/src/openssl/crypto/bn/bn_conv.c

Source
/*
 * Copyright 1995-2025 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdio.h>

#include <openssl/err.h>
#include "crypto/ctype.h"
#include "bn_local.h"

/* Must 'OPENSSL_free' the returned data */
char *BN_bn2hex(const BIGNUM *a)
{
    int i, j, v, z = 0;
    char *buf;
    char *p;

    if (BN_is_zero(a))
        return OPENSSL_strdup("0");
    buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
    if (buf == NULL)
        goto err;
    p = buf;
    if (a->neg)
        *p++ = '-';
    for (i = a->top - 1; i >= 0; i--) {
        for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
            /* strip leading zeros */
            v = (int)((a->d[i] >> j) & 0xff);
            if (z || v != 0) {
                p += ossl_to_hex(p, v);
                z = 1;
            }
        }
    }
    *p = '\0';
err:
    return buf;
}

#ifndef FIPS_MODULE
/* No BIO_snprintf in FIPS_MODULE */
/* Must 'OPENSSL_free' the returned data */
char *BN_bn2dec(const BIGNUM *a)
{
    int i = 0, num, ok = 0, n, tbytes;
    char *buf = NULL;
    char *p;
    BIGNUM *t = NULL;
    BN_ULONG *bn_data = NULL, *lp;
    int bn_data_num;

    /*-
     * get an upper bound for the length of the decimal integer
     * num <= (BN_num_bits(a) + 1) * log(2)
     *     <= 3 * BN_num_bits(a) * 0.101 + log(2) + 1     (rounding error)
     *     <= 3 * BN_num_bits(a) / 10 + 3 * BN_num_bits / 1000 + 1 + 1
     */
    i = BN_num_bits(a) * 3;
    num = (i / 10 + i / 1000 + 1) + 1;
    tbytes = num + 3; /* negative and terminator and one spare? */
    bn_data_num = num / BN_DEC_NUM + 1;
    bn_data = OPENSSL_malloc_array(bn_data_num, sizeof(BN_ULONG));
    buf = OPENSSL_malloc(tbytes);
    if (buf == NULL || bn_data == NULL)
        goto err;
    if ((t = BN_dup(a)) == NULL)
        goto err;

    p = buf;
    lp = bn_data;
    if (BN_is_zero(t)) {
        *p++ = '0';
        *p++ = '\0';
    } else {
        if (BN_is_negative(t))
            *p++ = '-';

        while (!BN_is_zero(t)) {
            if (lp - bn_data >= bn_data_num)
                goto err;
            *lp = BN_div_word(t, BN_DEC_CONV);
            if (*lp == (BN_ULONG)-1)
                goto err;
            lp++;
        }
        lp--;
        /*
         * We now have a series of blocks, BN_DEC_NUM chars in length, where
         * the last one needs truncation. The blocks need to be reversed in
         * order.
         */
        n = snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT1, *lp);
        if (n < 0 || (size_t)n >= tbytes - (size_t)(p - buf))
            goto err;
        p += n;
        while (lp != bn_data) {
            lp--;
            n = snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT2, *lp);
            if (n < 0 || (size_t)n >= tbytes - (size_t)(p - buf))
                goto err;
            p += n;
        }
    }
    ok = 1;
err:
    OPENSSL_free(bn_data);
    BN_free(t);
    if (ok)
        return buf;
    OPENSSL_free(buf);
    return NULL;
}
#endif

int BN_hex2bn(BIGNUM **bn, const char *a)
{
    BIGNUM *ret = NULL;
    BN_ULONG l = 0;
    int neg = 0, h, m, i, j, k, c;
    int num;

    if (a == NULL || *a == '\0')
        return 0;

    if (*a == '-') {
        neg = 1;
        a++;
    }

    for (i = 0; i <= INT_MAX / 4 && ossl_isxdigit(a[i]); i++)
        continue;

    if (i == 0 || i > INT_MAX / 4)
        return 0;

    num = i + neg;
    if (bn == NULL)
        return num;

    /* a is the start of the hex digits, and it is 'i' long */
    if (*bn == NULL) {
        if ((ret = BN_new()) == NULL)
            return 0;
    } else {
        ret = *bn;
        if (BN_get_flags(ret, BN_FLG_STATIC_DATA)) {
            ERR_raise(ERR_LIB_BN, ERR_R_PASSED_INVALID_ARGUMENT);
            return 0;
        }
        BN_zero(ret);
    }

    /* i is the number of hex digits */
    if (bn_expand(ret, i * 4) == NULL)
        goto err;

    j = i; /* least significant 'hex' */
    m = 0;
    h = 0;
    while (j > 0) {
        m = (BN_BYTES * 2 <= j) ? BN_BYTES * 2 : j;
        l = 0;
        for (;;) {
            c = a[j - m];
            k = OPENSSL_hexchar2int(c);
            if (k < 0)
                k = 0; /* paranoia */
            l = (l << 4) | k;

            if (--m <= 0) {
                ret->d[h++] = l;
                break;
            }
        }
        j -= BN_BYTES * 2;
    }
    ret->top = h;
    bn_correct_top(ret);

    *bn = ret;
    bn_check_top(ret);
    /* Don't set the negative flag if it's zero. */
    if (ret->top != 0)
        ret->neg = neg;
    return num;
err:
    if (*bn == NULL)
        BN_free(ret);
    return 0;
}

int BN_dec2bn(BIGNUM **bn, const char *a)
{
    BIGNUM *ret = NULL;
    BN_ULONG l = 0;
    int neg = 0, i, j;
    int num;

    if (a == NULL || *a == '\0')
        return 0;
    if (*a == '-') {
        neg = 1;
        a++;
    }

    for (i = 0; i <= INT_MAX / 4 && ossl_isdigit(a[i]); i++)
        continue;

    if (i == 0 || i > INT_MAX / 4)
        goto err;

    num = i + neg;
    if (bn == NULL)
        return num;

    /*
     * a is the start of the digits, and it is 'i' long. We chop it into
     * BN_DEC_NUM digits at a time
     */
    if (*bn == NULL) {
        if ((ret = BN_new()) == NULL)
            return 0;
    } else {
        ret = *bn;
        BN_zero(ret);
    }

    /* i is the number of digits, a bit of an over expand */
    if (bn_expand(ret, i * 4) == NULL)
        goto err;

    j = BN_DEC_NUM - i % BN_DEC_NUM;
    if (j == BN_DEC_NUM)
        j = 0;
    l = 0;
    while (--i >= 0) {
        l *= 10;
        l += *a - '0';
        a++;
        if (++j == BN_DEC_NUM) {
            if (!BN_mul_word(ret, BN_DEC_CONV)
                || !BN_add_word(ret, l))
                goto err;
            l = 0;
            j = 0;
        }
    }

    bn_correct_top(ret);
    *bn = ret;
    bn_check_top(ret);
    /* Don't set the negative flag if it's zero. */
    if (ret->top != 0)
        ret->neg = neg;
    return num;
err:
    if (*bn == NULL)
        BN_free(ret);
    return 0;
}

int BN_asc2bn(BIGNUM **bn, const char *a)
{
    const char *p = a;

    if (*p == '-')
        p++;

    if (p[0] == '0' && (p[1] == 'X' || p[1] == 'x')) {
        if (!BN_hex2bn(bn, p + 2))
            return 0;
    } else {
        if (!BN_dec2bn(bn, p))
            return 0;
    }
    /* Don't set the negative flag if it's zero. */
    if (*a == '-' && (*bn)->top != 0)
        (*bn)->neg = 1;
    return 1;
}

Coverage Report

Created: 2026-08-31 06:56

Line	Count	Source
1		/*
2		* Copyright 1995-2025 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 <stdio.h>
11
12		#include <openssl/err.h>
13		#include "crypto/ctype.h"
14		#include "bn_local.h"
15
16		/* Must 'OPENSSL_free' the returned data */
17		char BN_bn2hex(const BIGNUM a)
18	0	{
19	0	int i, j, v, z = 0;
20	0	char *buf;
21	0	char *p;
22
23	0	if (BN_is_zero(a))
24	0	return OPENSSL_strdup("0");
25	0	buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
26	0	if (buf == NULL)
27	0	goto err;
28	0	p = buf;
29	0	if (a->neg)
30	0	*p++ = '-';
31	0	for (i = a->top - 1; i >= 0; i--) {
32	0	for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
33		/* strip leading zeros */
34	0	v = (int)((a->d[i] >> j) & 0xff);
35	0	if (z \|\| v != 0) {
36	0	p += ossl_to_hex(p, v);
37	0	z = 1;
38	0	}
39	0	}
40	0	}
41	0	*p = '\0';
42	0	err:
43	0	return buf;
44	0	}
45
46		#ifndef FIPS_MODULE
47		/* No BIO_snprintf in FIPS_MODULE */
48		/* Must 'OPENSSL_free' the returned data */
49		char BN_bn2dec(const BIGNUM a)
50	0	{
51	0	int i = 0, num, ok = 0, n, tbytes;
52	0	char *buf = NULL;
53	0	char *p;
54	0	BIGNUM *t = NULL;
55	0	BN_ULONG bn_data = NULL, lp;
56	0	int bn_data_num;
57
58		/*-
59		* get an upper bound for the length of the decimal integer
60		* num <= (BN_num_bits(a) + 1) * log(2)
61		* <= 3 * BN_num_bits(a) * 0.101 + log(2) + 1 (rounding error)
62		* <= 3 * BN_num_bits(a) / 10 + 3 * BN_num_bits / 1000 + 1 + 1
63		*/
64	0	i = BN_num_bits(a) * 3;
65	0	num = (i / 10 + i / 1000 + 1) + 1;
66	0	tbytes = num + 3; /* negative and terminator and one spare? */
67	0	bn_data_num = num / BN_DEC_NUM + 1;
68	0	bn_data = OPENSSL_malloc_array(bn_data_num, sizeof(BN_ULONG));
69	0	buf = OPENSSL_malloc(tbytes);
70	0	if (buf == NULL \|\| bn_data == NULL)
71	0	goto err;
72	0	if ((t = BN_dup(a)) == NULL)
73	0	goto err;
74
75	0	p = buf;
76	0	lp = bn_data;
77	0	if (BN_is_zero(t)) {
78	0	*p++ = '0';
79	0	*p++ = '\0';
80	0	} else {
81	0	if (BN_is_negative(t))
82	0	*p++ = '-';
83
84	0	while (!BN_is_zero(t)) {
85	0	if (lp - bn_data >= bn_data_num)
86	0	goto err;
87	0	*lp = BN_div_word(t, BN_DEC_CONV);
88	0	if (*lp == (BN_ULONG)-1)
89	0	goto err;
90	0	lp++;
91	0	}
92	0	lp--;
93		/*
94		* We now have a series of blocks, BN_DEC_NUM chars in length, where
95		* the last one needs truncation. The blocks need to be reversed in
96		* order.
97		*/
98	0	n = snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT1, *lp);
99	0	if (n < 0 \|\| (size_t)n >= tbytes - (size_t)(p - buf))
100	0	goto err;
101	0	p += n;
102	0	while (lp != bn_data) {
103	0	lp--;
104	0	n = snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT2, *lp);
105	0	if (n < 0 \|\| (size_t)n >= tbytes - (size_t)(p - buf))
106	0	goto err;
107	0	p += n;
108	0	}
109	0	}
110	0	ok = 1;
111	0	err:
112	0	OPENSSL_free(bn_data);
113	0	BN_free(t);
114	0	if (ok)
115	0	return buf;
116	0	OPENSSL_free(buf);
117	0	return NULL;
118	0	}
119		#endif
120
121		int BN_hex2bn(BIGNUM *bn, const char a)
122	32	{
123	32	BIGNUM *ret = NULL;
124	32	BN_ULONG l = 0;
125	32	int neg = 0, h, m, i, j, k, c;
126	32	int num;
127
128	32	if (a == NULL \|\| *a == '\0')
129	0	return 0;
130
131	32	if (*a == '-') {
132	0	neg = 1;
133	0	a++;
134	0	}
135
136	12.3k	for (i = 0; i <= INT_MAX / 4 && ossl_isxdigit(a[i]); i++)
137	12.2k	continue;
138
139	32	if (i == 0 \|\| i > INT_MAX / 4)
140	0	return 0;
141
142	32	num = i + neg;
143	32	if (bn == NULL)
144	0	return num;
145
146		/* a is the start of the hex digits, and it is 'i' long */
147	32	if (*bn == NULL) {
148	0	if ((ret = BN_new()) == NULL)
149	0	return 0;
150	32	} else {
151	32	ret = *bn;
152	32	if (BN_get_flags(ret, BN_FLG_STATIC_DATA)) {
153	0	ERR_raise(ERR_LIB_BN, ERR_R_PASSED_INVALID_ARGUMENT);
154	0	return 0;
155	0	}
156	32	BN_zero(ret);
157	32	}
158
159		/* i is the number of hex digits */
160	32	if (bn_expand(ret, i * 4) == NULL)
161	0	goto err;
162
163	32	j = i; /* least significant 'hex' */
164	32	m = 0;
165	32	h = 0;
166	800	while (j > 0) {
167	768	m = (BN_BYTES * 2 <= j) ? BN_BYTES * 2 : j;
168	768	l = 0;
169	12.2k	for (;;) {
170	12.2k	c = a[j - m];
171	12.2k	k = OPENSSL_hexchar2int(c);
172	12.2k	if (k < 0)
173	0	k = 0; /* paranoia */
174	12.2k	l = (l << 4) \| k;
175
176	12.2k	if (--m <= 0) {
177	768	ret->d[h++] = l;
178	768	break;
179	768	}
180	12.2k	}
181	768	j -= BN_BYTES * 2;
182	768	}
183	32	ret->top = h;
184	32	bn_correct_top(ret);
185
186	32	*bn = ret;
187	32	bn_check_top(ret);
188		/* Don't set the negative flag if it's zero. */
189	32	if (ret->top != 0)
190	32	ret->neg = neg;
191	32	return num;
192	0	err:
193	0	if (*bn == NULL)
194	0	BN_free(ret);
195	0	return 0;
196	32	}
197
198		int BN_dec2bn(BIGNUM *bn, const char a)
199	0	{
200	0	BIGNUM *ret = NULL;
201	0	BN_ULONG l = 0;
202	0	int neg = 0, i, j;
203	0	int num;
204
205	0	if (a == NULL \|\| *a == '\0')
206	0	return 0;
207	0	if (*a == '-') {
208	0	neg = 1;
209	0	a++;
210	0	}
211
212	0	for (i = 0; i <= INT_MAX / 4 && ossl_isdigit(a[i]); i++)
213	0	continue;
214
215	0	if (i == 0 \|\| i > INT_MAX / 4)
216	0	goto err;
217
218	0	num = i + neg;
219	0	if (bn == NULL)
220	0	return num;
221
222		/*
223		* a is the start of the digits, and it is 'i' long. We chop it into
224		* BN_DEC_NUM digits at a time
225		*/
226	0	if (*bn == NULL) {
227	0	if ((ret = BN_new()) == NULL)
228	0	return 0;
229	0	} else {
230	0	ret = *bn;
231	0	BN_zero(ret);
232	0	}
233
234		/* i is the number of digits, a bit of an over expand */
235	0	if (bn_expand(ret, i * 4) == NULL)
236	0	goto err;
237
238	0	j = BN_DEC_NUM - i % BN_DEC_NUM;
239	0	if (j == BN_DEC_NUM)
240	0	j = 0;
241	0	l = 0;
242	0	while (--i >= 0) {
243	0	l *= 10;
244	0	l += *a - '0';
245	0	a++;
246	0	if (++j == BN_DEC_NUM) {
247	0	if (!BN_mul_word(ret, BN_DEC_CONV)
248	0	\|\| !BN_add_word(ret, l))
249	0	goto err;
250	0	l = 0;
251	0	j = 0;
252	0	}
253	0	}
254
255	0	bn_correct_top(ret);
256	0	*bn = ret;
257	0	bn_check_top(ret);
258		/* Don't set the negative flag if it's zero. */
259	0	if (ret->top != 0)
260	0	ret->neg = neg;
261	0	return num;
262	0	err:
263	0	if (*bn == NULL)
264	0	BN_free(ret);
265	0	return 0;
266	0	}
267
268		int BN_asc2bn(BIGNUM *bn, const char a)
269	0	{
270	0	const char *p = a;
271
272	0	if (*p == '-')
273	0	p++;
274
275	0	if (p[0] == '0' && (p[1] == 'X' \|\| p[1] == 'x')) {
276	0	if (!BN_hex2bn(bn, p + 2))
277	0	return 0;
278	0	} else {
279	0	if (!BN_dec2bn(bn, p))
280	0	return 0;
281	0	}
282		/* Don't set the negative flag if it's zero. */
283	0	if (a == '-' && (bn)->top != 0)
284	0	(*bn)->neg = 1;
285	0	return 1;
286	0	}