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<br clear="all"><div class="SECT1">
<h1 class="SECT1"><a name="XMLSEC-NOTES-SIGN">Signing a document.</a></h1>
<p>The typical siganture process includes following steps:
</p>
<p></p>
<ul>
<li><p> Prepare data for signature.
</p></li>
<li><p> Create or load signature template and select start
<a href="http://www.w3.org/TR/xmldsig-core/#sec-Signature" target="_top"><dsig:Signature/></a>
node.
</p></li>
<li><p> Create signature context <a href="xmlsec-xmldsig.html#XMLSECDSIGCTX">xmlSecDSigCtx</a>
using <a href="xmlsec-xmldsig.html#XMLSECDSIGCTXCREATE">xmlSecDSigCtxCreate</a> or
<a href="xmlsec-xmldsig.html#XMLSECDSIGCTXINITIALIZE">xmlSecDSigCtxInitialize</a>
functions.
</p></li>
<li><p> Load signature key in <a href="xmlsec-keysmngr.html#XMLSECKEYSMNGR">keys manager</a>
or generate a session key and set it in the signature context
(<code class="STRUCTFIELD">signKey</code> member of
<a href="xmlsec-xmldsig.html#XMLSECDSIGCTX">xmlSecDSigCtx</a> structure).
</p></li>
<li><p> Sign data by calling <a href="xmlsec-xmldsig.html#XMLSECDSIGCTXSIGN">xmlSecDSigCtxSign</a>
function.
</p></li>
<li><p> Check returned value and consume signed data.
</p></li>
<li><p> Destroy signature context <a href="xmlsec-xmldsig.html#XMLSECDSIGCTX">xmlSecDSigCtx</a>
using <a href="xmlsec-xmldsig.html#XMLSECDSIGCTXDESTROY">xmlSecDSigCtxDestroy</a> or
<a href="xmlsec-xmldsig.html#XMLSECDSIGCTXFINALIZE">xmlSecDSigCtxFinalize</a>
functions.
</p></li>
</ul>
<p> </p>
<div class="EXAMPLE">
<a name="AEN182"></a><p><b>Example 1. Signing a template.</b></p>
<pre class="PROGRAMLISTING">/**
* sign_file:
* @tmpl_file: the signature template file name.
* @key_file: the PEM private key file name.
*
* Signs the #tmpl_file using private key from #key_file.
*
* Returns 0 on success or a negative value if an error occurs.
*/
int
sign_file(const char* tmpl_file, const char* key_file) {
xmlDocPtr doc = NULL;
xmlNodePtr node = NULL;
xmlSecDSigCtxPtr dsigCtx = NULL;
int res = -1;
assert(tmpl_file);
assert(key_file);
/* load template */
doc = xmlParseFile(tmpl_file);
if ((doc == NULL) || (xmlDocGetRootElement(doc) == NULL)){
fprintf(stderr, "Error: unable to parse file \"%s\"\n", tmpl_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", tmpl_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 private key, assuming that there is not password */
dsigCtx->signKey = xmlSecCryptoAppKeyLoad(key_file, xmlSecKeyDataFormatPem, NULL, NULL, NULL);
if(dsigCtx->signKey == NULL) {
fprintf(stderr,"Error: failed to load private 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;
}
/* sign the template */
if(xmlSecDSigCtxSign(dsigCtx, node) < 0) {
fprintf(stderr,"Error: signature failed\n");
goto done;
}
/* print signed document to stdout */
xmlDocDump(stdout, doc);
/* success */
res = 0;
done:
/* cleanup */
if(dsigCtx != NULL) {
xmlSecDSigCtxDestroy(dsigCtx);
}
if(doc != NULL) {
xmlFreeDoc(doc);
}
return(res);
}
</pre>
<p><a href="xmlsec-examples-sign-template-file.html#XMLSEC-EXAMPLE-SIGN1">Full program listing</a></p>
<p><a href="xmlsec-examples-sign-template-file.html#XMLSEC-EXAMPLE-SIGN1-TMPL">Simple signature template file</a></p>
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