Example 1. Verifying a document.
/**
* 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);
}
Full Program Listing
