1 /** 2 * \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion 3 * 4 * Copyright The Mbed TLS Contributors 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 /* 47 * The HAVEGE RNG was designed by Andre Seznec in 2002. 48 * 49 * http://www.irisa.fr/caps/projects/hipsor/publi.php 50 * 51 * Contact: seznec(at)irisa_dot_fr - orocheco(at)irisa_dot_fr 52 */ 53 54 #if !defined(MBEDTLS_CONFIG_FILE) 55 #include "mbedtls/config.h" 56 #else 57 #include MBEDTLS_CONFIG_FILE 58 #endif 59 60 #if defined(MBEDTLS_HAVEGE_C) 61 62 #include "mbedtls/havege.h" 63 #include "mbedtls/timing.h" 64 #include "mbedtls/platform_util.h" 65 66 #include <limits.h> 67 #include <string.h> 68 69 /* If int isn't capable of storing 2^32 distinct values, the code of this 70 * module may cause a processor trap or a miscalculation. If int is more 71 * than 32 bits, the code may not calculate the intended values. */ 72 #if INT_MIN + 1 != -0x7fffffff 73 #error "The HAVEGE module requires int to be exactly 32 bits, with INT_MIN = -2^31." 74 #endif 75 #if UINT_MAX != 0xffffffff 76 #error "The HAVEGE module requires unsigned to be exactly 32 bits." 77 #endif 78 79 /* ------------------------------------------------------------------------ 80 * On average, one iteration accesses two 8-word blocks in the havege WALK 81 * table, and generates 16 words in the RES array. 82 * 83 * The data read in the WALK table is updated and permuted after each use. 84 * The result of the hardware clock counter read is used for this update. 85 * 86 * 25 conditional tests are present. The conditional tests are grouped in 87 * two nested groups of 12 conditional tests and 1 test that controls the 88 * permutation; on average, there should be 6 tests executed and 3 of them 89 * should be mispredicted. 90 * ------------------------------------------------------------------------ 91 */ 92 93 #define SWAP(X,Y) { unsigned *T = (X); (X) = (Y); (Y) = T; } 94 95 #define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; 96 #define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; 97 98 #define TST1_LEAVE U1++; } 99 #define TST2_LEAVE U2++; } 100 101 #define ONE_ITERATION \ 102 \ 103 PTEST = PT1 >> 20; \ 104 \ 105 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 106 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 107 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 108 \ 109 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 110 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 111 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 112 \ 113 PTX = (PT1 >> 18) & 7; \ 114 PT1 &= 0x1FFF; \ 115 PT2 &= 0x1FFF; \ 116 CLK = (unsigned) mbedtls_timing_hardclock(); \ 117 \ 118 i = 0; \ 119 A = &WALK[PT1 ]; RES[i++] ^= *A; \ 120 B = &WALK[PT2 ]; RES[i++] ^= *B; \ 121 C = &WALK[PT1 ^ 1]; RES[i++] ^= *C; \ 122 D = &WALK[PT2 ^ 4]; RES[i++] ^= *D; \ 123 \ 124 IN = (*A >> (1)) ^ (*A << (31)) ^ CLK; \ 125 *A = (*B >> (2)) ^ (*B << (30)) ^ CLK; \ 126 *B = IN ^ U1; \ 127 *C = (*C >> (3)) ^ (*C << (29)) ^ CLK; \ 128 *D = (*D >> (4)) ^ (*D << (28)) ^ CLK; \ 129 \ 130 A = &WALK[PT1 ^ 2]; RES[i++] ^= *A; \ mbedtls_gcm_init(mbedtls_gcm_context * ctx)131 B = &WALK[PT2 ^ 2]; RES[i++] ^= *B; \ 132 C = &WALK[PT1 ^ 3]; RES[i++] ^= *C; \ 133 D = &WALK[PT2 ^ 6]; RES[i++] ^= *D; \ 134 \ 135 if( PTEST & 1 ) SWAP( A, C ); \ 136 \ 137 IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \ 138 *A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \ 139 *B = IN; CLK = (unsigned) mbedtls_timing_hardclock(); \ 140 *C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \ 141 *D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \ 142 \ 143 A = &WALK[PT1 ^ 4]; \ 144 B = &WALK[PT2 ^ 1]; \ gcm_gen_table(mbedtls_gcm_context * ctx)145 \ 146 PTEST = PT2 >> 1; \ 147 \ 148 PT2 = (RES[(i - 8) ^ PTY] ^ WALK[PT2 ^ PTY ^ 7]); \ 149 PT2 = ((PT2 & 0x1FFF) & (~8)) ^ ((PT1 ^ 8) & 0x8); \ 150 PTY = (PT2 >> 10) & 7; \ 151 \ 152 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 153 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 154 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 155 \ 156 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 157 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 158 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 159 \ 160 C = &WALK[PT1 ^ 5]; \ 161 D = &WALK[PT2 ^ 5]; \ 162 \ 163 RES[i++] ^= *A; \ 164 RES[i++] ^= *B; \ 165 RES[i++] ^= *C; \ 166 RES[i++] ^= *D; \ 167 \ 168 IN = (*A >> ( 9)) ^ (*A << (23)) ^ CLK; \ 169 *A = (*B >> (10)) ^ (*B << (22)) ^ CLK; \ 170 *B = IN ^ U2; \ 171 *C = (*C >> (11)) ^ (*C << (21)) ^ CLK; \ 172 *D = (*D >> (12)) ^ (*D << (20)) ^ CLK; \ 173 \ 174 A = &WALK[PT1 ^ 6]; RES[i++] ^= *A; \ 175 B = &WALK[PT2 ^ 3]; RES[i++] ^= *B; \ 176 C = &WALK[PT1 ^ 7]; RES[i++] ^= *C; \ 177 D = &WALK[PT2 ^ 7]; RES[i++] ^= *D; \ 178 \ 179 IN = (*A >> (13)) ^ (*A << (19)) ^ CLK; \ 180 *A = (*B >> (14)) ^ (*B << (18)) ^ CLK; \ 181 *B = IN; \ 182 *C = (*C >> (15)) ^ (*C << (17)) ^ CLK; \ 183 *D = (*D >> (16)) ^ (*D << (16)) ^ CLK; \ 184 \ 185 PT1 = ( RES[( i - 8 ) ^ PTX] ^ \ 186 WALK[PT1 ^ PTX ^ 7] ) & (~1); \ 187 PT1 ^= (PT2 ^ 0x10) & 0x10; \ 188 \ 189 for( n++, i = 0; i < 16; i++ ) \ 190 POOL[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i]; 191 192 /* 193 * Entropy gathering function 194 */ 195 static void havege_fill( mbedtls_havege_state *hs ) 196 { 197 unsigned i, n = 0; 198 unsigned U1, U2, *A, *B, *C, *D; 199 unsigned PT1, PT2, *WALK, *POOL, RES[16]; 200 unsigned PTX, PTY, CLK, PTEST, IN; 201 202 WALK = (unsigned *) hs->WALK; 203 POOL = (unsigned *) hs->pool; 204 PT1 = hs->PT1; mbedtls_gcm_setkey(mbedtls_gcm_context * ctx,mbedtls_cipher_id_t cipher,const unsigned char * key,unsigned int keybits)205 PT2 = hs->PT2; 206 207 PTX = U1 = 0; 208 PTY = U2 = 0; 209 210 (void)PTX; 211 212 memset( RES, 0, sizeof( RES ) ); 213 214 while( n < MBEDTLS_HAVEGE_COLLECT_SIZE * 4 ) 215 { 216 ONE_ITERATION 217 ONE_ITERATION 218 ONE_ITERATION 219 ONE_ITERATION 220 } 221 222 hs->PT1 = PT1; 223 hs->PT2 = PT2; 224 225 hs->offset[0] = 0; 226 hs->offset[1] = MBEDTLS_HAVEGE_COLLECT_SIZE / 2; 227 } 228 229 /* 230 * HAVEGE initialization 231 */ 232 void mbedtls_havege_init( mbedtls_havege_state *hs ) 233 { 234 memset( hs, 0, sizeof( mbedtls_havege_state ) ); 235 236 havege_fill( hs ); 237 } 238 239 void mbedtls_havege_free( mbedtls_havege_state *hs ) 240 { 241 if( hs == NULL ) 242 return; 243 244 mbedtls_platform_zeroize( hs, sizeof( mbedtls_havege_state ) ); 245 } 246 247 /* 248 * HAVEGE rand function 249 */ 250 int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len ) 251 { 252 int val; 253 size_t use_len; 254 mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng; 255 unsigned char *p = buf; 256 257 while( len > 0 ) gcm_mult(mbedtls_gcm_context * ctx,const unsigned char x[16],unsigned char output[16])258 { 259 use_len = len; 260 if( use_len > sizeof(int) ) 261 use_len = sizeof(int); 262 263 if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE ) 264 havege_fill( hs ); 265 266 val = hs->pool[hs->offset[0]++]; 267 val ^= hs->pool[hs->offset[1]++]; 268 269 memcpy( p, &val, use_len ); 270 271 len -= use_len; 272 p += use_len; 273 } 274 275 return( 0 ); 276 } 277 278 #endif /* MBEDTLS_HAVEGE_C */ 279