1 // SPDX-License-Identifier: BSD-2-Clause
2 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
3 *
4 * LibTomCrypt is a library that provides various cryptographic
5 * algorithms in a highly modular and flexible manner.
6 *
7 * The library is free for all purposes without any express
8 * guarantee it works.
9 */
10
11 #include "tomcrypt_private.h"
12
13 #ifdef LTC_MDH
14
15 /**
16 Import a DH key from a binary packet
17 @param in The packet to read
18 @param inlen The length of the input packet
19 @param key [out] Where to import the key to
20 @return CRYPT_OK if successful, on error all allocated memory is freed automatically
21 */
dh_import(const unsigned char * in,unsigned long inlen,dh_key * key)22 int dh_import(const unsigned char *in, unsigned long inlen, dh_key *key)
23 {
24 unsigned char flags[1];
25 int err;
26 unsigned long version;
27
28 LTC_ARGCHK(in != NULL);
29 LTC_ARGCHK(key != NULL);
30
31 /* init */
32 if ((err = mp_init_multi(&key->x, &key->y, &key->base, &key->prime, NULL)) != CRYPT_OK) {
33 return err;
34 }
35
36 /* find out what type of key it is */
37 err = der_decode_sequence_multi(in, inlen,
38 LTC_ASN1_SHORT_INTEGER, 1UL, &version,
39 LTC_ASN1_BIT_STRING, 1UL, &flags,
40 LTC_ASN1_EOL, 0UL, NULL);
41 if (err != CRYPT_OK && err != CRYPT_INPUT_TOO_LONG) {
42 goto error;
43 }
44
45 if (version == 0) {
46 if (flags[0] == 1) {
47 key->type = PK_PRIVATE;
48 if ((err = der_decode_sequence_multi(in, inlen,
49 LTC_ASN1_SHORT_INTEGER, 1UL, &version,
50 LTC_ASN1_BIT_STRING, 1UL, flags,
51 LTC_ASN1_INTEGER, 1UL, key->prime,
52 LTC_ASN1_INTEGER, 1UL, key->base,
53 LTC_ASN1_INTEGER, 1UL, key->x,
54 LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
55 goto error;
56 }
57 /* compute public key: y = (base ^ x) mod prime */
58 if ((err = mp_exptmod(key->base, key->x, key->prime, key->y)) != CRYPT_OK) {
59 goto error;
60 }
61 }
62 else if (flags[0] == 0) {
63 key->type = PK_PUBLIC;
64 if ((err = der_decode_sequence_multi(in, inlen,
65 LTC_ASN1_SHORT_INTEGER, 1UL, &version,
66 LTC_ASN1_BIT_STRING, 1UL, flags,
67 LTC_ASN1_INTEGER, 1UL, key->prime,
68 LTC_ASN1_INTEGER, 1UL, key->base,
69 LTC_ASN1_INTEGER, 1UL, key->y,
70 LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
71 goto error;
72 }
73 }
74 else {
75 err = CRYPT_INVALID_PACKET;
76 goto error;
77 }
78 }
79 else {
80 err = CRYPT_INVALID_PACKET;
81 goto error;
82 }
83
84 /* check public key */
85 if ((err = dh_check_pubkey(key)) != CRYPT_OK) {
86 goto error;
87 }
88
89 return CRYPT_OK;
90
91 error:
92 dh_free(key);
93 return err;
94 }
95
96 #endif /* LTC_MDH */
97
98 /* ref: $Format:%D$ */
99 /* git commit: $Format:%H$ */
100 /* commit time: $Format:%ai$ */
101