1 /* $OpenBSD: michael.c,v 1.2 2008/07/21 19:52:45 damien Exp $ */ 2 3 /* 4 * Copyright (c) 2005, 2006 Reyk Floeter <reyk@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 /* 20 * Implementation of the Michael MIC as defined in IEEE 802.11i for TKIP. 21 * The MIC generates a 64bit digest, which shouldn't be used for any other 22 * applications except TKIP. 23 */ 24 25 #include <sys/param.h> 26 #include <sys/systm.h> 27 28 #include <crypto/michael.h> 29 30 #define ROL(n, x) (((x) << (n)) | ((x) >> (32 - (n)))) 31 #define ROR(n, x) (((x) >> (n)) | ((x) << (32 - (n)))) 32 #define XSWAP(x) (((x) & 0xff00ff00UL) >> 8 | ((x) & 0x00ff00ffUL) << 8) 33 34 #if defined(__STRICT_ALIGNMENT) || _BYTE_ORDER != _LITTLE_ENDIAN 35 #define GETLE32(x) ((x)[0] | (x)[1] << 8 | (x)[2] << 16 | (x)[3] << 24) 36 #define PUTLE32(x, v) ((x)[0] = (u_int8_t)(v), \ 37 (x)[1] = (u_int8_t)((v) >> 8), \ 38 (x)[2] = (u_int8_t)((v) >> 16), \ 39 (x)[3] = (u_int8_t)((v) >> 24)) 40 #else 41 #define GETLE32(x) (*((u_int32_t *)(x))) 42 #define PUTLE32(x, v) (*((u_int32_t *)(x)) = (v)) 43 #endif 44 45 #define MICHAEL_BLOCK(l, r) do { \ 46 r ^= ROL(17, l); \ 47 l += r; \ 48 r ^= XSWAP(l); \ 49 l += r; \ 50 r ^= ROL(3, l); \ 51 l += r; \ 52 r ^= ROR(2, l); \ 53 l += r; \ 54 } while (0) 55 56 void 57 michael_init(MICHAEL_CTX *ctx) 58 { 59 bzero(ctx, sizeof(MICHAEL_CTX)); 60 } 61 62 void 63 michael_update(MICHAEL_CTX *ctx, const u_int8_t *data, u_int len) 64 { 65 int i; 66 67 for (i = 0; i < len; i++) { 68 ctx->michael_state |= data[i] << (ctx->michael_count << 3); 69 ctx->michael_count++; 70 71 if (ctx->michael_count >= MICHAEL_RAW_BLOCK_LENGTH) { 72 ctx->michael_l ^= ctx->michael_state; 73 MICHAEL_BLOCK(ctx->michael_l, ctx->michael_r); 74 ctx->michael_state = ctx->michael_count = 0; 75 } 76 } 77 } 78 79 void 80 michael_final(u_int8_t digest[MICHAEL_DIGEST_LENGTH], MICHAEL_CTX *ctx) 81 { 82 static const u_int8_t pad[] = 83 { 0x5a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; 84 85 michael_update(ctx, pad, sizeof(pad)); 86 87 PUTLE32(digest, ctx->michael_l); 88 PUTLE32(digest + MICHAEL_RAW_BLOCK_LENGTH, ctx->michael_r); 89 } 90 91 void 92 michael_key(const u_int8_t *key, MICHAEL_CTX *ctx) 93 { 94 ctx->michael_l = ctx->michael_key[0] = 95 GETLE32(key); 96 ctx->michael_r = ctx->michael_key[1] = 97 GETLE32(key + MICHAEL_RAW_BLOCK_LENGTH); 98 } 99