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_parse_asn1_unsigned_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
61int BN_marshal_asn1(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      /* The number must be padded with a leading zero if the high bit would
71       * otherwise be set or if |bn| is zero. */
72      (BN_num_bits(bn) % 8 == 0 && !CBB_add_u8(&child, 0x00)) ||
73      !BN_bn2cbb_padded(&child, BN_num_bytes(bn), bn) ||
74      !CBB_flush(cbb)) {
75    OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR);
76    return 0;
77  }
78
79  return 1;
80}
81