
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#include <linux/types.h> |
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struct michael_mic_ctx { |
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u32 l, r; }; struct michael_mic_desc_ctx { |
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u8 pending[4]; size_t pending_len; u32 l, r; }; |
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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) |
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static int michael_init(struct shash_desc *desc) |
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{ |
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struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm); |
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mctx->pending_len = 0; |
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mctx->l = ctx->l; mctx->r = ctx->r; return 0; |
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} |
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static int michael_update(struct shash_desc *desc, const u8 *data, |
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unsigned int len) |
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{ |
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struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); |
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const __le32 *src; |
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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) |
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return 0; |
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src = (const __le32 *)mctx->pending; mctx->l ^= le32_to_cpup(src); |
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michael_block(mctx->l, mctx->r); mctx->pending_len = 0; } |
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src = (const __le32 *)data; |
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while (len >= 4) { |
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mctx->l ^= le32_to_cpup(src++); |
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michael_block(mctx->l, mctx->r); |
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len -= 4; } if (len > 0) { mctx->pending_len = len; |
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memcpy(mctx->pending, src, len); |
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} |
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return 0; |
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} |
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static int michael_final(struct shash_desc *desc, u8 *out) |
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{ |
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struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); |
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u8 *data = mctx->pending; |
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__le32 *dst = (__le32 *)out; |
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/* 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); |
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dst[0] = cpu_to_le32(mctx->l); dst[1] = cpu_to_le32(mctx->r); |
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return 0; |
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} |
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static int michael_setkey(struct crypto_shash *tfm, const u8 *key, |
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unsigned int keylen) |
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{ |
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struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm); |
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const __le32 *data = (const __le32 *)key; |
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if (keylen != 8) { |
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crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); |
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return -EINVAL; } |
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mctx->l = le32_to_cpu(data[0]); mctx->r = le32_to_cpu(data[1]); |
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return 0; } |
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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, } |
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}; |
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static int __init michael_mic_init(void) { |
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return crypto_register_shash(&alg); |
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} static void __exit michael_mic_exit(void) { |
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crypto_unregister_shash(&alg); |
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} module_init(michael_mic_init); module_exit(michael_mic_exit); MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("Michael MIC"); |
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MODULE_AUTHOR("Jouni Malinen <j@w1.fi>"); |
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MODULE_ALIAS_CRYPTO("michael_mic"); |