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 <linux/init.h> 14 #include <linux/module.h> 15 #include <linux/string.h> 16 #include <linux/crypto.h> 17 18 19 struct michael_mic_ctx { 20 u8 pending[4]; 21 size_t pending_len; 22 23 u32 l, r; 24 }; 25 26 27 static inline u32 xswap(u32 val) 28 { 29 return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8); 30 } 31 32 33 #define michael_block(l, r) \ 34 do { \ 35 r ^= rol32(l, 17); \ 36 l += r; \ 37 r ^= xswap(l); \ 38 l += r; \ 39 r ^= rol32(l, 3); \ 40 l += r; \ 41 r ^= ror32(l, 2); \ 42 l += r; \ 43 } while (0) 44 45 46 static inline u32 get_le32(const u8 *p) 47 { 48 return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24); 49 } 50 51 52 static inline void put_le32(u8 *p, u32 v) 53 { 54 p[0] = v; 55 p[1] = v >> 8; 56 p[2] = v >> 16; 57 p[3] = v >> 24; 58 } 59 60 61 static void michael_init(void *ctx) 62 { 63 struct michael_mic_ctx *mctx = ctx; 64 mctx->pending_len = 0; 65 } 66 67 68 static void michael_update(void *ctx, const u8 *data, unsigned int len) 69 { 70 struct michael_mic_ctx *mctx = ctx; 71 72 if (mctx->pending_len) { 73 int flen = 4 - mctx->pending_len; 74 if (flen > len) 75 flen = len; 76 memcpy(&mctx->pending[mctx->pending_len], data, flen); 77 mctx->pending_len += flen; 78 data += flen; 79 len -= flen; 80 81 if (mctx->pending_len < 4) 82 return; 83 84 mctx->l ^= get_le32(mctx->pending); 85 michael_block(mctx->l, mctx->r); 86 mctx->pending_len = 0; 87 } 88 89 while (len >= 4) { 90 mctx->l ^= get_le32(data); 91 michael_block(mctx->l, mctx->r); 92 data += 4; 93 len -= 4; 94 } 95 96 if (len > 0) { 97 mctx->pending_len = len; 98 memcpy(mctx->pending, data, len); 99 } 100 } 101 102 103 static void michael_final(void *ctx, u8 *out) 104 { 105 struct michael_mic_ctx *mctx = ctx; 106 u8 *data = mctx->pending; 107 108 /* Last block and padding (0x5a, 4..7 x 0) */ 109 switch (mctx->pending_len) { 110 case 0: 111 mctx->l ^= 0x5a; 112 break; 113 case 1: 114 mctx->l ^= data[0] | 0x5a00; 115 break; 116 case 2: 117 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; 118 break; 119 case 3: 120 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | 121 0x5a000000; 122 break; 123 } 124 michael_block(mctx->l, mctx->r); 125 /* l ^= 0; */ 126 michael_block(mctx->l, mctx->r); 127 128 put_le32(out, mctx->l); 129 put_le32(out + 4, mctx->r); 130 } 131 132 133 static int michael_setkey(void *ctx, const u8 *key, unsigned int keylen, 134 u32 *flags) 135 { 136 struct michael_mic_ctx *mctx = ctx; 137 if (keylen != 8) { 138 if (flags) 139 *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; 140 return -EINVAL; 141 } 142 mctx->l = get_le32(key); 143 mctx->r = get_le32(key + 4); 144 return 0; 145 } 146 147 148 static struct crypto_alg michael_mic_alg = { 149 .cra_name = "michael_mic", 150 .cra_flags = CRYPTO_ALG_TYPE_DIGEST, 151 .cra_blocksize = 8, 152 .cra_ctxsize = sizeof(struct michael_mic_ctx), 153 .cra_module = THIS_MODULE, 154 .cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list), 155 .cra_u = { .digest = { 156 .dia_digestsize = 8, 157 .dia_init = michael_init, 158 .dia_update = michael_update, 159 .dia_final = michael_final, 160 .dia_setkey = michael_setkey } } 161 }; 162 163 164 static int __init michael_mic_init(void) 165 { 166 return crypto_register_alg(&michael_mic_alg); 167 } 168 169 170 static void __exit michael_mic_exit(void) 171 { 172 crypto_unregister_alg(&michael_mic_alg); 173 } 174 175 176 module_init(michael_mic_init); 177 module_exit(michael_mic_exit); 178 179 MODULE_LICENSE("GPL v2"); 180 MODULE_DESCRIPTION("Michael MIC"); 181 MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>"); 182