1 /*
2 * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include <stdio.h>
11 #include "crypto/ctype.h"
12 #include <limits.h>
13 #include "internal/cryptlib.h"
14 #include <openssl/buffer.h>
15 #include "bn_local.h"
16
17 static const char Hex[] = "0123456789ABCDEF";
18
19 /* Must 'OPENSSL_free' the returned data */
BN_bn2hex(const BIGNUM * a)20 char *BN_bn2hex(const BIGNUM *a)
21 {
22 int i, j, v, z = 0;
23 char *buf;
24 char *p;
25
26 if (BN_is_zero(a))
27 return OPENSSL_strdup("0");
28 buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
29 if (buf == NULL) {
30 BNerr(BN_F_BN_BN2HEX, ERR_R_MALLOC_FAILURE);
31 goto err;
32 }
33 p = buf;
34 if (a->neg)
35 *p++ = '-';
36 for (i = a->top - 1; i >= 0; i--) {
37 for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
38 /* strip leading zeros */
39 v = (int)((a->d[i] >> j) & 0xff);
40 if (z || v != 0) {
41 *p++ = Hex[v >> 4];
42 *p++ = Hex[v & 0x0f];
43 z = 1;
44 }
45 }
46 }
47 *p = '\0';
48 err:
49 return buf;
50 }
51
52 /* Must 'OPENSSL_free' the returned data */
BN_bn2dec(const BIGNUM * a)53 char *BN_bn2dec(const BIGNUM *a)
54 {
55 int i = 0, num, ok = 0, n, tbytes;
56 char *buf = NULL;
57 char *p;
58 BIGNUM *t = NULL;
59 BN_ULONG *bn_data = NULL, *lp;
60 int bn_data_num;
61
62 /*-
63 * get an upper bound for the length of the decimal integer
64 * num <= (BN_num_bits(a) + 1) * log(2)
65 * <= 3 * BN_num_bits(a) * 0.101 + log(2) + 1 (rounding error)
66 * <= 3 * BN_num_bits(a) / 10 + 3 * BN_num_bits / 1000 + 1 + 1
67 */
68 i = BN_num_bits(a) * 3;
69 num = (i / 10 + i / 1000 + 1) + 1;
70 tbytes = num + 3; /* negative and terminator and one spare? */
71 bn_data_num = num / BN_DEC_NUM + 1;
72 bn_data = OPENSSL_malloc(bn_data_num * sizeof(BN_ULONG));
73 buf = OPENSSL_malloc(tbytes);
74 if (buf == NULL || bn_data == NULL) {
75 BNerr(BN_F_BN_BN2DEC, ERR_R_MALLOC_FAILURE);
76 goto err;
77 }
78 if ((t = BN_dup(a)) == NULL)
79 goto err;
80
81 p = buf;
82 lp = bn_data;
83 if (BN_is_zero(t)) {
84 *p++ = '0';
85 *p++ = '\0';
86 } else {
87 if (BN_is_negative(t))
88 *p++ = '-';
89
90 while (!BN_is_zero(t)) {
91 if (lp - bn_data >= bn_data_num)
92 goto err;
93 *lp = BN_div_word(t, BN_DEC_CONV);
94 if (*lp == (BN_ULONG)-1)
95 goto err;
96 lp++;
97 }
98 lp--;
99 /*
100 * We now have a series of blocks, BN_DEC_NUM chars in length, where
101 * the last one needs truncation. The blocks need to be reversed in
102 * order.
103 */
104 n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT1, *lp);
105 if (n < 0)
106 goto err;
107 p += n;
108 while (lp != bn_data) {
109 lp--;
110 n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT2, *lp);
111 if (n < 0)
112 goto err;
113 p += n;
114 }
115 }
116 ok = 1;
117 err:
118 OPENSSL_free(bn_data);
119 BN_free(t);
120 if (ok)
121 return buf;
122 OPENSSL_free(buf);
123 return NULL;
124 }
125
BN_hex2bn(BIGNUM ** bn,const char * a)126 int BN_hex2bn(BIGNUM **bn, const char *a)
127 {
128 BIGNUM *ret = NULL;
129 BN_ULONG l = 0;
130 int neg = 0, h, m, i, j, k, c;
131 int num;
132
133 if (a == NULL || *a == '\0')
134 return 0;
135
136 if (*a == '-') {
137 neg = 1;
138 a++;
139 }
140
141 for (i = 0; i <= INT_MAX / 4 && ossl_isxdigit(a[i]); i++)
142 continue;
143
144 if (i == 0 || i > INT_MAX / 4)
145 return 0;
146
147 num = i + neg;
148 if (bn == NULL)
149 return num;
150
151 /* a is the start of the hex digits, and it is 'i' long */
152 if (*bn == NULL) {
153 if ((ret = BN_new()) == NULL)
154 return 0;
155 } else {
156 ret = *bn;
157 BN_zero(ret);
158 }
159
160 /* i is the number of hex digits */
161 if (bn_expand(ret, i * 4) == NULL)
162 goto err;
163
164 j = i; /* least significant 'hex' */
165 m = 0;
166 h = 0;
167 while (j > 0) {
168 m = (BN_BYTES * 2 <= j) ? BN_BYTES * 2 : j;
169 l = 0;
170 for (;;) {
171 c = a[j - m];
172 k = OPENSSL_hexchar2int(c);
173 if (k < 0)
174 k = 0; /* paranoia */
175 l = (l << 4) | k;
176
177 if (--m <= 0) {
178 ret->d[h++] = l;
179 break;
180 }
181 }
182 j -= BN_BYTES * 2;
183 }
184 ret->top = h;
185 bn_correct_top(ret);
186
187 *bn = ret;
188 bn_check_top(ret);
189 /* Don't set the negative flag if it's zero. */
190 if (ret->top != 0)
191 ret->neg = neg;
192 return num;
193 err:
194 if (*bn == NULL)
195 BN_free(ret);
196 return 0;
197 }
198
BN_dec2bn(BIGNUM ** bn,const char * a)199 int BN_dec2bn(BIGNUM **bn, const char *a)
200 {
201 BIGNUM *ret = NULL;
202 BN_ULONG l = 0;
203 int neg = 0, i, j;
204 int num;
205
206 if (a == NULL || *a == '\0')
207 return 0;
208 if (*a == '-') {
209 neg = 1;
210 a++;
211 }
212
213 for (i = 0; i <= INT_MAX / 4 && ossl_isdigit(a[i]); i++)
214 continue;
215
216 if (i == 0 || i > INT_MAX / 4)
217 goto err;
218
219 num = i + neg;
220 if (bn == NULL)
221 return num;
222
223 /*
224 * a is the start of the digits, and it is 'i' long. We chop it into
225 * BN_DEC_NUM digits at a time
226 */
227 if (*bn == NULL) {
228 if ((ret = BN_new()) == NULL)
229 return 0;
230 } else {
231 ret = *bn;
232 BN_zero(ret);
233 }
234
235 /* i is the number of digits, a bit of an over expand */
236 if (bn_expand(ret, i * 4) == NULL)
237 goto err;
238
239 j = BN_DEC_NUM - i % BN_DEC_NUM;
240 if (j == BN_DEC_NUM)
241 j = 0;
242 l = 0;
243 while (--i >= 0) {
244 l *= 10;
245 l += *a - '0';
246 a++;
247 if (++j == BN_DEC_NUM) {
248 if (!BN_mul_word(ret, BN_DEC_CONV)
249 || !BN_add_word(ret, l))
250 goto err;
251 l = 0;
252 j = 0;
253 }
254 }
255
256 bn_correct_top(ret);
257 *bn = ret;
258 bn_check_top(ret);
259 /* Don't set the negative flag if it's zero. */
260 if (ret->top != 0)
261 ret->neg = neg;
262 return num;
263 err:
264 if (*bn == NULL)
265 BN_free(ret);
266 return 0;
267 }
268
BN_asc2bn(BIGNUM ** bn,const char * a)269 int BN_asc2bn(BIGNUM **bn, const char *a)
270 {
271 const char *p = a;
272
273 if (*p == '-')
274 p++;
275
276 if (p[0] == '0' && (p[1] == 'X' || p[1] == 'x')) {
277 if (!BN_hex2bn(bn, p + 2))
278 return 0;
279 } else {
280 if (!BN_dec2bn(bn, p))
281 return 0;
282 }
283 /* Don't set the negative flag if it's zero. */
284 if (*a == '-' && (*bn)->top != 0)
285 (*bn)->neg = 1;
286 return 1;
287 }
288
289 # ifndef OPENSSL_NO_STDIO
BN_print_fp(FILE * fp,const BIGNUM * a)290 int BN_print_fp(FILE *fp, const BIGNUM *a)
291 {
292 BIO *b;
293 int ret;
294
295 if ((b = BIO_new(BIO_s_file())) == NULL)
296 return 0;
297 BIO_set_fp(b, fp, BIO_NOCLOSE);
298 ret = BN_print(b, a);
299 BIO_free(b);
300 return ret;
301 }
302 # endif
303
BN_print(BIO * bp,const BIGNUM * a)304 int BN_print(BIO *bp, const BIGNUM *a)
305 {
306 int i, j, v, z = 0;
307 int ret = 0;
308
309 if ((a->neg) && BIO_write(bp, "-", 1) != 1)
310 goto end;
311 if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1)
312 goto end;
313 for (i = a->top - 1; i >= 0; i--) {
314 for (j = BN_BITS2 - 4; j >= 0; j -= 4) {
315 /* strip leading zeros */
316 v = (int)((a->d[i] >> j) & 0x0f);
317 if (z || v != 0) {
318 if (BIO_write(bp, &Hex[v], 1) != 1)
319 goto end;
320 z = 1;
321 }
322 }
323 }
324 ret = 1;
325 end:
326 return ret;
327 }
328
BN_options(void)329 char *BN_options(void)
330 {
331 static int init = 0;
332 static char data[16];
333
334 if (!init) {
335 init++;
336 #ifdef BN_LLONG
337 BIO_snprintf(data, sizeof(data), "bn(%zu,%zu)",
338 sizeof(BN_ULLONG) * 8, sizeof(BN_ULONG) * 8);
339 #else
340 BIO_snprintf(data, sizeof(data), "bn(%zu,%zu)",
341 sizeof(BN_ULONG) * 8, sizeof(BN_ULONG) * 8);
342 #endif
343 }
344 return data;
345 }
346