1 /* 2 * Copyright (c) 2008 Damien Miller <djm@mindrot.org> 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 /* 18 * IDGEN32: non-repeating ID generation covering an almost maximal 19 * 32 bit range. 20 * Based on public domain SKIP32 by Greg Rose. 21 */ 22 23 #include <sys/types.h> 24 #include <sys/systm.h> 25 #include <sys/time.h> 26 27 #include <dev/rndvar.h> 28 29 #include <crypto/idgen.h> 30 31 static const u_int8_t ftable[256] = { 32 0xa3, 0xd7, 0x09, 0x83, 0xf8, 0x48, 0xf6, 0xf4, 33 0xb3, 0x21, 0x15, 0x78, 0x99, 0xb1, 0xaf, 0xf9, 34 0xe7, 0x2d, 0x4d, 0x8a, 0xce, 0x4c, 0xca, 0x2e, 35 0x52, 0x95, 0xd9, 0x1e, 0x4e, 0x38, 0x44, 0x28, 36 0x0a, 0xdf, 0x02, 0xa0, 0x17, 0xf1, 0x60, 0x68, 37 0x12, 0xb7, 0x7a, 0xc3, 0xe9, 0xfa, 0x3d, 0x53, 38 0x96, 0x84, 0x6b, 0xba, 0xf2, 0x63, 0x9a, 0x19, 39 0x7c, 0xae, 0xe5, 0xf5, 0xf7, 0x16, 0x6a, 0xa2, 40 0x39, 0xb6, 0x7b, 0x0f, 0xc1, 0x93, 0x81, 0x1b, 41 0xee, 0xb4, 0x1a, 0xea, 0xd0, 0x91, 0x2f, 0xb8, 42 0x55, 0xb9, 0xda, 0x85, 0x3f, 0x41, 0xbf, 0xe0, 43 0x5a, 0x58, 0x80, 0x5f, 0x66, 0x0b, 0xd8, 0x90, 44 0x35, 0xd5, 0xc0, 0xa7, 0x33, 0x06, 0x65, 0x69, 45 0x45, 0x00, 0x94, 0x56, 0x6d, 0x98, 0x9b, 0x76, 46 0x97, 0xfc, 0xb2, 0xc2, 0xb0, 0xfe, 0xdb, 0x20, 47 0xe1, 0xeb, 0xd6, 0xe4, 0xdd, 0x47, 0x4a, 0x1d, 48 0x42, 0xed, 0x9e, 0x6e, 0x49, 0x3c, 0xcd, 0x43, 49 0x27, 0xd2, 0x07, 0xd4, 0xde, 0xc7, 0x67, 0x18, 50 0x89, 0xcb, 0x30, 0x1f, 0x8d, 0xc6, 0x8f, 0xaa, 51 0xc8, 0x74, 0xdc, 0xc9, 0x5d, 0x5c, 0x31, 0xa4, 52 0x70, 0x88, 0x61, 0x2c, 0x9f, 0x0d, 0x2b, 0x87, 53 0x50, 0x82, 0x54, 0x64, 0x26, 0x7d, 0x03, 0x40, 54 0x34, 0x4b, 0x1c, 0x73, 0xd1, 0xc4, 0xfd, 0x3b, 55 0xcc, 0xfb, 0x7f, 0xab, 0xe6, 0x3e, 0x5b, 0xa5, 56 0xad, 0x04, 0x23, 0x9c, 0x14, 0x51, 0x22, 0xf0, 57 0x29, 0x79, 0x71, 0x7e, 0xff, 0x8c, 0x0e, 0xe2, 58 0x0c, 0xef, 0xbc, 0x72, 0x75, 0x6f, 0x37, 0xa1, 59 0xec, 0xd3, 0x8e, 0x62, 0x8b, 0x86, 0x10, 0xe8, 60 0x08, 0x77, 0x11, 0xbe, 0x92, 0x4f, 0x24, 0xc5, 61 0x32, 0x36, 0x9d, 0xcf, 0xf3, 0xa6, 0xbb, 0xac, 62 0x5e, 0x6c, 0xa9, 0x13, 0x57, 0x25, 0xb5, 0xe3, 63 0xbd, 0xa8, 0x3a, 0x01, 0x05, 0x59, 0x2a, 0x46 64 }; 65 66 static u_int16_t 67 idgen32_g(u_int8_t *key, int k, u_int16_t w) 68 { 69 u_int8_t g1, g2, g3, g4, g5, g6; 70 u_int o = k * 4; 71 72 g1 = (w >> 8) & 0xff; 73 g2 = w & 0xff; 74 75 g3 = ftable[g2 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g1; 76 g4 = ftable[g3 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g2; 77 g5 = ftable[g4 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g3; 78 g6 = ftable[g5 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g4; 79 80 return (g5 << 8) | g6; 81 } 82 83 static u_int32_t 84 idgen32_permute(u_int8_t key[IDGEN32_KEYLEN], u_int32_t in) 85 { 86 u_int i, r; 87 u_int16_t wl, wr; 88 89 wl = (in >> 16) & 0x7fff; 90 wr = in & 0xffff; 91 92 /* Doubled up rounds, with an odd round at the end to swap */ 93 for (i = r = 0; i < IDGEN32_ROUNDS / 2; ++i) { 94 wr ^= (idgen32_g(key, r, wl) ^ r); 95 r++; 96 wl ^= (idgen32_g(key, r, wr) ^ r) & 0x7fff; 97 r++; 98 } 99 wr ^= (idgen32_g(key, r, wl) ^ r); 100 101 return (wl << 16) | wr; 102 } 103 104 static void 105 idgen32_rekey(struct idgen32_ctx *ctx) 106 { 107 ctx->id_counter = 0; 108 ctx->id_hibit ^= 0x80000000; 109 ctx->id_offset = arc4random(); 110 arc4random_buf(ctx->id_key, sizeof(ctx->id_key)); 111 ctx->id_rekey_time = time_second + IDGEN32_REKEY_TIME; 112 } 113 114 void 115 idgen32_init(struct idgen32_ctx *ctx) 116 { 117 bzero(ctx, sizeof(ctx)); 118 ctx->id_hibit = arc4random() & 0x80000000; 119 idgen32_rekey(ctx); 120 } 121 122 u_int32_t 123 idgen32(struct idgen32_ctx *ctx) 124 { 125 u_int32_t ret; 126 127 /* Avoid emitting a zero ID as they often have special meaning */ 128 do { 129 ret = idgen32_permute(ctx->id_key, 130 ctx->id_offset + ctx->id_counter++); 131 132 /* Rekey a little early to avoid "card counting" attack */ 133 if (ctx->id_counter > IDGEN32_REKEY_LIMIT || 134 ctx->id_rekey_time > time_second) 135 idgen32_rekey(ctx); 136 } while (ret == 0); 137 138 return ret | ctx->id_hibit; 139 } 140