1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/*
* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <string.h>
#include <openssl/ct.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/x509.h>
#include "ct_locl.h"
typedef enum sct_signature_type_t {
SIGNATURE_TYPE_NOT_SET = -1,
SIGNATURE_TYPE_CERT_TIMESTAMP,
SIGNATURE_TYPE_TREE_HASH
} SCT_SIGNATURE_TYPE;
/*
* Update encoding for SCT signature verification/generation to supplied
* EVP_MD_CTX.
*/
static int sct_ctx_update(EVP_MD_CTX *ctx, const SCT_CTX *sctx, const SCT *sct)
{
unsigned char tmpbuf[12];
unsigned char *p, *der;
size_t derlen;
/*+
* digitally-signed struct {
* (1 byte) Version sct_version;
* (1 byte) SignatureType signature_type = certificate_timestamp;
* (8 bytes) uint64 timestamp;
* (2 bytes) LogEntryType entry_type;
* (? bytes) select(entry_type) {
* case x509_entry: ASN.1Cert;
* case precert_entry: PreCert;
* } signed_entry;
* (2 bytes + sct->ext_len) CtExtensions extensions;
* }
*/
if (sct->entry_type == CT_LOG_ENTRY_TYPE_NOT_SET)
return 0;
if (sct->entry_type == CT_LOG_ENTRY_TYPE_PRECERT && sctx->ihash == NULL)
return 0;
p = tmpbuf;
*p++ = sct->version;
*p++ = SIGNATURE_TYPE_CERT_TIMESTAMP;
l2n8(sct->timestamp, p);
s2n(sct->entry_type, p);
if (!EVP_DigestUpdate(ctx, tmpbuf, p - tmpbuf))
return 0;
if (sct->entry_type == CT_LOG_ENTRY_TYPE_X509) {
der = sctx->certder;
derlen = sctx->certderlen;
} else {
if (!EVP_DigestUpdate(ctx, sctx->ihash, sctx->ihashlen))
return 0;
der = sctx->preder;
derlen = sctx->prederlen;
}
/* If no encoding available, fatal error */
if (der == NULL)
return 0;
/* Include length first */
p = tmpbuf;
l2n3(derlen, p);
if (!EVP_DigestUpdate(ctx, tmpbuf, 3))
return 0;
if (!EVP_DigestUpdate(ctx, der, derlen))
return 0;
/* Add any extensions */
p = tmpbuf;
s2n(sct->ext_len, p);
if (!EVP_DigestUpdate(ctx, tmpbuf, 2))
return 0;
if (sct->ext_len && !EVP_DigestUpdate(ctx, sct->ext, sct->ext_len))
return 0;
return 1;
}
int SCT_CTX_verify(const SCT_CTX *sctx, const SCT *sct)
{
EVP_MD_CTX *ctx = NULL;
int ret = 0;
if (!SCT_is_complete(sct) || sctx->pkey == NULL ||
sct->entry_type == CT_LOG_ENTRY_TYPE_NOT_SET ||
(sct->entry_type == CT_LOG_ENTRY_TYPE_PRECERT && sctx->ihash == NULL)) {
CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_NOT_SET);
return 0;
}
if (sct->version != SCT_VERSION_V1) {
CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_UNSUPPORTED_VERSION);
return 0;
}
if (sct->log_id_len != sctx->pkeyhashlen ||
memcmp(sct->log_id, sctx->pkeyhash, sctx->pkeyhashlen) != 0) {
CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_LOG_ID_MISMATCH);
return 0;
}
if (sct->timestamp > sctx->epoch_time_in_ms) {
CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_FUTURE_TIMESTAMP);
return 0;
}
ctx = EVP_MD_CTX_new();
if (ctx == NULL)
goto end;
if (!EVP_DigestVerifyInit(ctx, NULL, EVP_sha256(), NULL, sctx->pkey))
goto end;
if (!sct_ctx_update(ctx, sctx, sct))
goto end;
/* Verify signature */
ret = EVP_DigestVerifyFinal(ctx, sct->sig, sct->sig_len);
/* If ret < 0 some other error: fall through without setting error */
if (ret == 0)
CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_INVALID_SIGNATURE);
end:
EVP_MD_CTX_free(ctx);
return ret;
}
|
