1/* 2 * Utilities for constant-time cryptography. 3 * 4 * Author: Emilia Kasper (emilia@openssl.org) 5 * Based on previous work by Bodo Moeller, Emilia Kasper, Adam Langley 6 * (Google). 7 * ==================================================================== 8 * Copyright (c) 2014 The OpenSSL Project. All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * "This product includes cryptographic software written by 21 * Eric Young (eay@cryptsoft.com)" 22 * The word 'cryptographic' can be left out if the rouines from the library 23 * being used are not cryptographic related :-). 24 * 4. If you include any Windows specific code (or a derivative thereof) from 25 * the apps directory (application code) you must include an acknowledgement: 26 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 27 * 28 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * The licence and distribution terms for any publically available version or 41 * derivative of this code cannot be changed. i.e. this code cannot simply be 42 * copied and put under another distribution licence 43 * [including the GNU Public Licence.] 44 */ 45 46#include "internal.h" 47 48#include <limits.h> 49#include <stdio.h> 50#include <stdlib.h> 51 52 53static const unsigned int CONSTTIME_TRUE = (unsigned)(~0); 54static const unsigned int CONSTTIME_FALSE = 0; 55static const uint8_t CONSTTIME_TRUE_8 = 0xff; 56static const uint8_t CONSTTIME_FALSE_8 = 0; 57 58static int test_binary_op(unsigned int (*op)(unsigned int a, unsigned int b), 59 const char* op_name, unsigned int a, unsigned int b, 60 int is_true) { 61 unsigned c = op(a, b); 62 if (is_true && c != CONSTTIME_TRUE) { 63 fprintf(stderr, 64 "Test failed for %s(%du, %du): expected %du (TRUE), got %du\n", 65 op_name, a, b, CONSTTIME_TRUE, c); 66 return 1; 67 } else if (!is_true && c != CONSTTIME_FALSE) { 68 fprintf(stderr, 69 "Test failed for %s(%du, %du): expected %du (FALSE), got %du\n", 70 op_name, a, b, CONSTTIME_FALSE, c); 71 return 1; 72 } 73 return 0; 74} 75 76static int test_binary_op_8(uint8_t (*op)(unsigned int a, unsigned int b), 77 const char* op_name, unsigned int a, unsigned int b, 78 int is_true) { 79 uint8_t c = op(a, b); 80 if (is_true && c != CONSTTIME_TRUE_8) { 81 fprintf(stderr, 82 "Test failed for %s(%du, %du): expected %u (TRUE), got %u\n", 83 op_name, a, b, CONSTTIME_TRUE_8, c); 84 return 1; 85 } else if (!is_true && c != CONSTTIME_FALSE_8) { 86 fprintf(stderr, 87 "Test failed for %s(%du, %du): expected %u (FALSE), got %u\n", 88 op_name, a, b, CONSTTIME_FALSE_8, c); 89 return 1; 90 } 91 return 0; 92} 93 94static int test_is_zero(unsigned int a) { 95 unsigned int c = constant_time_is_zero(a); 96 if (a == 0 && c != CONSTTIME_TRUE) { 97 fprintf(stderr, 98 "Test failed for constant_time_is_zero(%du): expected %du (TRUE), " 99 "got %du\n", 100 a, CONSTTIME_TRUE, c); 101 return 1; 102 } else if (a != 0 && c != CONSTTIME_FALSE) { 103 fprintf(stderr, 104 "Test failed for constant_time_is_zero(%du): expected %du (FALSE), " 105 "got %du\n", 106 a, CONSTTIME_FALSE, c); 107 return 1; 108 } 109 return 0; 110} 111 112static int test_is_zero_8(unsigned int a) { 113 uint8_t c = constant_time_is_zero_8(a); 114 if (a == 0 && c != CONSTTIME_TRUE_8) { 115 fprintf(stderr, 116 "Test failed for constant_time_is_zero(%du): expected %u (TRUE), " 117 "got %u\n", 118 a, CONSTTIME_TRUE_8, c); 119 return 1; 120 } else if (a != 0 && c != CONSTTIME_FALSE) { 121 fprintf(stderr, 122 "Test failed for constant_time_is_zero(%du): expected %u (FALSE), " 123 "got %u\n", 124 a, CONSTTIME_FALSE_8, c); 125 return 1; 126 } 127 return 0; 128} 129 130static int test_select(unsigned int a, unsigned int b) { 131 unsigned int selected = constant_time_select(CONSTTIME_TRUE, a, b); 132 if (selected != a) { 133 fprintf(stderr, 134 "Test failed for constant_time_select(%du, %du," 135 "%du): expected %du(first value), got %du\n", 136 CONSTTIME_TRUE, a, b, a, selected); 137 return 1; 138 } 139 selected = constant_time_select(CONSTTIME_FALSE, a, b); 140 if (selected != b) { 141 fprintf(stderr, 142 "Test failed for constant_time_select(%du, %du," 143 "%du): expected %du(second value), got %du\n", 144 CONSTTIME_FALSE, a, b, b, selected); 145 return 1; 146 } 147 return 0; 148} 149 150static int test_select_8(uint8_t a, uint8_t b) { 151 uint8_t selected = constant_time_select_8(CONSTTIME_TRUE_8, a, b); 152 if (selected != a) { 153 fprintf(stderr, 154 "Test failed for constant_time_select(%u, %u," 155 "%u): expected %u(first value), got %u\n", 156 CONSTTIME_TRUE, a, b, a, selected); 157 return 1; 158 } 159 selected = constant_time_select_8(CONSTTIME_FALSE_8, a, b); 160 if (selected != b) { 161 fprintf(stderr, 162 "Test failed for constant_time_select(%u, %u," 163 "%u): expected %u(second value), got %u\n", 164 CONSTTIME_FALSE, a, b, b, selected); 165 return 1; 166 } 167 return 0; 168} 169 170static int test_select_int(int a, int b) { 171 int selected = constant_time_select_int(CONSTTIME_TRUE, a, b); 172 if (selected != a) { 173 fprintf(stderr, 174 "Test failed for constant_time_select(%du, %d," 175 "%d): expected %d(first value), got %d\n", 176 CONSTTIME_TRUE, a, b, a, selected); 177 return 1; 178 } 179 selected = constant_time_select_int(CONSTTIME_FALSE, a, b); 180 if (selected != b) { 181 fprintf(stderr, 182 "Test failed for constant_time_select(%du, %d," 183 "%d): expected %d(second value), got %d\n", 184 CONSTTIME_FALSE, a, b, b, selected); 185 return 1; 186 } 187 return 0; 188} 189 190static int test_eq_int(int a, int b) { 191 unsigned int equal = constant_time_eq_int(a, b); 192 if (a == b && equal != CONSTTIME_TRUE) { 193 fprintf(stderr, 194 "Test failed for constant_time_eq_int(%d, %d): expected %du(TRUE), " 195 "got %du\n", 196 a, b, CONSTTIME_TRUE, equal); 197 return 1; 198 } else if (a != b && equal != CONSTTIME_FALSE) { 199 fprintf(stderr, 200 "Test failed for constant_time_eq_int(%d, %d): expected " 201 "%du(FALSE), got %du\n", 202 a, b, CONSTTIME_FALSE, equal); 203 return 1; 204 } 205 return 0; 206} 207 208static int test_eq_int_8(int a, int b) { 209 uint8_t equal = constant_time_eq_int_8(a, b); 210 if (a == b && equal != CONSTTIME_TRUE_8) { 211 fprintf(stderr, 212 "Test failed for constant_time_eq_int_8(%d, %d): expected " 213 "%u(TRUE), got %u\n", 214 a, b, CONSTTIME_TRUE_8, equal); 215 return 1; 216 } else if (a != b && equal != CONSTTIME_FALSE_8) { 217 fprintf(stderr, 218 "Test failed for constant_time_eq_int_8(%d, %d): expected " 219 "%u(FALSE), got %u\n", 220 a, b, CONSTTIME_FALSE_8, equal); 221 return 1; 222 } 223 return 0; 224} 225 226static unsigned int test_values[] = {0, 1, 1024, 12345, 32000, UINT_MAX / 2 - 1, 227 UINT_MAX / 2, UINT_MAX / 2 + 1, 228 UINT_MAX - 1, UINT_MAX}; 229 230static uint8_t test_values_8[] = {0, 1, 2, 20, 32, 127, 128, 129, 255}; 231 232static int signed_test_values[] = { 233 0, 1, -1, 1024, -1024, 12345, -12345, 234 32000, -32000, INT_MAX, INT_MIN, INT_MAX - 1, INT_MIN + 1}; 235 236int main(int argc, char* argv[]) { 237 unsigned int a, b, i, j; 238 int c, d; 239 uint8_t e, f; 240 int num_failed = 0, num_all = 0; 241 fprintf(stdout, "Testing constant time operations...\n"); 242 243 for (i = 0; i < sizeof(test_values) / sizeof(int); ++i) { 244 a = test_values[i]; 245 num_failed += test_is_zero(a); 246 num_failed += test_is_zero_8(a); 247 num_all += 2; 248 for (j = 0; j < sizeof(test_values) / sizeof(int); ++j) { 249 b = test_values[j]; 250 num_failed += 251 test_binary_op(&constant_time_lt, "constant_time_lt", a, b, a < b); 252 num_failed += test_binary_op_8(&constant_time_lt_8, "constant_time_lt_8", 253 a, b, a < b); 254 num_failed += 255 test_binary_op(&constant_time_lt, "constant_time_lt_8", b, a, b < a); 256 num_failed += test_binary_op_8(&constant_time_lt_8, "constant_time_lt_8", 257 b, a, b < a); 258 num_failed += 259 test_binary_op(&constant_time_ge, "constant_time_ge", a, b, a >= b); 260 num_failed += test_binary_op_8(&constant_time_ge_8, "constant_time_ge_8", 261 a, b, a >= b); 262 num_failed += 263 test_binary_op(&constant_time_ge, "constant_time_ge", b, a, b >= a); 264 num_failed += test_binary_op_8(&constant_time_ge_8, "constant_time_ge_8", 265 b, a, b >= a); 266 num_failed += 267 test_binary_op(&constant_time_eq, "constant_time_eq", a, b, a == b); 268 num_failed += test_binary_op_8(&constant_time_eq_8, "constant_time_eq_8", 269 a, b, a == b); 270 num_failed += 271 test_binary_op(&constant_time_eq, "constant_time_eq", b, a, b == a); 272 num_failed += test_binary_op_8(&constant_time_eq_8, "constant_time_eq_8", 273 b, a, b == a); 274 num_failed += test_select(a, b); 275 num_all += 13; 276 } 277 } 278 279 for (i = 0; i < sizeof(signed_test_values) / sizeof(int); ++i) { 280 c = signed_test_values[i]; 281 for (j = 0; j < sizeof(signed_test_values) / sizeof(int); ++j) { 282 d = signed_test_values[j]; 283 num_failed += test_select_int(c, d); 284 num_failed += test_eq_int(c, d); 285 num_failed += test_eq_int_8(c, d); 286 num_all += 3; 287 } 288 } 289 290 for (i = 0; i < sizeof(test_values_8); ++i) { 291 e = test_values_8[i]; 292 for (j = 0; j < sizeof(test_values_8); ++j) { 293 f = test_values_8[j]; 294 num_failed += test_select_8(e, f); 295 num_all += 1; 296 } 297 } 298 299 if (!num_failed) { 300 fprintf(stdout, "ok (ran %d tests)\n", num_all); 301 fprintf(stdout, "PASS\n"); 302 return EXIT_SUCCESS; 303 } else { 304 fprintf(stdout, "%d of %d tests failed!\n", num_failed, num_all); 305 return EXIT_FAILURE; 306 } 307} 308