XML Security Library

LibXML2
LibXSLT
OpenSSL

Signing a template file.

sign1.c

/** 
 * XML Security Library example: Signing a template file.
 * 
 * Signs a template file using a key from PEM file
 * 
 * Usage: 
 *      ./sign1 <xml-tmpl> <pem-key> 
 *
 * Example:
 *      ./sign1 sign1-tmpl.xml rsakey.pem > sign1-res.xml
 *
 * The result signature could be validated using verify1 example:
 *      ./verify1 sign1-res.xml rsapub.pem
 *
 * This is free software; see Copyright file in the source
 * distribution for preciese wording.
 * 
 * Copyright (C) 2002-2016 Aleksey Sanin <aleksey@aleksey.com>. All Rights Reserved.
 */
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <libxml/tree.h>
#include <libxml/xmlmemory.h>
#include <libxml/parser.h>

#ifndef XMLSEC_NO_XSLT
#include <libxslt/xslt.h>
#include <libxslt/security.h>
#endif /* XMLSEC_NO_XSLT */

#include <xmlsec/xmlsec.h>
#include <xmlsec/xmltree.h>
#include <xmlsec/xmldsig.h>
#include <xmlsec/crypto.h>

int sign_file(const char* tmpl_file, const char* key_file);

int 
main(int argc, char **argv) {
#ifndef XMLSEC_NO_XSLT
    xsltSecurityPrefsPtr xsltSecPrefs = NULL;
#endif /* XMLSEC_NO_XSLT */

    assert(argv);

    if(argc != 3) {
        fprintf(stderr, "Error: wrong number of arguments.\n");
        fprintf(stderr, "Usage: %s <tmpl-file> <key-file>\n", argv[0]);
        return(1);
    }

    /* Init libxml and libxslt libraries */
    xmlInitParser();
    LIBXML_TEST_VERSION
    xmlLoadExtDtdDefaultValue = XML_DETECT_IDS | XML_COMPLETE_ATTRS;
    xmlSubstituteEntitiesDefault(1);
#ifndef XMLSEC_NO_XSLT
    xmlIndentTreeOutput = 1; 
#endif /* XMLSEC_NO_XSLT */

    /* Init libxslt */
#ifndef XMLSEC_NO_XSLT
    /* disable everything */
    xsltSecPrefs = xsltNewSecurityPrefs(); 
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_READ_FILE,        xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_WRITE_FILE,       xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_CREATE_DIRECTORY, xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_READ_NETWORK,     xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_WRITE_NETWORK,    xsltSecurityForbid);
    xsltSetDefaultSecurityPrefs(xsltSecPrefs); 
#endif /* XMLSEC_NO_XSLT */                

    /* Init xmlsec library */
    if(xmlSecInit() < 0) {
        fprintf(stderr, "Error: xmlsec initialization failed.\n");
        return(-1);
    }

    /* Check loaded library version */
    if(xmlSecCheckVersion() != 1) {
        fprintf(stderr, "Error: loaded xmlsec library version is not compatible.\n");
        return(-1);
    }

    /* Load default crypto engine if we are supporting dynamic
     * loading for xmlsec-crypto libraries. Use the crypto library
     * name ("openssl", "nss", etc.) to load corresponding 
     * xmlsec-crypto library.
     */
#ifdef XMLSEC_CRYPTO_DYNAMIC_LOADING
    if(xmlSecCryptoDLLoadLibrary(NULL) < 0) {
        fprintf(stderr, "Error: unable to load default xmlsec-crypto library. Make sure\n"
                        "that you have it installed and check shared libraries path\n"
                        "(LD_LIBRARY_PATH and/or LTDL_LIBRARY_PATH) envornment variables.\n");
        return(-1);     
    }
#endif /* XMLSEC_CRYPTO_DYNAMIC_LOADING */

    /* Init crypto library */
    if(xmlSecCryptoAppInit(NULL) < 0) {
        fprintf(stderr, "Error: crypto initialization failed.\n");
        return(-1);
    }

    /* Init xmlsec-crypto library */
    if(xmlSecCryptoInit() < 0) {
        fprintf(stderr, "Error: xmlsec-crypto initialization failed.\n");
        return(-1);
    }

    if(sign_file(argv[1], argv[2]) < 0) {
        return(-1);
    }    
    
    /* Shutdown xmlsec-crypto library */
    xmlSecCryptoShutdown();
    
    /* Shutdown crypto library */
    xmlSecCryptoAppShutdown();
    
    /* Shutdown xmlsec library */
    xmlSecShutdown();

    /* Shutdown libxslt/libxml */
#ifndef XMLSEC_NO_XSLT
    xsltFreeSecurityPrefs(xsltSecPrefs);
    xsltCleanupGlobals();
#endif /* XMLSEC_NO_XSLT */
    xmlCleanupParser();
    
    return(0);
}

/** 
 * 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);
}

sign1-tmpl.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- 
XML Security Library example: Simple signature template file for sign1 example. 
-->
<Envelope xmlns="urn:envelope">
  <Data>
	Hello, World!
  </Data>
  <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
    <SignedInfo>
      <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
      <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
      <Reference URI="">
        <Transforms>
          <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" />
        </Transforms>
        <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
        <DigestValue></DigestValue>
      </Reference>
    </SignedInfo>
    <SignatureValue/>
    <KeyInfo>
	<KeyName/>
    </KeyInfo>
  </Signature>
</Envelope>

sign1-res.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- 
XML Security Library example: Simple signature template file for sign1 example. 
-->
<Envelope xmlns="urn:envelope">
  <Data>
	Hello, World!
  </Data>
  <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
    <SignedInfo>
      <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
      <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
      <Reference URI="">
        <Transforms>
          <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
        </Transforms>
        <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
        <DigestValue>9H/rQr2Axe9hYTV2n/tCp+3UIQQ=</DigestValue>
      </Reference>
    </SignedInfo>
    <SignatureValue>fDKK0so/zFcmmq2X+BaVFmS0t8KB7tyW53YN6n221OArzGCs4OyWsAjj/BUR+wNF
elOnt4fo2gPK1a3IVEhMGg==</SignatureValue>
    <KeyInfo>
	<KeyName>rsakey.pem</KeyName>
    </KeyInfo>
  </Signature>
</Envelope>