Verifying a signature with additional restrictions.: XML Security Library Reference Manual

## Verifying a signature with additional restrictions.

### verify4.c

    /**
     * XML Security Library example: Verifying a simple SAML response with X509 certificate
     *
     * Verifies a simple SAML response. In addition to regular verification
     * we ensure that the signature has only one <dsig:Reference/> element
     * with an empty or NULL URI attribute and one enveloped signature transform
     * as it is required by SAML specification.
     *
     * This example was developed and tested with OpenSSL crypto library. The
     * certificates management policies for another crypto library may break it.
     *
     * Usage:
     *      verify4 <signed-file> <trusted-cert-pem-file1> [<trusted-cert-pem-file2> [...]]
     *
     * Example (success):
     *      ./verify4 verify4-res.xml ca2cert.pem cacert.pem
     *
     * Example (failure):
     *      ./verify4 verify4-bad-res.xml ca2cert.pem cacert.pem
     * In the same time, verify3 example successfully verifies this signature:
     *      ./verify3 verify4-bad-res.xml ca2cert.pem cacert.pem
     *
     * This is free software; see Copyright file in the source
     * distribution for preciese wording.
     *
     * Copyright (C) 2002-2024 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>

    xmlSecKeysMngrPtr load_trusted_certs(char** files, int files_size);
    int verify_file(xmlSecKeysMngrPtr mngr, const char* xml_file);

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

        assert(argv);

        if(argc < 3) {
            fprintf(stderr, "Error: wrong number of arguments.\n");
            fprintf(stderr, "Usage: %s <xml-file> <cert-file1> [<cert-file2> [...]]\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) environment 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);
        }

        /* create keys manager and load trusted certificates */
        mngr = load_trusted_certs(&(argv[2]), argc - 2);
        if(mngr == NULL) {
            return(-1);
        }

        /* verify file */
        if(verify_file(mngr, argv[1]) < 0) {
            xmlSecKeysMngrDestroy(mngr);
            return(-1);
        }

        /* destroy keys manager */
        xmlSecKeysMngrDestroy(mngr);

        /* 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);
    }

    /**
     * load_trusted_certs:
     * @files:              the list of filenames.
     * @files_size:         the number of filenames in #files.
     *
     * Creates simple keys manager and load trusted certificates from PEM #files.
     * The caller is responsible for destroying returned keys manager using
     * @xmlSecKeysMngrDestroy.
     *
     * Returns the pointer to newly created keys manager or NULL if an error
     * occurs.
     */
    xmlSecKeysMngrPtr
    load_trusted_certs(char** files, int files_size) {
        xmlSecKeysMngrPtr mngr;
        int i;

        assert(files);
        assert(files_size > 0);

        /* create and initialize keys manager, we use a simple list based
         * keys manager, implement your own xmlSecKeysStore klass if you need
         * something more sophisticated
         */
        mngr = xmlSecKeysMngrCreate();
        if(mngr == NULL) {
            fprintf(stderr, "Error: failed to create keys manager.\n");
            return(NULL);
        }
        if(xmlSecCryptoAppDefaultKeysMngrInit(mngr) < 0) {
            fprintf(stderr, "Error: failed to initialize keys manager.\n");
            xmlSecKeysMngrDestroy(mngr);
            return(NULL);
        }

        for(i = 0; i < files_size; ++i) {
            assert(files[i]);

            /* load trusted cert */
            if(xmlSecCryptoAppKeysMngrCertLoad(mngr, files[i], xmlSecKeyDataFormatPem, xmlSecKeyDataTypeTrusted) < 0) {
                fprintf(stderr,"Error: failed to load pem certificate from \"%s\"\n", files[i]);
                xmlSecKeysMngrDestroy(mngr);
                return(NULL);
            }
        }

        return(mngr);
    }

    /**
     * verify_file:
     * @mngr:               the pointer to keys manager.
     * @xml_file:           the signed XML file name.
     *
     * Verifies XML signature in #xml_file.
     *
     * Returns 0 on success or a negative value if an error occurs.
     */
    int
    verify_file(xmlSecKeysMngrPtr mngr, const char* xml_file) {
        xmlDocPtr doc = NULL;
        xmlNodePtr node = NULL;
        xmlSecDSigCtxPtr dsigCtx = NULL;
        int res = -1;

        assert(mngr);
        assert(xml_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 */
        dsigCtx = xmlSecDSigCtxCreate(mngr);
        if(dsigCtx == NULL) {
            fprintf(stderr,"Error: failed to create signature context\n");
            goto done;
        }

        /* limit the Reference URI attributes to empty or NULL */
        dsigCtx->enabledReferenceUris = xmlSecTransformUriTypeEmpty;

        /* limit allowed transforms for signature and reference processing */
        if((xmlSecDSigCtxEnableSignatureTransform(dsigCtx, xmlSecTransformInclC14NId) < 0) ||
           (xmlSecDSigCtxEnableSignatureTransform(dsigCtx, xmlSecTransformExclC14NId) < 0) ||
           (xmlSecDSigCtxEnableSignatureTransform(dsigCtx, xmlSecTransformSha1Id) < 0) ||
           (xmlSecDSigCtxEnableSignatureTransform(dsigCtx, xmlSecTransformRsaSha1Id) < 0)) {

            fprintf(stderr,"Error: failed to limit allowed signature transforms\n");
            goto done;
        }
        if((xmlSecDSigCtxEnableReferenceTransform(dsigCtx, xmlSecTransformInclC14NId) < 0) ||
           (xmlSecDSigCtxEnableReferenceTransform(dsigCtx, xmlSecTransformExclC14NId) < 0) ||
           (xmlSecDSigCtxEnableReferenceTransform(dsigCtx, xmlSecTransformSha1Id) < 0) ||
           (xmlSecDSigCtxEnableReferenceTransform(dsigCtx, xmlSecTransformEnvelopedId) < 0)) {

            fprintf(stderr,"Error: failed to limit allowed reference transforms\n");
            goto done;
        }

        /* in addition, limit possible key data to valid X509 certificates only */
        if(xmlSecPtrListAdd(&(dsigCtx->keyInfoReadCtx.enabledKeyData), BAD_CAST xmlSecKeyDataX509Id) < 0) {
            fprintf(stderr,"Error: failed to limit allowed key data\n");
            goto done;
        }

        /* Verify signature */
        if(xmlSecDSigCtxVerify(dsigCtx, node) < 0) {
            fprintf(stderr,"Error: signature verify\n");
            goto done;
        }

        /* check that we have only one Reference */
        if((dsigCtx->status == xmlSecDSigStatusSucceeded) &&
            (xmlSecPtrListGetSize(&(dsigCtx->signedInfoReferences)) != 1)) {

            fprintf(stderr,"Error: only one reference is allowed\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);
    }

### verify4-tmpl.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <!--
    XML Security Library example: A simple SAML response template (verify4 example).

    Sign it using the following command (replace __ with double dashes):

     ../apps/xmlsec sign __privkey rsakey.pem,rsacert.pem __output verify4-res.xml verify4-tmpl.xml
    -->
    <Response xmlns="urn:oasis:names:tc:SAML:1.0:protocol" xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" IssueInstant="2002-04-18T16:56:54Z" MajorVersion="1" MinorVersion="0" Recipient="https://shire.target.com" ResponseID="7ddc31-ed4a03d703-FB24AD27D96135B68C99FB9AACFE2FFC">
      <dsig:Signature xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">
        <dsig:SignedInfo>
          <dsig:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
          <dsig:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
          <dsig:Reference URI="">
            <dsig:Transforms>
              <dsig:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
            </dsig:Transforms>
            <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
            <dsig:DigestValue/>
          </dsig:Reference>
        </dsig:SignedInfo>
        <dsig:SignatureValue/>
        <dsig:KeyInfo>
          <dsig:X509Data/>
        </dsig:KeyInfo>
      </dsig:Signature>
      <Status>
        <StatusCode Value="samlp:Success"/>
      </Status>
      <Assertion xmlns="urn:oasis:names:tc:SAML:1.0:assertion" AssertionID="7ddc31-ed4a03d735-FB24AD27D96135B68C99FB9AACFE2FFC" IssueInstant="2002-04-18T16:56:54Z" Issuer="hs.osu.edu" MajorVersion="1" MinorVersion="0">
        <Conditions NotBefore="2002-04-18T16:56:54Z" NotOnOrAfter="2002-04-18T17:01:54Z">
          <AudienceRestrictionCondition>
            <Audience>http://middleware.internet2.edu/shibboleth/clubs/clubshib/1.0/</Audience>
          </AudienceRestrictionCondition>
        </Conditions>
        <AuthenticationStatement AuthenticationInstant="2002-04-18T16:56:53Z" AuthenticationMethod="urn:mace:shibboleth:authmethod">
          <Subject>
            <NameIdentifier Format="urn:mace:shibboleth:1.0:handle" NameQualifier="osu.edu">foo</NameIdentifier>
            <SubjectConfirmation>
              <ConfirmationMethod>urn:oasis:names:tc:SAML:1.0:cm:Bearer</ConfirmationMethod>
            </SubjectConfirmation>
          </Subject>
          <SubjectLocality IPAddress="127.0.0.1"/>
          <AuthorityBinding AuthorityKind="samlp:AttributeQuery" Binding="urn:oasis:names:tc:SAML:1.0:bindings:SOAP-binding" Location="https://aa.osu.edu/"/>
        </AuthenticationStatement>
      </Assertion>
    </Response>

### verify4-res.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <!--
    XML Security Library example: A simple SAML response template (verify4 example).

    Sign it using the following command (replace __ with double dashes):

     ../apps/xmlsec sign __privkey rsakey.pem,rsacert.pem __output verify4-res.xml verify4-tmpl.xml
    -->
    <Response xmlns="urn:oasis:names:tc:SAML:1.0:protocol" xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" IssueInstant="2002-04-18T16:56:54Z" MajorVersion="1" MinorVersion="0" Recipient="https://shire.target.com" ResponseID="7ddc31-ed4a03d703-FB24AD27D96135B68C99FB9AACFE2FFC">
      <dsig:Signature xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">
        <dsig:SignedInfo>
          <dsig:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
          <dsig:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
          <dsig:Reference URI="">
            <dsig:Transforms>
              <dsig:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
            </dsig:Transforms>
            <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
            <dsig:DigestValue>t1nvDq1bZXEhBIXc/DHcqIrjRyI=</dsig:DigestValue>
          </dsig:Reference>
        </dsig:SignedInfo>
        <dsig:SignatureValue>cj28Qr33wTqwHJzpI+7Mth7HUTr9MKACSH4x/1/AO64FEGiQRoOBB8XuUHZ8tzkP
    Azy8FwoZE/Jv5d/0N3ru4Q==</dsig:SignatureValue>
        <dsig:KeyInfo>
          <dsig:X509Data>
    <dsig:X509Certificate>MIIDpzCCA1GgAwIBAgIJAK+ii7kzrdqvMA0GCSqGSIb3DQEBBQUAMIGcMQswCQYD
    VQQGEwJVUzETMBEGA1UECBMKQ2FsaWZvcm5pYTE9MDsGA1UEChM0WE1MIFNlY3Vy
    aXR5IExpYnJhcnkgKGh0dHA6Ly93d3cuYWxla3NleS5jb20veG1sc2VjKTEWMBQG
    A1UEAxMNQWxla3NleSBTYW5pbjEhMB8GCSqGSIb3DQEJARYSeG1sc2VjQGFsZWtz
    ZXkuY29tMCAXDTE0MDUyMzE3NTUzNFoYDzIxMTQwNDI5MTc1NTM0WjCBxzELMAkG
    A1UEBhMCVVMxEzARBgNVBAgTCkNhbGlmb3JuaWExPTA7BgNVBAoTNFhNTCBTZWN1
    cml0eSBMaWJyYXJ5IChodHRwOi8vd3d3LmFsZWtzZXkuY29tL3htbHNlYykxKTAn
    BgNVBAsTIFRlc3QgVGhpcmQgTGV2ZWwgUlNBIENlcnRpZmljYXRlMRYwFAYDVQQD
    Ew1BbGVrc2V5IFNhbmluMSEwHwYJKoZIhvcNAQkBFhJ4bWxzZWNAYWxla3NleS5j
    b20wXDANBgkqhkiG9w0BAQEFAANLADBIAkEA09BtD3aeVt6DVDkk0dI7Vh7Ljqdn
    sYmW0tbDVxxK+nume+Z9Sb4znbUKkWl+vgQATdRUEyhT2P+Gqrd0UBzYfQIDAQAB
    o4IBRTCCAUEwDAYDVR0TBAUwAwEB/zAsBglghkgBhvhCAQ0EHxYdT3BlblNTTCBH
    ZW5lcmF0ZWQgQ2VydGlmaWNhdGUwHQYDVR0OBBYEFNf0xkZ3zjcEI60pVPuwDqTM
    QygZMIHjBgNVHSMEgdswgdiAFP7k7FMk8JWVxxC14US1XTllWuN+oYG0pIGxMIGu
    MQswCQYDVQQGEwJVUzETMBEGA1UECBMKQ2FsaWZvcm5pYTE9MDsGA1UEChM0WE1M
    IFNlY3VyaXR5IExpYnJhcnkgKGh0dHA6Ly93d3cuYWxla3NleS5jb20veG1sc2Vj
    KTEQMA4GA1UECxMHUm9vdCBDQTEWMBQGA1UEAxMNQWxla3NleSBTYW5pbjEhMB8G
    CSqGSIb3DQEJARYSeG1sc2VjQGFsZWtzZXkuY29tggkAr6KLuTOt2q0wDQYJKoZI
    hvcNAQEFBQADQQAOXBj0yICp1RmHXqnUlsppryLCW3pKBD1dkb4HWarO7RjA1yJJ
    fBjXssrERn05kpBcrRfzou4r3DCgQFPhjxga</dsig:X509Certificate>
    </dsig:X509Data>
        </dsig:KeyInfo>
      </dsig:Signature>
      <Status>
        <StatusCode Value="samlp:Success"/>
      </Status>
      <Assertion xmlns="urn:oasis:names:tc:SAML:1.0:assertion" AssertionID="7ddc31-ed4a03d735-FB24AD27D96135B68C99FB9AACFE2FFC" IssueInstant="2002-04-18T16:56:54Z" Issuer="hs.osu.edu" MajorVersion="1" MinorVersion="0">
        <Conditions NotBefore="2002-04-18T16:56:54Z" NotOnOrAfter="2002-04-18T17:01:54Z">
          <AudienceRestrictionCondition>
            <Audience>http://middleware.internet2.edu/shibboleth/clubs/clubshib/1.0/</Audience>
          </AudienceRestrictionCondition>
        </Conditions>
        <AuthenticationStatement AuthenticationInstant="2002-04-18T16:56:53Z" AuthenticationMethod="urn:mace:shibboleth:authmethod">
          <Subject>
            <NameIdentifier Format="urn:mace:shibboleth:1.0:handle" NameQualifier="osu.edu">foo</NameIdentifier>
            <SubjectConfirmation>
              <ConfirmationMethod>urn:oasis:names:tc:SAML:1.0:cm:Bearer</ConfirmationMethod>
            </SubjectConfirmation>
          </Subject>
          <SubjectLocality IPAddress="127.0.0.1"/>
          <AuthorityBinding AuthorityKind="samlp:AttributeQuery" Binding="urn:oasis:names:tc:SAML:1.0:bindings:SOAP-binding" Location="https://aa.osu.edu/"/>
        </AuthenticationStatement>
      </Assertion>
    </Response>

### verify4-bad-tmpl.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <!--
    XML Security Library example: A simple bad SAML response template (verify4 example).

    Sign it using the following command (replace __ with double dashes):

     ../apps/xmlsec sign __privkey rsakey.pem,rsacert.pem __output verify4--bad-res.xml verify4-bad-tmpl.xml
    -->
    <Response xmlns="urn:oasis:names:tc:SAML:1.0:protocol" xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" IssueInstant="2002-04-18T16:56:54Z" MajorVersion="1" MinorVersion="0" Recipient="https://shire.target.com" ResponseID="7ddc31-ed4a03d703-FB24AD27D96135B68C99FB9AACFE2FFC">
      <dsig:Signature xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">
        <dsig:SignedInfo>
          <dsig:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
          <dsig:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
          <dsig:Reference URI="">
            <dsig:Transforms>
              <dsig:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
              <dsig:Transform Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
                <dsig:XPath xmlns:samlp_xpath="urn:oasis:names:tc:SAML:1.0:protocol" >
                  count(ancestor-or-self::samlp_xpath:Response |
                  here()/ancestor::samlp_xpath:Response[1]) =
                  count(ancestor-or-self::samlp_xpath:Response)
                </dsig:XPath>
              </dsig:Transform>
            </dsig:Transforms>
            <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
            <dsig:DigestValue/>
          </dsig:Reference>
        </dsig:SignedInfo>
        <dsig:SignatureValue/>
        <dsig:KeyInfo>
          <dsig:X509Data/>
        </dsig:KeyInfo>
      </dsig:Signature>
      <Status>
        <StatusCode Value="samlp:Success"/>
      </Status>
      <Assertion xmlns="urn:oasis:names:tc:SAML:1.0:assertion" AssertionID="7ddc31-ed4a03d735-FB24AD27D96135B68C99FB9AACFE2FFC" IssueInstant="2002-04-18T16:56:54Z" Issuer="hs.osu.edu" MajorVersion="1" MinorVersion="0">
        <Conditions NotBefore="2002-04-18T16:56:54Z" NotOnOrAfter="2002-04-18T17:01:54Z">
          <AudienceRestrictionCondition>
            <Audience>http://middleware.internet2.edu/shibboleth/clubs/clubshib/1.0/</Audience>
          </AudienceRestrictionCondition>
        </Conditions>
        <AuthenticationStatement AuthenticationInstant="2002-04-18T16:56:53Z" AuthenticationMethod="urn:mace:shibboleth:authmethod">
          <Subject>
            <NameIdentifier Format="urn:mace:shibboleth:1.0:handle" NameQualifier="osu.edu">foo</NameIdentifier>
            <SubjectConfirmation>
              <ConfirmationMethod>urn:oasis:names:tc:SAML:1.0:cm:Bearer</ConfirmationMethod>
            </SubjectConfirmation>
          </Subject>
          <SubjectLocality IPAddress="127.0.0.1"/>
          <AuthorityBinding AuthorityKind="samlp:AttributeQuery" Binding="urn:oasis:names:tc:SAML:1.0:bindings:SOAP-binding" Location="https://aa.osu.edu/"/>
        </AuthenticationStatement>
      </Assertion>
    </Response>

### verify4-bad-res.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <!--
    XML Security Library example: A simple bad SAML response (verify4 example).

    This file could be verified with verify3 example (signature is valid)
    but verify4 example fails because of XPath transform which is not allowed
    in a simple SAML response.

    This file was created from a template with the following command (replace __ with double dashes):
     ../apps/xmlsec sign __privkey rsakey.pem,rsacert.pem __output verify4-bad-res.xml verify4-bad-tmpl.xml
    -->
    <Response xmlns="urn:oasis:names:tc:SAML:1.0:protocol" xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" IssueInstant="2002-04-18T16:56:54Z" MajorVersion="1" MinorVersion="0" Recipient="https://shire.target.com" ResponseID="7ddc31-ed4a03d703-FB24AD27D96135B68C99FB9AACFE2FFC">
      <dsig:Signature xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">
        <dsig:SignedInfo>
          <dsig:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
          <dsig:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
          <dsig:Reference URI="">
            <dsig:Transforms>
              <dsig:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
              <dsig:Transform Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
                <dsig:XPath xmlns:samlp_xpath="urn:oasis:names:tc:SAML:1.0:protocol">
                  count(ancestor-or-self::samlp_xpath:Response |
                  here()/ancestor::samlp_xpath:Response[1]) =
                  count(ancestor-or-self::samlp_xpath:Response)
                </dsig:XPath>
              </dsig:Transform>
            </dsig:Transforms>
            <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
            <dsig:DigestValue>t1nvDq1bZXEhBIXc/DHcqIrjRyI=</dsig:DigestValue>
          </dsig:Reference>
        </dsig:SignedInfo>
        <dsig:SignatureValue>PipZFFmmYcSnSU9p5AcOmFbRYoeatERYPy4IRk+jU26xk9sAM6yfhXtbK8csl/0w
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        <dsig:KeyInfo>
          <dsig:X509Data>
    <X509Certificate xmlns="http://www.w3.org/2000/09/xmldsig#">MIIE3zCCBEigAwIBAgIBBTANBgkqhkiG9w0BAQQFADCByzELMAkGA1UEBhMCVVMx
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    NJ2D</X509Certificate>
    </dsig:X509Data>
        </dsig:KeyInfo>
      </dsig:Signature>
      <Status>
        <StatusCode Value="samlp:Success"/>
      </Status>
      <Assertion xmlns="urn:oasis:names:tc:SAML:1.0:assertion" AssertionID="7ddc31-ed4a03d735-FB24AD27D96135B68C99FB9AACFE2FFC" IssueInstant="2002-04-18T16:56:54Z" Issuer="hs.osu.edu" MajorVersion="1" MinorVersion="0">
        <Conditions NotBefore="2002-04-18T16:56:54Z" NotOnOrAfter="2002-04-18T17:01:54Z">
          <AudienceRestrictionCondition>
            <Audience>http://middleware.internet2.edu/shibboleth/clubs/clubshib/1.0/</Audience>
          </AudienceRestrictionCondition>
        </Conditions>
        <AuthenticationStatement AuthenticationInstant="2002-04-18T16:56:53Z" AuthenticationMethod="urn:mace:shibboleth:authmethod">
          <Subject>
            <NameIdentifier Format="urn:mace:shibboleth:1.0:handle" NameQualifier="osu.edu">foo</NameIdentifier>
            <SubjectConfirmation>
              <ConfirmationMethod>urn:oasis:names:tc:SAML:1.0:cm:Bearer</ConfirmationMethod>
            </SubjectConfirmation>
          </Subject>
          <SubjectLocality IPAddress="127.0.0.1"/>
          <AuthorityBinding AuthorityKind="samlp:AttributeQuery" Binding="urn:oasis:names:tc:SAML:1.0:bindings:SOAP-binding" Location="https://aa.osu.edu/"/>
        </AuthenticationStatement>
      </Assertion>
    </Response>