1/*
2 * Copyright 1995-2017 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
14static const char Hex[] = "0123456789ABCDEF";
15
16/* Must 'OPENSSL_free' the returned data */
17char *BN_bn2hex(const BIGNUM *a)
18{
19 int i, j, v, z = 0;
20 char *buf;
21 char *p;
22
23 if (BN_is_zero(a))
24 return OPENSSL_strdup("0");
25 buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
26 if (buf == NULL) {
27 BNerr(BN_F_BN_BN2HEX, ERR_R_MALLOC_FAILURE);
28 goto err;
29 }
30 p = buf;
31 if (a->neg)
32 *p++ = '-';
33 for (i = a->top - 1; i >= 0; i--) {
34 for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
35 /* strip leading zeros */
36 v = (int)((a->d[i] >> j) & 0xff);
37 if (z || v != 0) {
38 *p++ = Hex[v >> 4];
39 *p++ = Hex[v & 0x0f];
40 z = 1;
41 }
42 }
43 }
44 *p = '\0';
45 err:
46 return buf;
47}
48
49#ifndef FIPS_MODE
50/* No BIO_snprintf in FIPS_MODE */
51/* Must 'OPENSSL_free' the returned data */
52char *BN_bn2dec(const BIGNUM *a)
53{
54 int i = 0, num, ok = 0, n, tbytes;
55 char *buf = NULL;
56 char *p;
57 BIGNUM *t = NULL;
58 BN_ULONG *bn_data = NULL, *lp;
59 int bn_data_num;
60
61 /*-
62 * get an upper bound for the length of the decimal integer
63 * num <= (BN_num_bits(a) + 1) * log(2)
64 * <= 3 * BN_num_bits(a) * 0.101 + log(2) + 1 (rounding error)
65 * <= 3 * BN_num_bits(a) / 10 + 3 * BN_num_bits / 1000 + 1 + 1
66 */
67 i = BN_num_bits(a) * 3;
68 num = (i / 10 + i / 1000 + 1) + 1;
69 tbytes = num + 3; /* negative and terminator and one spare? */
70 bn_data_num = num / BN_DEC_NUM + 1;
71 bn_data = OPENSSL_malloc(bn_data_num * sizeof(BN_ULONG));
72 buf = OPENSSL_malloc(tbytes);
73 if (buf == NULL || bn_data == NULL) {
74 BNerr(BN_F_BN_BN2DEC, ERR_R_MALLOC_FAILURE);
75 goto err;
76 }
77 if ((t = BN_dup(a)) == NULL)
78 goto err;
79
80 p = buf;
81 lp = bn_data;
82 if (BN_is_zero(t)) {
83 *p++ = '0';
84 *p++ = '\0';
85 } else {
86 if (BN_is_negative(t))
87 *p++ = '-';
88
89 while (!BN_is_zero(t)) {
90 if (lp - bn_data >= bn_data_num)
91 goto err;
92 *lp = BN_div_word(t, BN_DEC_CONV);
93 if (*lp == (BN_ULONG)-1)
94 goto err;
95 lp++;
96 }
97 lp--;
98 /*
99 * We now have a series of blocks, BN_DEC_NUM chars in length, where
100 * the last one needs truncation. The blocks need to be reversed in
101 * order.
102 */
103 n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT1, *lp);
104 if (n < 0)
105 goto err;
106 p += n;
107 while (lp != bn_data) {
108 lp--;
109 n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT2, *lp);
110 if (n < 0)
111 goto err;
112 p += n;
113 }
114 }
115 ok = 1;
116 err:
117 OPENSSL_free(bn_data);
118 BN_free(t);
119 if (ok)
120 return buf;
121 OPENSSL_free(buf);
122 return NULL;
123}
124#endif
125
126int 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 goto err;
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
199int 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
269int 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