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
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Verifying a signed document: XML Security Library Reference Manual</title>
<meta name="generator" content="DocBook XSL Stylesheets Vsnapshot">
<link rel="home" href="index.html" title="XML Security Library Reference Manual">
<link rel="up" href="xmlsec-notes-verify-decrypt.html" title="Verifing and decrypting documents.">
<link rel="prev" href="xmlsec-notes-verify-decrypt.html" title="Verifing and decrypting documents.">
<link rel="next" href="xmlsec-notes-decrypt.html" title="Decrypting an encrypted document">
<meta name="generator" content="GTK-Doc V1.34.0 (XML mode)">
<link rel="stylesheet" href="style.css" type="text/css">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="5"><tr valign="middle">
<td width="100%" align="left" class="shortcuts"></td>
<td><a accesskey="h" href="index.html"><img src="home.png" width="16" height="16" border="0" alt="Home"></a></td>
<td><a accesskey="u" href="xmlsec-notes-verify-decrypt.html"><img src="up.png" width="16" height="16" border="0" alt="Up"></a></td>
<td><a accesskey="p" href="xmlsec-notes-verify-decrypt.html"><img src="left.png" width="16" height="16" border="0" alt="Prev"></a></td>
<td><a accesskey="n" href="xmlsec-notes-decrypt.html"><img src="right.png" width="16" height="16" border="0" alt="Next"></a></td>
</tr></table>
<div class="sect1">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="xmlsec-notes-verify"></a>Verifying a signed document</h2></div></div></div>
<p>The typical signature verification process includes following steps:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p>
Load keys, X509 certificates, etc. in the <a class="link" href="xmlsec-keysmngr.html#xmlSecKeysMngr" title="struct xmlSecKeysMngr">keys manager</a> .
</p></li>
<li class="listitem"><p>
Create signature context <a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtx" title="struct xmlSecDSigCtx">xmlSecDSigCtx</a>
using <a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtxCreate" title="xmlSecDSigCtxCreate ()">xmlSecDSigCtxCreate</a> or
<a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtxInitialize" title="xmlSecDSigCtxInitialize ()">xmlSecDSigCtxInitialize</a>
functions.
</p></li>
<li class="listitem"><p>
Select start verification
<a class="ulink" href="" target="_top"><dsig:Signature/></a>
node in the signed XML document.
</p></li>
<li class="listitem"><p>
Verify signature by calling <a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtxVerify" title="xmlSecDSigCtxVerify ()">xmlSecDSigCtxVerify</a>
function.
</p></li>
<li class="listitem"><p>
Check returned value and verification status (<em class="structfield"><code>status</code></em>
member of <a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtx" title="struct xmlSecDSigCtx">xmlSecDSigCtx</a> structure).
If necessary, consume returned data from the <a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtx" title="struct xmlSecDSigCtx">context</a>.
</p></li>
<li class="listitem"><p>
Destroy signature context <a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtx" title="struct xmlSecDSigCtx">xmlSecDSigCtx</a>
using <a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtxDestroy" title="xmlSecDSigCtxDestroy ()">xmlSecDSigCtxDestroy</a> or
<a class="link" href="xmlsec-xmldsig.html#xmlSecDSigCtxFinalize" title="xmlSecDSigCtxFinalize ()">xmlSecDSigCtxFinalize</a>
functions.
</p></li>
</ul></div>
<p>
</p>
<p>
</p>
<div class="example">
<a name="id-1.2.8.3.3.1"></a><p class="title"><b>Example 14. Verifying a document.</b></p>
<div class="example-contents">
<pre class="programlisting">
/**
* verify_file:
* @xml_file: the signed XML file name.
* @key_file: the PEM public key file name.
*
* Verifies XML signature in #xml_file using public key from #key_file.
*
* Returns 0 on success or a negative value if an error occurs.
*/
int
verify_file(const char* xml_file, const char* key_file) {
xmlDocPtr doc = NULL;
xmlNodePtr node = NULL;
xmlSecDSigCtxPtr dsigCtx = NULL;
int res = -1;
assert(xml_file);
assert(key_file);
/* load file */
doc = xmlParseFile(xml_file);
if ((doc == NULL) || (xmlDocGetRootElement(doc) == NULL)){
fprintf(stderr, "Error: unable to parse file \"%s\"\n", xml_file);
goto done;
}
/* find start node */
node = xmlSecFindNode(xmlDocGetRootElement(doc), xmlSecNodeSignature, xmlSecDSigNs);
if(node == NULL) {
fprintf(stderr, "Error: start node not found in \"%s\"\n", xml_file);
goto done;
}
/* create signature context, we don't need keys manager in this example */
dsigCtx = xmlSecDSigCtxCreate(NULL);
if(dsigCtx == NULL) {
fprintf(stderr,"Error: failed to create signature context\n");
goto done;
}
/* load public key */
dsigCtx->signKey = xmlSecCryptoAppKeyLoad(key_file,xmlSecKeyDataFormatPem, NULL, NULL, NULL);
if(dsigCtx->signKey == NULL) {
fprintf(stderr,"Error: failed to load public pem key from \"%s\"\n", key_file);
goto done;
}
/* set key name to the file name, this is just an example! */
if(xmlSecKeySetName(dsigCtx->signKey, key_file) < 0) {
fprintf(stderr,"Error: failed to set key name for key from \"%s\"\n", key_file);
goto done;
}
/* Verify signature */
if(xmlSecDSigCtxVerify(dsigCtx, node) < 0) {
fprintf(stderr,"Error: signature verify\n");
goto done;
}
/* print verification result to stdout */
if(dsigCtx->status == xmlSecDSigStatusSucceeded) {
fprintf(stdout, "Signature is OK\n");
} else {
fprintf(stdout, "Signature is INVALID\n");
}
/* success */
res = 0;
done:
/* cleanup */
if(dsigCtx != NULL) {
xmlSecDSigCtxDestroy(dsigCtx);
}
if(doc != NULL) {
xmlFreeDoc(doc);
}
return(res);
}
</pre>
<p><a class="link" href="xmlsec-verify-with-key.html#xmlsec-example-verify1" title="verify1.c">Full Program Listing</a></p>
</div>
</div>
<p><br class="example-break">
</p>
</div>
<div class="footer">
<hr>Generated by GTK-Doc V1.34.0</div>
</body>
</html>
|
