1 /** 2 * \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion 3 * 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 * 7 * This file is provided under the Apache License 2.0, or the 8 * GNU General Public License v2.0 or later. 9 * 10 * ********** 11 * Apache License 2.0: 12 * 13 * Licensed under the Apache License, Version 2.0 (the "License"); you may 14 * not use this file except in compliance with the License. 15 * You may obtain a copy of the License at 16 * 17 * http://www.apache.org/licenses/LICENSE-2.0 18 * 19 * Unless required by applicable law or agreed to in writing, software 20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 22 * See the License for the specific language governing permissions and 23 * limitations under the License. 24 * 25 * ********** 26 * 27 * ********** 28 * GNU General Public License v2.0 or later: 29 * 30 * This program is free software; you can redistribute it and/or modify 31 * it under the terms of the GNU General Public License as published by 32 * the Free Software Foundation; either version 2 of the License, or 33 * (at your option) any later version. 34 * 35 * This program is distributed in the hope that it will be useful, 36 * but WITHOUT ANY WARRANTY; without even the implied warranty of 37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 38 * GNU General Public License for more details. 39 * 40 * You should have received a copy of the GNU General Public License along 41 * with this program; if not, write to the Free Software Foundation, Inc., 42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 43 * 44 * ********** 45 * 46 * This file is part of mbed TLS (https://tls.mbed.org) 47 */ 48 /* 49 * The HAVEGE RNG was designed by Andre Seznec in 2002. 50 * 51 * http://www.irisa.fr/caps/projects/hipsor/publi.php 52 * 53 * Contact: seznec(at)irisa_dot_fr - orocheco(at)irisa_dot_fr 54 */ 55 56 #if !defined(MBEDTLS_CONFIG_FILE) 57 #include "mbedtls/config.h" 58 #else 59 #include MBEDTLS_CONFIG_FILE 60 #endif 61 62 #if defined(MBEDTLS_HAVEGE_C) 63 64 #include "mbedtls/havege.h" 65 #include "mbedtls/timing.h" 66 67 #include <limits.h> 68 #include <string.h> 69 70 /* If int isn't capable of storing 2^32 distinct values, the code of this 71 * module may cause a processor trap or a miscalculation. If int is more 72 * than 32 bits, the code may not calculate the intended values. */ 73 #if INT_MIN + 1 != -0x7fffffff 74 #error "The HAVEGE module requires int to be exactly 32 bits, with INT_MIN = -2^31." 75 #endif 76 #if UINT_MAX != 0xffffffff 77 #error "The HAVEGE module requires unsigned to be exactly 32 bits." 78 #endif 79 80 /* Implementation that should never be optimized out by the compiler */ 81 static void mbedtls_zeroize( void *v, size_t n ) { 82 volatile unsigned char *p = v; while( n-- ) *p++ = 0; 83 } 84 85 /* ------------------------------------------------------------------------ 86 * On average, one iteration accesses two 8-word blocks in the havege WALK 87 * table, and generates 16 words in the RES array. 88 * 89 * The data read in the WALK table is updated and permuted after each use. 90 * The result of the hardware clock counter read is used for this update. 91 * 92 * 25 conditional tests are present. The conditional tests are grouped in 93 * two nested groups of 12 conditional tests and 1 test that controls the 94 * permutation; on average, there should be 6 tests executed and 3 of them 95 * should be mispredicted. 96 * ------------------------------------------------------------------------ 97 */ 98 99 #define SWAP(X,Y) { unsigned *T = (X); (X) = (Y); (Y) = T; } 100 101 #define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; 102 #define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; 103 104 #define TST1_LEAVE U1++; } 105 #define TST2_LEAVE U2++; } 106 107 #define ONE_ITERATION \ 108 \ 109 PTEST = PT1 >> 20; \ 110 \ 111 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 112 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 113 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 114 \ 115 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 116 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 117 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 118 \ 119 PTX = (PT1 >> 18) & 7; \ 120 PT1 &= 0x1FFF; \ 121 PT2 &= 0x1FFF; \ 122 CLK = (unsigned) mbedtls_timing_hardclock(); \ 123 \ 124 i = 0; \ 125 A = &WALK[PT1 ]; RES[i++] ^= *A; \ 126 B = &WALK[PT2 ]; RES[i++] ^= *B; \ 127 C = &WALK[PT1 ^ 1]; RES[i++] ^= *C; \ 128 D = &WALK[PT2 ^ 4]; RES[i++] ^= *D; \ 129 \ 130 IN = (*A >> (1)) ^ (*A << (31)) ^ CLK; \ 131 *A = (*B >> (2)) ^ (*B << (30)) ^ CLK; \ 132 *B = IN ^ U1; \ 133 *C = (*C >> (3)) ^ (*C << (29)) ^ CLK; \ 134 *D = (*D >> (4)) ^ (*D << (28)) ^ CLK; \ 135 \ 136 A = &WALK[PT1 ^ 2]; RES[i++] ^= *A; \ 137 B = &WALK[PT2 ^ 2]; RES[i++] ^= *B; \ 138 C = &WALK[PT1 ^ 3]; RES[i++] ^= *C; \ 139 D = &WALK[PT2 ^ 6]; RES[i++] ^= *D; \ 140 \ 141 if( PTEST & 1 ) SWAP( A, C ); \ 142 \ 143 IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \ 144 *A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \ 145 *B = IN; CLK = (unsigned) mbedtls_timing_hardclock(); \ 146 *C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \ 147 *D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \ 148 \ 149 A = &WALK[PT1 ^ 4]; \ 150 B = &WALK[PT2 ^ 1]; \ 151 \ 152 PTEST = PT2 >> 1; \ 153 \ 154 PT2 = (RES[(i - 8) ^ PTY] ^ WALK[PT2 ^ PTY ^ 7]); \ 155 PT2 = ((PT2 & 0x1FFF) & (~8)) ^ ((PT1 ^ 8) & 0x8); \ 156 PTY = (PT2 >> 10) & 7; \ 157 \ 158 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 159 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 160 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 161 \ 162 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 163 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 164 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 165 \ 166 C = &WALK[PT1 ^ 5]; \ 167 D = &WALK[PT2 ^ 5]; \ 168 \ 169 RES[i++] ^= *A; \ 170 RES[i++] ^= *B; \ 171 RES[i++] ^= *C; \ 172 RES[i++] ^= *D; \ 173 \ 174 IN = (*A >> ( 9)) ^ (*A << (23)) ^ CLK; \ 175 *A = (*B >> (10)) ^ (*B << (22)) ^ CLK; \ 176 *B = IN ^ U2; \ 177 *C = (*C >> (11)) ^ (*C << (21)) ^ CLK; \ 178 *D = (*D >> (12)) ^ (*D << (20)) ^ CLK; \ 179 \ 180 A = &WALK[PT1 ^ 6]; RES[i++] ^= *A; \ 181 B = &WALK[PT2 ^ 3]; RES[i++] ^= *B; \ 182 C = &WALK[PT1 ^ 7]; RES[i++] ^= *C; \ 183 D = &WALK[PT2 ^ 7]; RES[i++] ^= *D; \ 184 \ 185 IN = (*A >> (13)) ^ (*A << (19)) ^ CLK; \ 186 *A = (*B >> (14)) ^ (*B << (18)) ^ CLK; \ 187 *B = IN; \ 188 *C = (*C >> (15)) ^ (*C << (17)) ^ CLK; \ 189 *D = (*D >> (16)) ^ (*D << (16)) ^ CLK; \ 190 \ 191 PT1 = ( RES[( i - 8 ) ^ PTX] ^ \ 192 WALK[PT1 ^ PTX ^ 7] ) & (~1); \ 193 PT1 ^= (PT2 ^ 0x10) & 0x10; \ 194 \ 195 for( n++, i = 0; i < 16; i++ ) \ 196 POOL[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i]; 197 198 /* 199 * Entropy gathering function 200 */ 201 static void havege_fill( mbedtls_havege_state *hs ) 202 { 203 unsigned i, n = 0; 204 unsigned U1, U2, *A, *B, *C, *D; 205 unsigned PT1, PT2, *WALK, *POOL, RES[16]; 206 unsigned PTX, PTY, CLK, PTEST, IN; 207 208 WALK = (unsigned *) hs->WALK; 209 POOL = (unsigned *) hs->pool; 210 PT1 = hs->PT1; 211 PT2 = hs->PT2; 212 213 PTX = U1 = 0; 214 PTY = U2 = 0; 215 216 (void)PTX; 217 218 memset( RES, 0, sizeof( RES ) ); 219 220 while( n < MBEDTLS_HAVEGE_COLLECT_SIZE * 4 ) 221 { 222 ONE_ITERATION 223 ONE_ITERATION 224 ONE_ITERATION 225 ONE_ITERATION 226 } 227 228 hs->PT1 = PT1; 229 hs->PT2 = PT2; 230 231 hs->offset[0] = 0; 232 hs->offset[1] = MBEDTLS_HAVEGE_COLLECT_SIZE / 2; 233 } 234 235 /* 236 * HAVEGE initialization 237 */ 238 void mbedtls_havege_init( mbedtls_havege_state *hs ) 239 { 240 memset( hs, 0, sizeof( mbedtls_havege_state ) ); 241 242 havege_fill( hs ); 243 } 244 245 void mbedtls_havege_free( mbedtls_havege_state *hs ) 246 { 247 if( hs == NULL ) 248 return; 249 250 mbedtls_zeroize( hs, sizeof( mbedtls_havege_state ) ); 251 } 252 253 /* 254 * HAVEGE rand function 255 */ 256 int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len ) 257 { 258 int val; 259 size_t use_len; 260 mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng; 261 unsigned char *p = buf; 262 263 while( len > 0 ) 264 { 265 use_len = len; 266 if( use_len > sizeof(int) ) 267 use_len = sizeof(int); 268 269 if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE ) 270 havege_fill( hs ); 271 272 val = hs->pool[hs->offset[0]++]; 273 val ^= hs->pool[hs->offset[1]++]; 274 275 memcpy( p, &val, use_len ); 276 277 len -= use_len; 278 p += use_len; 279 } 280 281 return( 0 ); 282 } 283 284 #endif /* MBEDTLS_HAVEGE_C */ 285