1 /* 2 * Cryptographic API 3 * 4 * Michael MIC (IEEE 802.11i/TKIP) keyed digest 5 * 6 * Copyright (c) 2004 Jouni Malinen <j@w1.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 #include <crypto/internal/hash.h> 13 #include <asm/byteorder.h> 14 #include <linux/init.h> 15 #include <linux/module.h> 16 #include <linux/string.h> 17 #include <linux/types.h> 18 19 20 struct michael_mic_ctx { 21 u32 l, r; 22 }; 23 24 struct michael_mic_desc_ctx { 25 u8 pending[4]; 26 size_t pending_len; 27 28 u32 l, r; 29 }; 30 31 static inline u32 xswap(u32 val) 32 { 33 return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8); 34 } 35 36 37 #define michael_block(l, r) \ 38 do { \ 39 r ^= rol32(l, 17); \ 40 l += r; \ 41 r ^= xswap(l); \ 42 l += r; \ 43 r ^= rol32(l, 3); \ 44 l += r; \ 45 r ^= ror32(l, 2); \ 46 l += r; \ 47 } while (0) 48 49 50 static int michael_init(struct shash_desc *desc) 51 { 52 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); 53 struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm); 54 mctx->pending_len = 0; 55 mctx->l = ctx->l; 56 mctx->r = ctx->r; 57 58 return 0; 59 } 60 61 62 static int michael_update(struct shash_desc *desc, const u8 *data, 63 unsigned int len) 64 { 65 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); 66 const __le32 *src; 67 68 if (mctx->pending_len) { 69 int flen = 4 - mctx->pending_len; 70 if (flen > len) 71 flen = len; 72 memcpy(&mctx->pending[mctx->pending_len], data, flen); 73 mctx->pending_len += flen; 74 data += flen; 75 len -= flen; 76 77 if (mctx->pending_len < 4) 78 return 0; 79 80 src = (const __le32 *)mctx->pending; 81 mctx->l ^= le32_to_cpup(src); 82 michael_block(mctx->l, mctx->r); 83 mctx->pending_len = 0; 84 } 85 86 src = (const __le32 *)data; 87 88 while (len >= 4) { 89 mctx->l ^= le32_to_cpup(src++); 90 michael_block(mctx->l, mctx->r); 91 len -= 4; 92 } 93 94 if (len > 0) { 95 mctx->pending_len = len; 96 memcpy(mctx->pending, src, len); 97 } 98 99 return 0; 100 } 101 102 103 static int michael_final(struct shash_desc *desc, u8 *out) 104 { 105 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); 106 u8 *data = mctx->pending; 107 __le32 *dst = (__le32 *)out; 108 109 /* Last block and padding (0x5a, 4..7 x 0) */ 110 switch (mctx->pending_len) { 111 case 0: 112 mctx->l ^= 0x5a; 113 break; 114 case 1: 115 mctx->l ^= data[0] | 0x5a00; 116 break; 117 case 2: 118 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; 119 break; 120 case 3: 121 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | 122 0x5a000000; 123 break; 124 } 125 michael_block(mctx->l, mctx->r); 126 /* l ^= 0; */ 127 michael_block(mctx->l, mctx->r); 128 129 dst[0] = cpu_to_le32(mctx->l); 130 dst[1] = cpu_to_le32(mctx->r); 131 132 return 0; 133 } 134 135 136 static int michael_setkey(struct crypto_shash *tfm, const u8 *key, 137 unsigned int keylen) 138 { 139 struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm); 140 141 const __le32 *data = (const __le32 *)key; 142 143 if (keylen != 8) { 144 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); 145 return -EINVAL; 146 } 147 148 mctx->l = le32_to_cpu(data[0]); 149 mctx->r = le32_to_cpu(data[1]); 150 return 0; 151 } 152 153 static struct shash_alg alg = { 154 .digestsize = 8, 155 .setkey = michael_setkey, 156 .init = michael_init, 157 .update = michael_update, 158 .final = michael_final, 159 .descsize = sizeof(struct michael_mic_desc_ctx), 160 .base = { 161 .cra_name = "michael_mic", 162 .cra_blocksize = 8, 163 .cra_alignmask = 3, 164 .cra_ctxsize = sizeof(struct michael_mic_ctx), 165 .cra_module = THIS_MODULE, 166 } 167 }; 168 169 static int __init michael_mic_init(void) 170 { 171 return crypto_register_shash(&alg); 172 } 173 174 175 static void __exit michael_mic_exit(void) 176 { 177 crypto_unregister_shash(&alg); 178 } 179 180 181 module_init(michael_mic_init); 182 module_exit(michael_mic_exit); 183 184 MODULE_LICENSE("GPL v2"); 185 MODULE_DESCRIPTION("Michael MIC"); 186 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>"); 187 MODULE_ALIAS_CRYPTO("michael_mic"); 188