1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2011 The FreeBSD Project. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 /* Based on:
29 * SHA256-based Unix crypt implementation. Released into the Public Domain by
30 * Ulrich Drepper <drepper@redhat.com>. */
31
32 #include <sys/cdefs.h>
33 #include <sys/endian.h>
34 #include <sys/param.h>
35
36 #include <errno.h>
37 #include <limits.h>
38 #include <sha256.h>
39 #include <stdbool.h>
40 #include <stdint.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <strings.h>
45
46 #include "crypt.h"
47
48 /* Define our magic string to mark salt for SHA256 "encryption" replacement. */
49 static const char sha256_salt_prefix[] = "$5$";
50
51 /* Prefix for optional rounds specification. */
52 static const char sha256_rounds_prefix[] = "rounds=";
53
54 /* Maximum salt string length. */
55 #define SALT_LEN_MAX 16
56 /* Default number of rounds if not explicitly specified. */
57 #define ROUNDS_DEFAULT 5000
58 /* Minimum number of rounds. */
59 #define ROUNDS_MIN 1000
60 /* Maximum number of rounds. */
61 #define ROUNDS_MAX 999999999
62
63 int
crypt_sha256(const char * key,const char * salt,char * buffer)64 crypt_sha256(const char *key, const char *salt, char *buffer)
65 {
66 u_long srounds;
67 uint8_t alt_result[32], temp_result[32];
68 SHA256_CTX ctx, alt_ctx;
69 size_t salt_len, key_len, cnt, rounds;
70 char *cp, *p_bytes, *s_bytes, *endp;
71 const char *num;
72 bool rounds_custom;
73
74 /* Default number of rounds. */
75 rounds = ROUNDS_DEFAULT;
76 rounds_custom = false;
77
78 /* Find beginning of salt string. The prefix should normally always
79 * be present. Just in case it is not. */
80 if (strncmp(sha256_salt_prefix, salt, sizeof(sha256_salt_prefix) - 1) == 0)
81 /* Skip salt prefix. */
82 salt += sizeof(sha256_salt_prefix) - 1;
83
84 if (strncmp(salt, sha256_rounds_prefix, sizeof(sha256_rounds_prefix) - 1)
85 == 0) {
86 num = salt + sizeof(sha256_rounds_prefix) - 1;
87 srounds = strtoul(num, &endp, 10);
88
89 if (*endp == '$') {
90 salt = endp + 1;
91 rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX));
92 rounds_custom = true;
93 }
94 }
95
96 salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX);
97 key_len = strlen(key);
98
99 /* Prepare for the real work. */
100 SHA256_Init(&ctx);
101
102 /* Add the key string. */
103 SHA256_Update(&ctx, key, key_len);
104
105 /* The last part is the salt string. This must be at most 8
106 * characters and it ends at the first `$' character (for
107 * compatibility with existing implementations). */
108 SHA256_Update(&ctx, salt, salt_len);
109
110 /* Compute alternate SHA256 sum with input KEY, SALT, and KEY. The
111 * final result will be added to the first context. */
112 SHA256_Init(&alt_ctx);
113
114 /* Add key. */
115 SHA256_Update(&alt_ctx, key, key_len);
116
117 /* Add salt. */
118 SHA256_Update(&alt_ctx, salt, salt_len);
119
120 /* Add key again. */
121 SHA256_Update(&alt_ctx, key, key_len);
122
123 /* Now get result of this (32 bytes) and add it to the other context. */
124 SHA256_Final(alt_result, &alt_ctx);
125
126 /* Add for any character in the key one byte of the alternate sum. */
127 for (cnt = key_len; cnt > 32; cnt -= 32)
128 SHA256_Update(&ctx, alt_result, 32);
129 SHA256_Update(&ctx, alt_result, cnt);
130
131 /* Take the binary representation of the length of the key and for
132 * every 1 add the alternate sum, for every 0 the key. */
133 for (cnt = key_len; cnt > 0; cnt >>= 1)
134 if ((cnt & 1) != 0)
135 SHA256_Update(&ctx, alt_result, 32);
136 else
137 SHA256_Update(&ctx, key, key_len);
138
139 /* Create intermediate result. */
140 SHA256_Final(alt_result, &ctx);
141
142 /* Start computation of P byte sequence. */
143 SHA256_Init(&alt_ctx);
144
145 /* For every character in the password add the entire password. */
146 for (cnt = 0; cnt < key_len; ++cnt)
147 SHA256_Update(&alt_ctx, key, key_len);
148
149 /* Finish the digest. */
150 SHA256_Final(temp_result, &alt_ctx);
151
152 /* Create byte sequence P. */
153 cp = p_bytes = alloca(key_len);
154 for (cnt = key_len; cnt >= 32; cnt -= 32) {
155 memcpy(cp, temp_result, 32);
156 cp += 32;
157 }
158 memcpy(cp, temp_result, cnt);
159
160 /* Start computation of S byte sequence. */
161 SHA256_Init(&alt_ctx);
162
163 /* For every character in the password add the entire password. */
164 for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt)
165 SHA256_Update(&alt_ctx, salt, salt_len);
166
167 /* Finish the digest. */
168 SHA256_Final(temp_result, &alt_ctx);
169
170 /* Create byte sequence S. */
171 cp = s_bytes = alloca(salt_len);
172 for (cnt = salt_len; cnt >= 32; cnt -= 32) {
173 memcpy(cp, temp_result, 32);
174 cp += 32;
175 }
176 memcpy(cp, temp_result, cnt);
177
178 /* Repeatedly run the collected hash value through SHA256 to burn CPU
179 * cycles. */
180 for (cnt = 0; cnt < rounds; ++cnt) {
181 /* New context. */
182 SHA256_Init(&ctx);
183
184 /* Add key or last result. */
185 if ((cnt & 1) != 0)
186 SHA256_Update(&ctx, p_bytes, key_len);
187 else
188 SHA256_Update(&ctx, alt_result, 32);
189
190 /* Add salt for numbers not divisible by 3. */
191 if (cnt % 3 != 0)
192 SHA256_Update(&ctx, s_bytes, salt_len);
193
194 /* Add key for numbers not divisible by 7. */
195 if (cnt % 7 != 0)
196 SHA256_Update(&ctx, p_bytes, key_len);
197
198 /* Add key or last result. */
199 if ((cnt & 1) != 0)
200 SHA256_Update(&ctx, alt_result, 32);
201 else
202 SHA256_Update(&ctx, p_bytes, key_len);
203
204 /* Create intermediate result. */
205 SHA256_Final(alt_result, &ctx);
206 }
207
208 /* Now we can construct the result string. It consists of three
209 * parts. */
210 cp = stpcpy(buffer, sha256_salt_prefix);
211
212 if (rounds_custom)
213 cp += sprintf(cp, "%s%zu$", sha256_rounds_prefix, rounds);
214
215 cp = stpncpy(cp, salt, salt_len);
216
217 *cp++ = '$';
218
219 b64_from_24bit(alt_result[0], alt_result[10], alt_result[20], 4, &cp);
220 b64_from_24bit(alt_result[21], alt_result[1], alt_result[11], 4, &cp);
221 b64_from_24bit(alt_result[12], alt_result[22], alt_result[2], 4, &cp);
222 b64_from_24bit(alt_result[3], alt_result[13], alt_result[23], 4, &cp);
223 b64_from_24bit(alt_result[24], alt_result[4], alt_result[14], 4, &cp);
224 b64_from_24bit(alt_result[15], alt_result[25], alt_result[5], 4, &cp);
225 b64_from_24bit(alt_result[6], alt_result[16], alt_result[26], 4, &cp);
226 b64_from_24bit(alt_result[27], alt_result[7], alt_result[17], 4, &cp);
227 b64_from_24bit(alt_result[18], alt_result[28], alt_result[8], 4, &cp);
228 b64_from_24bit(alt_result[9], alt_result[19], alt_result[29], 4, &cp);
229 b64_from_24bit(0, alt_result[31], alt_result[30], 3, &cp);
230 *cp = '\0'; /* Terminate the string. */
231
232 /* Clear the buffer for the intermediate result so that people
233 * attaching to processes or reading core dumps cannot get any
234 * information. We do it in this way to clear correct_words[] inside
235 * the SHA256 implementation as well. */
236 SHA256_Init(&ctx);
237 SHA256_Final(alt_result, &ctx);
238 explicit_bzero(temp_result, sizeof(temp_result));
239 explicit_bzero(p_bytes, key_len);
240 explicit_bzero(s_bytes, salt_len);
241
242 return (0);
243 }
244
245 #ifdef TEST
246
247 static const struct {
248 const char *input;
249 const char result[32];
250 } tests[] =
251 {
252 /* Test vectors from FIPS 180-2: appendix B.1. */
253 {
254 "abc",
255 "\xba\x78\x16\xbf\x8f\x01\xcf\xea\x41\x41\x40\xde\x5d\xae\x22\x23"
256 "\xb0\x03\x61\xa3\x96\x17\x7a\x9c\xb4\x10\xff\x61\xf2\x00\x15\xad"
257 },
258 /* Test vectors from FIPS 180-2: appendix B.2. */
259 {
260 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
261 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39"
262 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1"
263 },
264 /* Test vectors from the NESSIE project. */
265 {
266 "",
267 "\xe3\xb0\xc4\x42\x98\xfc\x1c\x14\x9a\xfb\xf4\xc8\x99\x6f\xb9\x24"
268 "\x27\xae\x41\xe4\x64\x9b\x93\x4c\xa4\x95\x99\x1b\x78\x52\xb8\x55"
269 },
270 {
271 "a",
272 "\xca\x97\x81\x12\xca\x1b\xbd\xca\xfa\xc2\x31\xb3\x9a\x23\xdc\x4d"
273 "\xa7\x86\xef\xf8\x14\x7c\x4e\x72\xb9\x80\x77\x85\xaf\xee\x48\xbb"
274 },
275 {
276 "message digest",
277 "\xf7\x84\x6f\x55\xcf\x23\xe1\x4e\xeb\xea\xb5\xb4\xe1\x55\x0c\xad"
278 "\x5b\x50\x9e\x33\x48\xfb\xc4\xef\xa3\xa1\x41\x3d\x39\x3c\xb6\x50"
279 },
280 {
281 "abcdefghijklmnopqrstuvwxyz",
282 "\x71\xc4\x80\xdf\x93\xd6\xae\x2f\x1e\xfa\xd1\x44\x7c\x66\xc9\x52"
283 "\x5e\x31\x62\x18\xcf\x51\xfc\x8d\x9e\xd8\x32\xf2\xda\xf1\x8b\x73"
284 },
285 {
286 "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
287 "\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39"
288 "\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1"
289 },
290 {
291 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
292 "\xdb\x4b\xfc\xbd\x4d\xa0\xcd\x85\xa6\x0c\x3c\x37\xd3\xfb\xd8\x80"
293 "\x5c\x77\xf1\x5f\xc6\xb1\xfd\xfe\x61\x4e\xe0\xa7\xc8\xfd\xb4\xc0"
294 },
295 {
296 "123456789012345678901234567890123456789012345678901234567890"
297 "12345678901234567890",
298 "\xf3\x71\xbc\x4a\x31\x1f\x2b\x00\x9e\xef\x95\x2d\xd8\x3c\xa8\x0e"
299 "\x2b\x60\x02\x6c\x8e\x93\x55\x92\xd0\xf9\xc3\x08\x45\x3c\x81\x3e"
300 }
301 };
302
303 #define ntests (sizeof (tests) / sizeof (tests[0]))
304
305 static const struct {
306 const char *salt;
307 const char *input;
308 const char *expected;
309 } tests2[] =
310 {
311 {
312 "$5$saltstring", "Hello world!",
313 "$5$saltstring$5B8vYYiY.CVt1RlTTf8KbXBH3hsxY/GNooZaBBGWEc5"
314 },
315 {
316 "$5$rounds=10000$saltstringsaltstring", "Hello world!",
317 "$5$rounds=10000$saltstringsaltst$3xv.VbSHBb41AL9AvLeujZkZRBAwqFMz2."
318 "opqey6IcA"
319 },
320 {
321 "$5$rounds=5000$toolongsaltstring", "This is just a test",
322 "$5$rounds=5000$toolongsaltstrin$Un/5jzAHMgOGZ5.mWJpuVolil07guHPvOW8"
323 "mGRcvxa5"
324 },
325 {
326 "$5$rounds=1400$anotherlongsaltstring",
327 "a very much longer text to encrypt. This one even stretches over more"
328 "than one line.",
329 "$5$rounds=1400$anotherlongsalts$Rx.j8H.h8HjEDGomFU8bDkXm3XIUnzyxf12"
330 "oP84Bnq1"
331 },
332 {
333 "$5$rounds=77777$short",
334 "we have a short salt string but not a short password",
335 "$5$rounds=77777$short$JiO1O3ZpDAxGJeaDIuqCoEFysAe1mZNJRs3pw0KQRd/"
336 },
337 {
338 "$5$rounds=123456$asaltof16chars..", "a short string",
339 "$5$rounds=123456$asaltof16chars..$gP3VQ/6X7UUEW3HkBn2w1/Ptq2jxPyzV/"
340 "cZKmF/wJvD"
341 },
342 {
343 "$5$rounds=10$roundstoolow", "the minimum number is still observed",
344 "$5$rounds=1000$roundstoolow$yfvwcWrQ8l/K0DAWyuPMDNHpIVlTQebY9l/gL97"
345 "2bIC"
346 },
347 };
348
349 #define ntests2 (sizeof (tests2) / sizeof (tests2[0]))
350
351 int
main(void)352 main(void)
353 {
354 SHA256_CTX ctx;
355 uint8_t sum[32];
356 int result = 0;
357 int i, cnt;
358
359 for (cnt = 0; cnt < (int)ntests; ++cnt) {
360 SHA256_Init(&ctx);
361 SHA256_Update(&ctx, tests[cnt].input, strlen(tests[cnt].input));
362 SHA256_Final(sum, &ctx);
363 if (memcmp(tests[cnt].result, sum, 32) != 0) {
364 for (i = 0; i < 32; i++)
365 printf("%02X", tests[cnt].result[i]);
366 printf("\n");
367 for (i = 0; i < 32; i++)
368 printf("%02X", sum[i]);
369 printf("\n");
370 printf("test %d run %d failed\n", cnt, 1);
371 result = 1;
372 }
373
374 SHA256_Init(&ctx);
375 for (i = 0; tests[cnt].input[i] != '\0'; ++i)
376 SHA256_Update(&ctx, &tests[cnt].input[i], 1);
377 SHA256_Final(sum, &ctx);
378 if (memcmp(tests[cnt].result, sum, 32) != 0) {
379 for (i = 0; i < 32; i++)
380 printf("%02X", tests[cnt].result[i]);
381 printf("\n");
382 for (i = 0; i < 32; i++)
383 printf("%02X", sum[i]);
384 printf("\n");
385 printf("test %d run %d failed\n", cnt, 2);
386 result = 1;
387 }
388 }
389
390 /* Test vector from FIPS 180-2: appendix B.3. */
391 char buf[1000];
392
393 memset(buf, 'a', sizeof(buf));
394 SHA256_Init(&ctx);
395 for (i = 0; i < 1000; ++i)
396 SHA256_Update(&ctx, buf, sizeof(buf));
397 SHA256_Final(sum, &ctx);
398 static const char expected[32] =
399 "\xcd\xc7\x6e\x5c\x99\x14\xfb\x92\x81\xa1\xc7\xe2\x84\xd7\x3e\x67"
400 "\xf1\x80\x9a\x48\xa4\x97\x20\x0e\x04\x6d\x39\xcc\xc7\x11\x2c\xd0";
401
402 if (memcmp(expected, sum, 32) != 0) {
403 printf("test %d failed\n", cnt);
404 result = 1;
405 }
406
407 for (cnt = 0; cnt < ntests2; ++cnt) {
408 char *cp = crypt_sha256(tests2[cnt].input, tests2[cnt].salt);
409
410 if (strcmp(cp, tests2[cnt].expected) != 0) {
411 printf("test %d: expected \"%s\", got \"%s\"\n",
412 cnt, tests2[cnt].expected, cp);
413 result = 1;
414 }
415 }
416
417 if (result == 0)
418 puts("all tests OK");
419
420 return result;
421 }
422
423 #endif /* TEST */
424