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(struct crypto_tfm *tfm) 49 { 50 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); 51 mctx->pending_len = 0; 52 } 53 54 55 static void michael_update(struct crypto_tfm *tfm, const u8 *data, 56 unsigned int len) 57 { 58 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); 59 const __le32 *src; 60 61 if (mctx->pending_len) { 62 int flen = 4 - mctx->pending_len; 63 if (flen > len) 64 flen = len; 65 memcpy(&mctx->pending[mctx->pending_len], data, flen); 66 mctx->pending_len += flen; 67 data += flen; 68 len -= flen; 69 70 if (mctx->pending_len < 4) 71 return; 72 73 src = (const __le32 *)mctx->pending; 74 mctx->l ^= le32_to_cpup(src); 75 michael_block(mctx->l, mctx->r); 76 mctx->pending_len = 0; 77 } 78 79 src = (const __le32 *)data; 80 81 while (len >= 4) { 82 mctx->l ^= le32_to_cpup(src++); 83 michael_block(mctx->l, mctx->r); 84 len -= 4; 85 } 86 87 if (len > 0) { 88 mctx->pending_len = len; 89 memcpy(mctx->pending, src, len); 90 } 91 } 92 93 94 static void michael_final(struct crypto_tfm *tfm, u8 *out) 95 { 96 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); 97 u8 *data = mctx->pending; 98 __le32 *dst = (__le32 *)out; 99 100 /* Last block and padding (0x5a, 4..7 x 0) */ 101 switch (mctx->pending_len) { 102 case 0: 103 mctx->l ^= 0x5a; 104 break; 105 case 1: 106 mctx->l ^= data[0] | 0x5a00; 107 break; 108 case 2: 109 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; 110 break; 111 case 3: 112 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | 113 0x5a000000; 114 break; 115 } 116 michael_block(mctx->l, mctx->r); 117 /* l ^= 0; */ 118 michael_block(mctx->l, mctx->r); 119 120 dst[0] = cpu_to_le32(mctx->l); 121 dst[1] = cpu_to_le32(mctx->r); 122 } 123 124 125 static int michael_setkey(struct crypto_tfm *tfm, const u8 *key, 126 unsigned int keylen) 127 { 128 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm); 129 const __le32 *data = (const __le32 *)key; 130 131 if (keylen != 8) { 132 tfm->crt_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_alignmask = 3, 149 .cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list), 150 .cra_u = { .digest = { 151 .dia_digestsize = 8, 152 .dia_init = michael_init, 153 .dia_update = michael_update, 154 .dia_final = michael_final, 155 .dia_setkey = michael_setkey } } 156 }; 157 158 159 static int __init michael_mic_init(void) 160 { 161 return crypto_register_alg(&michael_mic_alg); 162 } 163 164 165 static void __exit michael_mic_exit(void) 166 { 167 crypto_unregister_alg(&michael_mic_alg); 168 } 169 170 171 module_init(michael_mic_init); 172 module_exit(michael_mic_exit); 173 174 MODULE_LICENSE("GPL v2"); 175 MODULE_DESCRIPTION("Michael MIC"); 176 MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>"); 177