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
BN_cbs2unsigned(CBS * cbs,BIGNUM * ret)21 int BN_cbs2unsigned(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
BN_cbs2unsigned_buggy(CBS * cbs,BIGNUM * ret)45 int BN_cbs2unsigned_buggy(CBS *cbs, BIGNUM *ret) {
46 CBS child;
47 if (!CBS_get_asn1(cbs, &child, CBS_ASN1_INTEGER) ||
48 CBS_len(&child) == 0) {
49 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);
50 return 0;
51 }
52
53 /* This function intentionally does not reject negative numbers or non-minimal
54 * encodings. Estonian IDs issued between September 2014 to September 2015 are
55 * broken. See https://crbug.com/532048 and https://crbug.com/534766.
56 *
57 * TODO(davidben): Remove this code and callers in March 2016. */
58 return BN_bin2bn(CBS_data(&child), CBS_len(&child), ret) != NULL;
59 }
60
BN_bn2cbb(CBB * cbb,const BIGNUM * bn)61 int BN_bn2cbb(CBB *cbb, const BIGNUM *bn) {
62 /* Negative numbers are unsupported. */
63 if (BN_is_negative(bn)) {
64 OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER);
65 return 0;
66 }
67
68 CBB child;
69 if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER)) {
70 OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR);
71 return 0;
72 }
73
74 /* The number must be padded with a leading zero if the high bit would
75 * otherwise be set (or |bn| is zero). */
76 if (BN_num_bits(bn) % 8 == 0 &&
77 !CBB_add_u8(&child, 0x00)) {
78 OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR);
79 return 0;
80 }
81
82 uint8_t *out;
83 if (!CBB_add_space(&child, &out, BN_num_bytes(bn))) {
84 OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR);
85 return 0;
86 }
87 BN_bn2bin(bn, out);
88 if (!CBB_flush(cbb)) {
89 OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR);
90 return 0;
91 }
92 return 1;
93 }
94