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 32-bit 19 * range. 20 * 21 * IDGEN32 is based on public domain SKIP32 by Greg Rose. 22 */ 23 24 #include <sys/types.h> 25 #include <sys/systm.h> 26 #include <sys/time.h> 27 28 #include <dev/rndvar.h> 29 30 #include <crypto/idgen.h> 31 32 static const u_int8_t idgen32_ftable[256] = { 33 0xa3, 0xd7, 0x09, 0x83, 0xf8, 0x48, 0xf6, 0xf4, 34 0xb3, 0x21, 0x15, 0x78, 0x99, 0xb1, 0xaf, 0xf9, 35 0xe7, 0x2d, 0x4d, 0x8a, 0xce, 0x4c, 0xca, 0x2e, 36 0x52, 0x95, 0xd9, 0x1e, 0x4e, 0x38, 0x44, 0x28, 37 0x0a, 0xdf, 0x02, 0xa0, 0x17, 0xf1, 0x60, 0x68, 38 0x12, 0xb7, 0x7a, 0xc3, 0xe9, 0xfa, 0x3d, 0x53, 39 0x96, 0x84, 0x6b, 0xba, 0xf2, 0x63, 0x9a, 0x19, 40 0x7c, 0xae, 0xe5, 0xf5, 0xf7, 0x16, 0x6a, 0xa2, 41 0x39, 0xb6, 0x7b, 0x0f, 0xc1, 0x93, 0x81, 0x1b, 42 0xee, 0xb4, 0x1a, 0xea, 0xd0, 0x91, 0x2f, 0xb8, 43 0x55, 0xb9, 0xda, 0x85, 0x3f, 0x41, 0xbf, 0xe0, 44 0x5a, 0x58, 0x80, 0x5f, 0x66, 0x0b, 0xd8, 0x90, 45 0x35, 0xd5, 0xc0, 0xa7, 0x33, 0x06, 0x65, 0x69, 46 0x45, 0x00, 0x94, 0x56, 0x6d, 0x98, 0x9b, 0x76, 47 0x97, 0xfc, 0xb2, 0xc2, 0xb0, 0xfe, 0xdb, 0x20, 48 0xe1, 0xeb, 0xd6, 0xe4, 0xdd, 0x47, 0x4a, 0x1d, 49 0x42, 0xed, 0x9e, 0x6e, 0x49, 0x3c, 0xcd, 0x43, 50 0x27, 0xd2, 0x07, 0xd4, 0xde, 0xc7, 0x67, 0x18, 51 0x89, 0xcb, 0x30, 0x1f, 0x8d, 0xc6, 0x8f, 0xaa, 52 0xc8, 0x74, 0xdc, 0xc9, 0x5d, 0x5c, 0x31, 0xa4, 53 0x70, 0x88, 0x61, 0x2c, 0x9f, 0x0d, 0x2b, 0x87, 54 0x50, 0x82, 0x54, 0x64, 0x26, 0x7d, 0x03, 0x40, 55 0x34, 0x4b, 0x1c, 0x73, 0xd1, 0xc4, 0xfd, 0x3b, 56 0xcc, 0xfb, 0x7f, 0xab, 0xe6, 0x3e, 0x5b, 0xa5, 57 0xad, 0x04, 0x23, 0x9c, 0x14, 0x51, 0x22, 0xf0, 58 0x29, 0x79, 0x71, 0x7e, 0xff, 0x8c, 0x0e, 0xe2, 59 0x0c, 0xef, 0xbc, 0x72, 0x75, 0x6f, 0x37, 0xa1, 60 0xec, 0xd3, 0x8e, 0x62, 0x8b, 0x86, 0x10, 0xe8, 61 0x08, 0x77, 0x11, 0xbe, 0x92, 0x4f, 0x24, 0xc5, 62 0x32, 0x36, 0x9d, 0xcf, 0xf3, 0xa6, 0xbb, 0xac, 63 0x5e, 0x6c, 0xa9, 0x13, 0x57, 0x25, 0xb5, 0xe3, 64 0xbd, 0xa8, 0x3a, 0x01, 0x05, 0x59, 0x2a, 0x46 65 }; 66 67 static u_int16_t 68 idgen32_g(u_int8_t *key, int k, u_int16_t w) 69 { 70 u_int8_t g1, g2, g3, g4, g5, g6; 71 u_int o = k * 4; 72 73 g1 = (w >> 8) & 0xff; 74 g2 = w & 0xff; 75 76 g3 = idgen32_ftable[g2 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g1; 77 g4 = idgen32_ftable[g3 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g2; 78 g5 = idgen32_ftable[g4 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g3; 79 g6 = idgen32_ftable[g5 ^ key[o++ & (IDGEN32_KEYLEN - 1)]] ^ g4; 80 81 return (g5 << 8) | g6; 82 } 83 84 static u_int32_t 85 idgen32_permute(struct idgen32_ctx *ctx, u_int32_t in) 86 { 87 u_int i, r; 88 u_int16_t wl, wr; 89 90 wl = (in >> 16) & 0x7fff; 91 wr = in & 0xffff; 92 93 /* Doubled up rounds, with an odd round at the end to swap */ 94 for (i = r = 0; i < IDGEN32_ROUNDS / 2; ++i) { 95 wr ^= (idgen32_g(ctx->id32_key, r, wl) ^ r); 96 r++; 97 wl ^= (idgen32_g(ctx->id32_key, r, wr) ^ r) & 0x7fff; 98 r++; 99 } 100 wr ^= (idgen32_g(ctx->id32_key, r, wl) ^ r); 101 102 return (wl << 16) | wr; 103 } 104 105 static void 106 idgen32_rekey(struct idgen32_ctx *ctx) 107 { 108 ctx->id32_counter = 0; 109 ctx->id32_hibit ^= 0x80000000; 110 ctx->id32_offset = arc4random(); 111 arc4random_buf(ctx->id32_key, sizeof(ctx->id32_key)); 112 ctx->id32_rekey_time = time_second + IDGEN32_REKEY_TIME; 113 } 114 115 void 116 idgen32_init(struct idgen32_ctx *ctx) 117 { 118 bzero(ctx, sizeof(*ctx)); 119 ctx->id32_hibit = arc4random() & 0x80000000; 120 idgen32_rekey(ctx); 121 } 122 123 u_int32_t 124 idgen32(struct idgen32_ctx *ctx) 125 { 126 u_int32_t ret; 127 128 do { 129 /* Rekey a little early to avoid "card counting" attack */ 130 if (ctx->id32_counter > IDGEN32_REKEY_LIMIT || 131 ctx->id32_rekey_time < time_second) 132 idgen32_rekey(ctx); 133 ret = ctx->id32_hibit | idgen32_permute(ctx, 134 (ctx->id32_offset + ctx->id32_counter++) & 0x7fffffff); 135 } while (ret == 0); /* Zero IDs are often special, so avoid */ 136 137 return ret; 138 } 139 140