1 /* $OpenBSD: sm2_za.c,v 1.1.1.1 2021/08/18 16:04:32 tb Exp $ */
2 /*
3 * Copyright (c) 2017, 2019 Ribose Inc
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #ifndef OPENSSL_NO_SM2
19
20 #include <openssl/sm2.h>
21 #include <openssl/evp.h>
22 #include <openssl/bn.h>
23 #include <string.h>
24
25 int
sm2_compute_userid_digest(uint8_t * out,const EVP_MD * digest,uint8_t * uid,size_t uid_len,const EC_KEY * key)26 sm2_compute_userid_digest(uint8_t *out, const EVP_MD *digest, uint8_t *uid,
27 size_t uid_len, const EC_KEY *key)
28 {
29 const EC_GROUP *group;
30 EVP_MD_CTX *hash = NULL;
31 BN_CTX *ctx = NULL;
32 BIGNUM *p, *a, *b, *xG, *yG, *xA, *yA;
33 uint8_t *buf = NULL;
34 uint16_t entla;
35 uint8_t e_byte;
36 int bytes, p_bytes;
37 int rc = 0;
38
39 if ((group = EC_KEY_get0_group(key)) == NULL)
40 goto err;
41
42 if ((hash = EVP_MD_CTX_new()) == NULL)
43 goto err;
44
45 if ((ctx = BN_CTX_new()) == NULL)
46 goto err;
47
48 if ((p = BN_CTX_get(ctx)) == NULL)
49 goto err;
50 if ((a = BN_CTX_get(ctx)) == NULL)
51 goto err;
52 if ((b = BN_CTX_get(ctx)) == NULL)
53 goto err;
54 if ((xG = BN_CTX_get(ctx)) == NULL)
55 goto err;
56 if ((yG = BN_CTX_get(ctx)) == NULL)
57 goto err;
58 if ((xA = BN_CTX_get(ctx)) == NULL)
59 goto err;
60 if ((yA = BN_CTX_get(ctx)) == NULL)
61 goto err;
62
63 memset(out, 0, EVP_MD_size(digest));
64
65 if (!EVP_DigestInit(hash, digest))
66 goto err;
67
68 /*
69 * ZA=H256(ENTLA || IDA || a || b || xG || yG || xA || yA)
70 */
71
72 if (uid_len >= 8192)
73 goto err;
74
75 entla = (unsigned short)(8 * uid_len);
76
77 e_byte = entla >> 8;
78 if (!EVP_DigestUpdate(hash, &e_byte, 1))
79 goto err;
80
81 e_byte = entla & 0xFF;
82 if (!EVP_DigestUpdate(hash, &e_byte, 1))
83 goto err;
84
85 if (!EVP_DigestUpdate(hash, uid, uid_len))
86 goto err;
87
88 if (!EC_GROUP_get_curve(group, p, a, b, ctx))
89 goto err;
90
91 p_bytes = BN_num_bytes(p);
92
93 if ((buf = calloc(1, p_bytes)) == NULL)
94 goto err;
95
96 if ((bytes = BN_num_bytes(a)) > p_bytes)
97 goto err;
98 BN_bn2bin(a, buf + p_bytes - bytes);
99 if (!EVP_DigestUpdate(hash, buf, p_bytes))
100 goto err;
101
102 if ((bytes = BN_num_bytes(b)) > p_bytes)
103 goto err;
104 memset(buf, 0, p_bytes - bytes);
105 BN_bn2bin(b, buf + p_bytes - bytes);
106 if (!EVP_DigestUpdate(hash, buf, p_bytes))
107 goto err;
108
109 if (!EC_POINT_get_affine_coordinates(group,
110 EC_GROUP_get0_generator(group), xG, yG, ctx))
111 goto err;
112
113 if ((bytes = BN_num_bytes(xG)) > p_bytes)
114 goto err;
115 memset(buf, 0, p_bytes - bytes);
116 BN_bn2bin(xG, buf + p_bytes - bytes);
117
118 if (!EVP_DigestUpdate(hash, buf, p_bytes))
119 goto err;
120
121 if ((bytes = BN_num_bytes(yG)) > p_bytes)
122 goto err;
123 memset(buf, 0, p_bytes - bytes);
124 BN_bn2bin(yG, buf + p_bytes - bytes);
125
126 if (!EVP_DigestUpdate(hash, buf, p_bytes))
127 goto err;
128
129 if (!EC_POINT_get_affine_coordinates(group,
130 EC_KEY_get0_public_key(key), xA, yA, ctx))
131 goto err;
132
133 if ((bytes = BN_num_bytes(xA)) > p_bytes)
134 goto err;
135 memset(buf, 0, p_bytes - bytes);
136 BN_bn2bin(xA, buf + p_bytes - bytes);
137
138 if (!EVP_DigestUpdate(hash, buf, p_bytes))
139 goto err;
140
141 if ((bytes = BN_num_bytes(yA)) > p_bytes)
142 goto err;
143 memset(buf, 0, p_bytes - bytes);
144 BN_bn2bin(yA, buf + p_bytes - bytes);
145
146 if (!EVP_DigestUpdate(hash, buf, p_bytes))
147 goto err;
148
149 if (!EVP_DigestFinal(hash, out, NULL))
150 goto err;
151
152 rc = 1;
153
154 err:
155 free(buf);
156 BN_CTX_free(ctx);
157 EVP_MD_CTX_free(hash);
158 return rc;
159 }
160
161 #endif /* OPENSSL_NO_SM2 */
162