1/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
2 * All rights reserved.
3 *
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
7 *
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
14 *
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
21 *
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
24 * are met:
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
39 *
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50 * SUCH DAMAGE.
51 *
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.] */
56
57#include <openssl/bn.h>
58
59#include <assert.h>
60#include <ctype.h>
61#include <limits.h>
62#include <stdio.h>
63
64#include <openssl/bio.h>
65#include <openssl/bytestring.h>
66#include <openssl/err.h>
67#include <openssl/mem.h>
68
69#include "../fipsmodule/bn/internal.h"
70
71
72int BN_bn2cbb_padded(CBB *out, size_t len, const BIGNUM *in) {
73 uint8_t *ptr;
74 return CBB_add_space(out, &ptr, len) && BN_bn2bin_padded(ptr, len, in);
75}
76
77static const char hextable[] = "0123456789abcdef";
78
79char *BN_bn2hex(const BIGNUM *bn) {
80 int width = bn_minimal_width(bn);
81 char *buf = OPENSSL_malloc(1 /* leading '-' */ + 1 /* zero is non-empty */ +
82 width * BN_BYTES * 2 + 1 /* trailing NUL */);
83 if (buf == NULL) {
84 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
85 return NULL;
86 }
87
88 char *p = buf;
89 if (bn->neg) {
90 *(p++) = '-';
91 }
92
93 if (BN_is_zero(bn)) {
94 *(p++) = '0';
95 }
96
97 int z = 0;
98 for (int i = width - 1; i >= 0; i--) {
99 for (int j = BN_BITS2 - 8; j >= 0; j -= 8) {
100 // strip leading zeros
101 int v = ((int)(bn->d[i] >> (long)j)) & 0xff;
102 if (z || v != 0) {
103 *(p++) = hextable[v >> 4];
104 *(p++) = hextable[v & 0x0f];
105 z = 1;
106 }
107 }
108 }
109 *p = '\0';
110
111 return buf;
112}
113
114// decode_hex decodes |in_len| bytes of hex data from |in| and updates |bn|.
115static int decode_hex(BIGNUM *bn, const char *in, int in_len) {
116 if (in_len > INT_MAX/4) {
117 OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);
118 return 0;
119 }
120 // |in_len| is the number of hex digits.
121 if (!bn_expand(bn, in_len * 4)) {
122 return 0;
123 }
124
125 int i = 0;
126 while (in_len > 0) {
127 // Decode one |BN_ULONG| at a time.
128 int todo = BN_BYTES * 2;
129 if (todo > in_len) {
130 todo = in_len;
131 }
132
133 BN_ULONG word = 0;
134 int j;
135 for (j = todo; j > 0; j--) {
136 char c = in[in_len - j];
137
138 BN_ULONG hex;
139 if (c >= '0' && c <= '9') {
140 hex = c - '0';
141 } else if (c >= 'a' && c <= 'f') {
142 hex = c - 'a' + 10;
143 } else if (c >= 'A' && c <= 'F') {
144 hex = c - 'A' + 10;
145 } else {
146 hex = 0;
147 // This shouldn't happen. The caller checks |isxdigit|.
148 assert(0);
149 }
150 word = (word << 4) | hex;
151 }
152
153 bn->d[i++] = word;
154 in_len -= todo;
155 }
156 assert(i <= bn->dmax);
157 bn->width = i;
158 return 1;
159}
160
161// decode_dec decodes |in_len| bytes of decimal data from |in| and updates |bn|.
162static int decode_dec(BIGNUM *bn, const char *in, int in_len) {
163 int i, j;
164 BN_ULONG l = 0;
165
166 // Decode |BN_DEC_NUM| digits at a time.
167 j = BN_DEC_NUM - (in_len % BN_DEC_NUM);
168 if (j == BN_DEC_NUM) {
169 j = 0;
170 }
171 l = 0;
172 for (i = 0; i < in_len; i++) {
173 l *= 10;
174 l += in[i] - '0';
175 if (++j == BN_DEC_NUM) {
176 if (!BN_mul_word(bn, BN_DEC_CONV) ||
177 !BN_add_word(bn, l)) {
178 return 0;
179 }
180 l = 0;
181 j = 0;
182 }
183 }
184 return 1;
185}
186
187typedef int (*decode_func) (BIGNUM *bn, const char *in, int in_len);
188typedef int (*char_test_func) (int c);
189
190static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_func want_char) {
191 BIGNUM *ret = NULL;
192 int neg = 0, i;
193 int num;
194
195 if (in == NULL || *in == 0) {
196 return 0;
197 }
198
199 if (*in == '-') {
200 neg = 1;
201 in++;
202 }
203
204 for (i = 0; want_char((unsigned char)in[i]) && i + neg < INT_MAX; i++) {}
205
206 num = i + neg;
207 if (outp == NULL) {
208 return num;
209 }
210
211 // in is the start of the hex digits, and it is 'i' long
212 if (*outp == NULL) {
213 ret = BN_new();
214 if (ret == NULL) {
215 return 0;
216 }
217 } else {
218 ret = *outp;
219 BN_zero(ret);
220 }
221
222 if (!decode(ret, in, i)) {
223 goto err;
224 }
225
226 bn_set_minimal_width(ret);
227 if (!BN_is_zero(ret)) {
228 ret->neg = neg;
229 }
230
231 *outp = ret;
232 return num;
233
234err:
235 if (*outp == NULL) {
236 BN_free(ret);
237 }
238
239 return 0;
240}
241
242int BN_hex2bn(BIGNUM **outp, const char *in) {
243 return bn_x2bn(outp, in, decode_hex, isxdigit);
244}
245
246char *BN_bn2dec(const BIGNUM *a) {
247 // It is easier to print strings little-endian, so we assemble it in reverse
248 // and fix at the end.
249 BIGNUM *copy = NULL;
250 CBB cbb;
251 if (!CBB_init(&cbb, 16) ||
252 !CBB_add_u8(&cbb, 0 /* trailing NUL */)) {
253 goto cbb_err;
254 }
255
256 if (BN_is_zero(a)) {
257 if (!CBB_add_u8(&cbb, '0')) {
258 goto cbb_err;
259 }
260 } else {
261 copy = BN_dup(a);
262 if (copy == NULL) {
263 goto err;
264 }
265
266 while (!BN_is_zero(copy)) {
267 BN_ULONG word = BN_div_word(copy, BN_DEC_CONV);
268 if (word == (BN_ULONG)-1) {
269 goto err;
270 }
271
272 const int add_leading_zeros = !BN_is_zero(copy);
273 for (int i = 0; i < BN_DEC_NUM && (add_leading_zeros || word != 0); i++) {
274 if (!CBB_add_u8(&cbb, '0' + word % 10)) {
275 goto cbb_err;
276 }
277 word /= 10;
278 }
279 assert(word == 0);
280 }
281 }
282
283 if (BN_is_negative(a) &&
284 !CBB_add_u8(&cbb, '-')) {
285 goto cbb_err;
286 }
287
288 uint8_t *data;
289 size_t len;
290 if (!CBB_finish(&cbb, &data, &len)) {
291 goto cbb_err;
292 }
293
294 // Reverse the buffer.
295 for (size_t i = 0; i < len/2; i++) {
296 uint8_t tmp = data[i];
297 data[i] = data[len - 1 - i];
298 data[len - 1 - i] = tmp;
299 }
300
301 BN_free(copy);
302 return (char *)data;
303
304cbb_err:
305 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
306err:
307 BN_free(copy);
308 CBB_cleanup(&cbb);
309 return NULL;
310}
311
312int BN_dec2bn(BIGNUM **outp, const char *in) {
313 return bn_x2bn(outp, in, decode_dec, isdigit);
314}
315
316int BN_asc2bn(BIGNUM **outp, const char *in) {
317 const char *const orig_in = in;
318 if (*in == '-') {
319 in++;
320 }
321
322 if (in[0] == '0' && (in[1] == 'X' || in[1] == 'x')) {
323 if (!BN_hex2bn(outp, in+2)) {
324 return 0;
325 }
326 } else {
327 if (!BN_dec2bn(outp, in)) {
328 return 0;
329 }
330 }
331
332 if (*orig_in == '-' && !BN_is_zero(*outp)) {
333 (*outp)->neg = 1;
334 }
335
336 return 1;
337}
338
339int BN_print(BIO *bp, const BIGNUM *a) {
340 int i, j, v, z = 0;
341 int ret = 0;
342
343 if (a->neg && BIO_write(bp, "-", 1) != 1) {
344 goto end;
345 }
346
347 if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1) {
348 goto end;
349 }
350
351 for (i = bn_minimal_width(a) - 1; i >= 0; i--) {
352 for (j = BN_BITS2 - 4; j >= 0; j -= 4) {
353 // strip leading zeros
354 v = ((int)(a->d[i] >> (long)j)) & 0x0f;
355 if (z || v != 0) {
356 if (BIO_write(bp, &hextable[v], 1) != 1) {
357 goto end;
358 }
359 z = 1;
360 }
361 }
362 }
363 ret = 1;
364
365end:
366 return ret;
367}
368
369int BN_print_fp(FILE *fp, const BIGNUM *a) {
370 BIO *b = BIO_new_fp(fp, BIO_NOCLOSE);
371 if (b == NULL) {
372 return 0;
373 }
374
375 int ret = BN_print(b, a);
376 BIO_free(b);
377 return ret;
378}
379
380
381size_t BN_bn2mpi(const BIGNUM *in, uint8_t *out) {
382 const size_t bits = BN_num_bits(in);
383 const size_t bytes = (bits + 7) / 8;
384 // If the number of bits is a multiple of 8, i.e. if the MSB is set,
385 // prefix with a zero byte.
386 int extend = 0;
387 if (bytes != 0 && (bits & 0x07) == 0) {
388 extend = 1;
389 }
390
391 const size_t len = bytes + extend;
392 if (len < bytes ||
393 4 + len < len ||
394 (len & 0xffffffff) != len) {
395 // If we cannot represent the number then we emit zero as the interface
396 // doesn't allow an error to be signalled.
397 if (out) {
398 OPENSSL_memset(out, 0, 4);
399 }
400 return 4;
401 }
402
403 if (out == NULL) {
404 return 4 + len;
405 }
406
407 out[0] = len >> 24;
408 out[1] = len >> 16;
409 out[2] = len >> 8;
410 out[3] = len;
411 if (extend) {
412 out[4] = 0;
413 }
414 BN_bn2bin(in, out + 4 + extend);
415 if (in->neg && len > 0) {
416 out[4] |= 0x80;
417 }
418 return len + 4;
419}
420
421BIGNUM *BN_mpi2bn(const uint8_t *in, size_t len, BIGNUM *out) {
422 if (len < 4) {
423 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);
424 return NULL;
425 }
426 const size_t in_len = ((size_t)in[0] << 24) |
427 ((size_t)in[1] << 16) |
428 ((size_t)in[2] << 8) |
429 ((size_t)in[3]);
430 if (in_len != len - 4) {
431 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);
432 return NULL;
433 }
434
435 int out_is_alloced = 0;
436 if (out == NULL) {
437 out = BN_new();
438 if (out == NULL) {
439 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
440 return NULL;
441 }
442 out_is_alloced = 1;
443 }
444
445 if (in_len == 0) {
446 BN_zero(out);
447 return out;
448 }
449
450 in += 4;
451 if (BN_bin2bn(in, in_len, out) == NULL) {
452 if (out_is_alloced) {
453 BN_free(out);
454 }
455 return NULL;
456 }
457 out->neg = ((*in) & 0x80) != 0;
458 if (out->neg) {
459 BN_clear_bit(out, BN_num_bits(out) - 1);
460 }
461 return out;
462}
463
464int BN_bn2binpad(const BIGNUM *in, uint8_t *out, int len) {
465 if (len < 0 ||
466 !BN_bn2bin_padded(out, (size_t)len, in)) {
467 return -1;
468 }
469 return len;
470}
471