1 /*
2 * Copyright 1995-2024 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (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 <openssl/err.h>
11 #include "crypto/ctype.h"
12 #include "bn_local.h"
13
14 /* Must 'OPENSSL_free' the returned data */
BN_bn2hex(const BIGNUM * a)15 char *BN_bn2hex(const BIGNUM *a)
16 {
17 int i, j, v, z = 0;
18 char *buf;
19 char *p;
20
21 if (BN_is_zero(a))
22 return OPENSSL_strdup("0");
23 buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
24 if (buf == NULL)
25 goto err;
26 p = buf;
27 if (a->neg)
28 *p++ = '-';
29 for (i = a->top - 1; i >= 0; i--) {
30 for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
31 /* strip leading zeros */
32 v = (int)((a->d[i] >> j) & 0xff);
33 if (z || v != 0) {
34 p += ossl_to_hex(p, v);
35 z = 1;
36 }
37 }
38 }
39 *p = '\0';
40 err:
41 return buf;
42 }
43
44 #ifndef FIPS_MODULE
45 /* No BIO_snprintf in FIPS_MODULE */
46 /* Must 'OPENSSL_free' the returned data */
BN_bn2dec(const BIGNUM * a)47 char *BN_bn2dec(const BIGNUM *a)
48 {
49 int i = 0, num, ok = 0, n, tbytes;
50 char *buf = NULL;
51 char *p;
52 BIGNUM *t = NULL;
53 BN_ULONG *bn_data = NULL, *lp;
54 int bn_data_num;
55
56 /*-
57 * get an upper bound for the length of the decimal integer
58 * num <= (BN_num_bits(a) + 1) * log(2)
59 * <= 3 * BN_num_bits(a) * 0.101 + log(2) + 1 (rounding error)
60 * <= 3 * BN_num_bits(a) / 10 + 3 * BN_num_bits / 1000 + 1 + 1
61 */
62 i = BN_num_bits(a) * 3;
63 num = (i / 10 + i / 1000 + 1) + 1;
64 tbytes = num + 3; /* negative and terminator and one spare? */
65 bn_data_num = num / BN_DEC_NUM + 1;
66 bn_data = OPENSSL_malloc(bn_data_num * sizeof(BN_ULONG));
67 buf = OPENSSL_malloc(tbytes);
68 if (buf == NULL || bn_data == NULL)
69 goto err;
70 if ((t = BN_dup(a)) == NULL)
71 goto err;
72
73 p = buf;
74 lp = bn_data;
75 if (BN_is_zero(t)) {
76 *p++ = '0';
77 *p++ = '\0';
78 } else {
79 if (BN_is_negative(t))
80 *p++ = '-';
81
82 while (!BN_is_zero(t)) {
83 if (lp - bn_data >= bn_data_num)
84 goto err;
85 *lp = BN_div_word(t, BN_DEC_CONV);
86 if (*lp == (BN_ULONG)-1)
87 goto err;
88 lp++;
89 }
90 lp--;
91 /*
92 * We now have a series of blocks, BN_DEC_NUM chars in length, where
93 * the last one needs truncation. The blocks need to be reversed in
94 * order.
95 */
96 n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT1, *lp);
97 if (n < 0)
98 goto err;
99 p += n;
100 while (lp != bn_data) {
101 lp--;
102 n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT2, *lp);
103 if (n < 0)
104 goto err;
105 p += n;
106 }
107 }
108 ok = 1;
109 err:
110 OPENSSL_free(bn_data);
111 BN_free(t);
112 if (ok)
113 return buf;
114 OPENSSL_free(buf);
115 return NULL;
116 }
117 #endif
118
BN_hex2bn(BIGNUM ** bn,const char * a)119 int BN_hex2bn(BIGNUM **bn, const char *a)
120 {
121 BIGNUM *ret = NULL;
122 BN_ULONG l = 0;
123 int neg = 0, h, m, i, j, k, c;
124 int num;
125
126 if (a == NULL || *a == '\0')
127 return 0;
128
129 if (*a == '-') {
130 neg = 1;
131 a++;
132 }
133
134 for (i = 0; i <= INT_MAX / 4 && ossl_isxdigit(a[i]); i++)
135 continue;
136
137 if (i == 0 || i > INT_MAX / 4)
138 return 0;
139
140 num = i + neg;
141 if (bn == NULL)
142 return num;
143
144 /* a is the start of the hex digits, and it is 'i' long */
145 if (*bn == NULL) {
146 if ((ret = BN_new()) == NULL)
147 return 0;
148 } else {
149 ret = *bn;
150 if (BN_get_flags(ret, BN_FLG_STATIC_DATA)) {
151 ERR_raise(ERR_LIB_BN, ERR_R_PASSED_INVALID_ARGUMENT);
152 return 0;
153 }
154 BN_zero(ret);
155 }
156
157 /* i is the number of hex digits */
158 if (bn_expand(ret, i * 4) == NULL)
159 goto err;
160
161 j = i; /* least significant 'hex' */
162 m = 0;
163 h = 0;
164 while (j > 0) {
165 m = (BN_BYTES * 2 <= j) ? BN_BYTES * 2 : j;
166 l = 0;
167 for (;;) {
168 c = a[j - m];
169 k = OPENSSL_hexchar2int(c);
170 if (k < 0)
171 k = 0; /* paranoia */
172 l = (l << 4) | k;
173
174 if (--m <= 0) {
175 ret->d[h++] = l;
176 break;
177 }
178 }
179 j -= BN_BYTES * 2;
180 }
181 ret->top = h;
182 bn_correct_top(ret);
183
184 *bn = ret;
185 bn_check_top(ret);
186 /* Don't set the negative flag if it's zero. */
187 if (ret->top != 0)
188 ret->neg = neg;
189 return num;
190 err:
191 if (*bn == NULL)
192 BN_free(ret);
193 return 0;
194 }
195
BN_dec2bn(BIGNUM ** bn,const char * a)196 int BN_dec2bn(BIGNUM **bn, const char *a)
197 {
198 BIGNUM *ret = NULL;
199 BN_ULONG l = 0;
200 int neg = 0, i, j;
201 int num;
202
203 if (a == NULL || *a == '\0')
204 return 0;
205 if (*a == '-') {
206 neg = 1;
207 a++;
208 }
209
210 for (i = 0; i <= INT_MAX / 4 && ossl_isdigit(a[i]); i++)
211 continue;
212
213 if (i == 0 || i > INT_MAX / 4)
214 goto err;
215
216 num = i + neg;
217 if (bn == NULL)
218 return num;
219
220 /*
221 * a is the start of the digits, and it is 'i' long. We chop it into
222 * BN_DEC_NUM digits at a time
223 */
224 if (*bn == NULL) {
225 if ((ret = BN_new()) == NULL)
226 return 0;
227 } else {
228 ret = *bn;
229 BN_zero(ret);
230 }
231
232 /* i is the number of digits, a bit of an over expand */
233 if (bn_expand(ret, i * 4) == NULL)
234 goto err;
235
236 j = BN_DEC_NUM - i % BN_DEC_NUM;
237 if (j == BN_DEC_NUM)
238 j = 0;
239 l = 0;
240 while (--i >= 0) {
241 l *= 10;
242 l += *a - '0';
243 a++;
244 if (++j == BN_DEC_NUM) {
245 if (!BN_mul_word(ret, BN_DEC_CONV)
246 || !BN_add_word(ret, l))
247 goto err;
248 l = 0;
249 j = 0;
250 }
251 }
252
253 bn_correct_top(ret);
254 *bn = ret;
255 bn_check_top(ret);
256 /* Don't set the negative flag if it's zero. */
257 if (ret->top != 0)
258 ret->neg = neg;
259 return num;
260 err:
261 if (*bn == NULL)
262 BN_free(ret);
263 return 0;
264 }
265
BN_asc2bn(BIGNUM ** bn,const char * a)266 int BN_asc2bn(BIGNUM **bn, const char *a)
267 {
268 const char *p = a;
269
270 if (*p == '-')
271 p++;
272
273 if (p[0] == '0' && (p[1] == 'X' || p[1] == 'x')) {
274 if (!BN_hex2bn(bn, p + 2))
275 return 0;
276 } else {
277 if (!BN_dec2bn(bn, p))
278 return 0;
279 }
280 /* Don't set the negative flag if it's zero. */
281 if (*a == '-' && (*bn)->top != 0)
282 (*bn)->neg = 1;
283 return 1;
284 }
285
