1 /* 2 * Cryptographic API 3 * 4 * Michael MIC (IEEE 802.11i/TKIP) keyed digest 5 * 6 * Copyright (c) 2004 Jouni Malinen <jkmaline@cc.hut.fi> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #include <asm/byteorder.h> 14 #include <linux/init.h> 15 #include <linux/module.h> 16 #include <linux/string.h> 17 #include <linux/crypto.h> 18 #include <linux/types.h> 19 20 21 struct michael_mic_ctx { 22 u8 pending[4]; 23 size_t pending_len; 24 25 u32 l, r; 26 }; 27 28 29 static inline u32 xswap(u32 val) 30 { 31 return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8); 32 } 33 34 35 #define michael_block(l, r) \ 36 do { \ 37 r ^= rol32(l, 17); \ 38 l += r; \ 39 r ^= xswap(l); \ 40 l += r; \ 41 r ^= rol32(l, 3); \ 42 l += r; \ 43 r ^= ror32(l, 2); \ 44 l += r; \ 45 } while (0) 46 47 48 static void michael_init(void *ctx) 49 { 50 struct michael_mic_ctx *mctx = ctx; 51 mctx->pending_len = 0; 52 } 53 54 55 static void michael_update(void *ctx, const u8 *data, unsigned int len) 56 { 57 struct michael_mic_ctx *mctx = ctx; 58 const __le32 *src; 59 60 if (mctx->pending_len) { 61 int flen = 4 - mctx->pending_len; 62 if (flen > len) 63 flen = len; 64 memcpy(&mctx->pending[mctx->pending_len], data, flen); 65 mctx->pending_len += flen; 66 data += flen; 67 len -= flen; 68 69 if (mctx->pending_len < 4) 70 return; 71 72 src = (const __le32 *)mctx->pending; 73 mctx->l ^= le32_to_cpup(src); 74 michael_block(mctx->l, mctx->r); 75 mctx->pending_len = 0; 76 } 77 78 src = (const __le32 *)data; 79 80 while (len >= 4) { 81 mctx->l ^= le32_to_cpup(src++); 82 michael_block(mctx->l, mctx->r); 83 len -= 4; 84 } 85 86 if (len > 0) { 87 mctx->pending_len = len; 88 memcpy(mctx->pending, src, len); 89 } 90 } 91 92 93 static void michael_final(void *ctx, u8 *out) 94 { 95 struct michael_mic_ctx *mctx = ctx; 96 u8 *data = mctx->pending; 97 __le32 *dst = (__le32 *)out; 98 99 /* Last block and padding (0x5a, 4..7 x 0) */ 100 switch (mctx->pending_len) { 101 case 0: 102 mctx->l ^= 0x5a; 103 break; 104 case 1: 105 mctx->l ^= data[0] | 0x5a00; 106 break; 107 case 2: 108 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; 109 break; 110 case 3: 111 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | 112 0x5a000000; 113 break; 114 } 115 michael_block(mctx->l, mctx->r); 116 /* l ^= 0; */ 117 michael_block(mctx->l, mctx->r); 118 119 dst[0] = cpu_to_le32(mctx->l); 120 dst[1] = cpu_to_le32(mctx->r); 121 } 122 123 124 static int michael_setkey(void *ctx, const u8 *key, unsigned int keylen, 125 u32 *flags) 126 { 127 struct michael_mic_ctx *mctx = ctx; 128 const __le32 *data = (const __le32 *)key; 129 130 if (keylen != 8) { 131 if (flags) 132 *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; 133 return -EINVAL; 134 } 135 136 mctx->l = le32_to_cpu(data[0]); 137 mctx->r = le32_to_cpu(data[1]); 138 return 0; 139 } 140 141 142 static struct crypto_alg michael_mic_alg = { 143 .cra_name = "michael_mic", 144 .cra_flags = CRYPTO_ALG_TYPE_DIGEST, 145 .cra_blocksize = 8, 146 .cra_ctxsize = sizeof(struct michael_mic_ctx), 147 .cra_module = THIS_MODULE, 148 .cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list), 149 .cra_u = { .digest = { 150 .dia_digestsize = 8, 151 .dia_init = michael_init, 152 .dia_update = michael_update, 153 .dia_final = michael_final, 154 .dia_setkey = michael_setkey } } 155 }; 156 157 158 static int __init michael_mic_init(void) 159 { 160 return crypto_register_alg(&michael_mic_alg); 161 } 162 163 164 static void __exit michael_mic_exit(void) 165 { 166 crypto_unregister_alg(&michael_mic_alg); 167 } 168 169 170 module_init(michael_mic_init); 171 module_exit(michael_mic_exit); 172 173 MODULE_LICENSE("GPL v2"); 174 MODULE_DESCRIPTION("Michael MIC"); 175 MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>"); 176