1/* Copyright (c) 2015, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15#include <openssl/bn.h>
16
17#include <openssl/bytestring.h>
18#include <openssl/err.h>
19
20
21int BN_parse_asn1_unsigned(CBS *cbs, BIGNUM *ret) {
22 CBS child;
23 if (!CBS_get_asn1(cbs, &child, CBS_ASN1_INTEGER) ||
24 CBS_len(&child) == 0) {
25 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);
26 return 0;
27 }
28
29 if (CBS_data(&child)[0] & 0x80) {
30 OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER);
31 return 0;
32 }
33
34 // INTEGERs must be minimal.
35 if (CBS_data(&child)[0] == 0x00 &&
36 CBS_len(&child) > 1 &&
37 !(CBS_data(&child)[1] & 0x80)) {
38 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);
39 return 0;
40 }
41
42 return BN_bin2bn(CBS_data(&child), CBS_len(&child), ret) != NULL;
43}
44
45int BN_marshal_asn1(CBB *cbb, const BIGNUM *bn) {
46 // Negative numbers are unsupported.
47 if (BN_is_negative(bn)) {
48 OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER);
49 return 0;
50 }
51
52 CBB child;
53 if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER) ||
54 // The number must be padded with a leading zero if the high bit would
55 // otherwise be set or if |bn| is zero.
56 (BN_num_bits(bn) % 8 == 0 && !CBB_add_u8(&child, 0x00)) ||
57 !BN_bn2cbb_padded(&child, BN_num_bytes(bn), bn) ||
58 !CBB_flush(cbb)) {
59 OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR);
60 return 0;
61 }
62
63 return 1;
64}
65