xmlsecurity: improve handling of multiple X509Data elements

Combine everything related to a certificate in a new struct X509Data.

The CertDigest is not actually written in the X509Data element but in
xades:Cert, so try to find the matching entry in
XSecController::setX509CertDigest().

There was a confusing interaction with PGP signatures, where ouGpgKeyID
was used for import, but export wrote the value from ouCertDigest
instead - this needed fixing.

The main point of this is enforcing a constraint from xmldsig-core 4.5.4:

  All certificates appearing in an X509Data element MUST relate to the
  validation key by either containing it or being part of a certification
  chain that terminates in a certificate containing the validation key.

Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111254
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit 9e82509b09f5fe2eb77bcdb8fd193c71923abb67)

xmlsecurity: improve handling of multiple certificates per X509Data

It turns out that an X509Data element can contain an arbitrary number of
each of its child elements.

How exactly certificates of an issuer chain may or should be distributed
across multiple X509Data elements isn't terribly obvious.

One thing that is clear is that any element that refers to or contains
one particular certificate has to be a child of the same X509Data
element, although in no particular order, so try to match the 2 such
elements that the parser supports in XSecController::setX509Data().

Presumably the only way it makes sense to have multiple signing
certificates is if they all contain the same key but are signed by
different CAs. This case isn't handled currently; CheckX509Data() will
complain there's not a single chain and validation of the certificates
will fail.

Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111500
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit 5af5ea893bcb8a8eb472ac11133da10e5a604e66)

xmlsecurity: add EqualDistinguishedNames()

Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111545
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit 1d3da3486d827dd5e7a3bf1c7a533f5aa9860e42)

xmlsecurity: avoid exception in DigitalSignaturesDialog::getCertificate()

Fallback to PGP if there's no X509 signing certificate because
CheckX509Data() failed prevents the dialog from popping up.

To avoid confusing the user in this situation, the dialog should
show no certificate, which is already the case.

Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111664
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit 90b725675c2964f4a151d802d9afedd8bc2ae1a7)

xmlsecurity: fix crash in DocumentDigitalSignatures::isAuthorTrusted()

If the argument is null.

This function also should use EqualDistinguishedNames().

Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111667
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit ca98e505cd69bf95d8ddb9387cf3f8e03ae4577d)

Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111910
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit a1cf770c2d7ca3e153e0b1f01ddcc313bc2bed7f)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/113058
Tested-by: Michael Stahl <michael.stahl@allotropia.de>
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>

(cherry picked from commit 8558bc8a0702bf41e020018f469b9feccd99f92d)

Conflicts:
	include/svl/sigstruct.hxx
	xmlsecurity/inc/xmlsignaturehelper.hxx
	xmlsecurity/source/helper/pdfsignaturehelper.cxx
	xmlsecurity/source/helper/xsecparser.cxx
	xmlsecurity/source/helper/xsecsign.cxx
	xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
	xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx
	xmlsecurity/source/xmlsec/nss/xmlsignature_nssimpl.cxx

(cherry picked from commit ed914263f07acabcea8681418d9d277d62e22ed5)

Conflicts:
	include/svl/sigstruct.hxx
	svl/source/crypto/cryptosign.cxx
	sw/source/core/edit/edfcol.cxx
	xmlsecurity/inc/xsecctl.hxx
	xmlsecurity/source/component/documentdigitalsignatures.cxx
	xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx
	xmlsecurity/source/helper/xmlsignaturehelper.cxx
	xmlsecurity/source/helper/xsecctl.cxx
	xmlsecurity/source/helper/xsecverify.cxx
	xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
	xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx

Change-Id: I9633a980b0c18d58dfce24fc59396a833498a77d

21 files changed, 699 insertions, 221 deletions

diff --git a/xmlsecurity/inc/biginteger.hxx b/xmlsecurity/inc/biginteger.hxx
index 2cd116d50763..b4bd3be07f7c 100644
--- a/xmlsecurity/inc/biginteger.hxx
+++ b/xmlsecurity/inc/biginteger.hxx
@@ -31,6 +31,9 @@ namespace xmlsecurity
 {
 XSECXMLSEC_DLLPUBLIC OUString bigIntegerToNumericString( const css::uno::Sequence< sal_Int8 >& serial );
 XSECXMLSEC_DLLPUBLIC css::uno::Sequence< sal_Int8 > numericStringToBigInteger ( const OUString& serialNumber );
+
+XSECXMLSEC_DLLPUBLIC bool EqualDistinguishedNames(OUString const& rName1,
+                                                  OUString const& rName2);
 }
 
 #endif
diff --git a/xmlsecurity/inc/sigstruct.hxx b/xmlsecurity/inc/sigstruct.hxx
index 2b52dc3c0af0..d3f8ef2c68e6 100644
--- a/xmlsecurity/inc/sigstruct.hxx
+++ b/xmlsecurity/inc/sigstruct.hxx
@@ -72,9 +72,30 @@ struct SignatureInformation
     sal_Int32 nSecurityId;
     css::xml::crypto::SecurityOperationStatus nStatus;
     SignatureReferenceInformations  vSignatureReferenceInfors;
-    OUString ouX509IssuerName;
-    OUString ouX509SerialNumber;
-    OUString ouX509Certificate;
+    struct X509CertInfo
+    {
+        OUString X509IssuerName;
+        OUString X509SerialNumber;
+        OUString X509Certificate;
+        /// OOXML certificate SHA-256 digest, empty for ODF except when doing XAdES signature.
+        OUString CertDigest;
+        /// The certificate owner (aka subject).
+        OUString X509Subject;
+    };
+    typedef std::vector<X509CertInfo> X509Data;
+    // note: at parse time, it's unkown which one is the signing certificate;
+    // ImplVerifySignatures() figures it out and puts it at the back
+    std::vector<X509Data> X509Datas;
+
+    X509CertInfo const* GetSigningCertificate() const
+    {
+        if (X509Datas.empty())
+        {
+            return nullptr;
+        }
+        assert(!X509Datas.back().empty());
+        return & X509Datas.back().back();
+    }
 
     OUString ouGpgKeyID;
     OUString ouGpgCertificate;
@@ -101,14 +122,13 @@ struct SignatureInformation
     //and the converted time is written back, then the string looks different
     //and the signature is broken.
     OUString ouDateTime;
-
+    /// The Id attribute of the <SignatureProperty> element that contains the <dc:date>.
     OUString ouDateTimePropertyId;
     /// Characters of the <dc:description> element inside the signature.
     OUString ouDescription;
     /// The Id attribute of the <SignatureProperty> element that contains the <dc:description>.
     OUString ouDescriptionPropertyId;
-    /// OOXML certificate SHA-256 digest, empty for ODF except when doing XAdES signature.
-    OUString ouCertDigest;
+
     /// A full OOXML signature for unchanged roundtrip, empty for ODF.
     css::uno::Sequence<sal_Int8> aSignatureBytes;
     /// For PDF: digest format, from css::xml::crypto::DigestID
diff --git a/xmlsecurity/inc/xmlsignaturehelper.hxx b/xmlsecurity/inc/xmlsignaturehelper.hxx
index a473b1efd840..6c10108dccdd 100644
--- a/xmlsecurity/inc/xmlsignaturehelper.hxx
+++ b/xmlsecurity/inc/xmlsignaturehelper.hxx
@@ -36,6 +36,11 @@
 #include <com/sun/star/xml/crypto/sax/XSignatureCreationResultListener.hpp>
 #include <com/sun/star/xml/crypto/sax/XSignatureVerifyResultListener.hpp>
 
+#include <com/sun/star/security/XCertificate.hpp>
+#include <com/sun/star/xml/crypto/XSecurityEnvironment.hpp>
+
+
+class DateTime;
 class Date;
 namespace tools { class Time; }
 
@@ -126,6 +131,15 @@ public:
                 // After signing/verifying, get information about signatures
     SignatureInformation  GetSignatureInformation( sal_Int32 nSecurityId ) const;
     SignatureInformations GetSignatureInformations() const;
+    /// ImplVerifySignature calls this to figure out which X509Data is the
+    /// signing certificate and update the internal state with the result.
+    /// @return
+    ///    A sequence with the signing certificate at the back on success.
+    ///    An empty sequence on failure.
+    std::vector<css::uno::Reference<css::security::XCertificate>>
+    CheckAndUpdateSignatureInformation(
+        css::uno::Reference<css::xml::crypto::XSecurityEnvironment> const& xSecEnv,
+        SignatureInformation const& rInfo);
 
                 // See XSecController for documentation
     void        StartMission(const css::uno::Reference<css::xml::crypto::XXMLSecurityContext>& xSecurityContext);
diff --git a/xmlsecurity/inc/xsecctl.hxx b/xmlsecurity/inc/xsecctl.hxx
index 8c6e916f1d31..b510afa60fa8 100644
--- a/xmlsecurity/inc/xsecctl.hxx
+++ b/xmlsecurity/inc/xsecctl.hxx
@@ -303,18 +303,21 @@ private:
         sal_Int32 nDigestID );
     void setReferenceCount() const;
 
-    void setX509IssuerName( OUString& ouX509IssuerName );
-    void setX509SerialNumber( OUString& ouX509SerialNumber );
-    void setX509Certificate( OUString& ouX509Certificate );
-    void setSignatureValue( OUString& ouSignatureValue );
-    void setDigestValue( sal_Int32 nDigestID, OUString& ouDigestValue );
-    void setGpgKeyID( OUString& ouKeyID );
-    void setGpgCertificate( OUString& ouGpgCert );
-    void setGpgOwner( OUString& ouGpgOwner );
+    void setX509Data(
+        std::vector<std::pair<OUString, OUString>> & rX509IssuerSerials,
+        std::vector<OUString> const& rX509Certificates);
+    void setX509CertDigest(
+        OUString const& rCertDigest, sal_Int32 const nReferenceDigestID,
+        OUString const& rX509IssuerName, OUString const& rX509SerialNumber);
+
+    void setSignatureValue( OUString const & ouSignatureValue );
+    void setDigestValue( sal_Int32 nDigestID, OUString const & ouDigestValue );
+    void setGpgKeyID( OUString const & ouKeyID );
+    void setGpgCertificate( OUString const & ouGpgCert );
+    void setGpgOwner( OUString const & ouGpgOwner );
 
     void setDate(OUString const& rId, OUString const& ouDate);
     void setDescription(OUString const& rId, OUString const& rDescription);
-    void setCertDigest(const OUString& rCertDigest);
 
 public:
     void setSignatureBytes(const css::uno::Sequence<sal_Int8>& rBytes);
@@ -347,6 +350,10 @@ public:
     SignatureInformation    getSignatureInformation( sal_Int32 nSecurityId ) const;
     SignatureInformations   getSignatureInformations() const;
 
+    /// only verify can figure out which X509Data is the signing certificate
+    void UpdateSignatureInformation(sal_Int32 nSecurityId,
+            std::vector<SignatureInformation::X509Data> const& rDatas);
+
     static void exportSignature(
         const css::uno::Reference< css::xml::sax::XDocumentHandler >& xDocumentHandler,
         const SignatureInformation& signatureInfo,
diff --git a/xmlsecurity/source/component/documentdigitalsignatures.cxx b/xmlsecurity/source/component/documentdigitalsignatures.cxx
index 6f235fd550ac..17b6c4ca4b08 100644
--- a/xmlsecurity/source/component/documentdigitalsignatures.cxx
+++ b/xmlsecurity/source/component/documentdigitalsignatures.cxx
@@ -43,6 +43,7 @@
 #include <unotools/securityoptions.hxx>
 #include <com/sun/star/security/CertificateValidity.hpp>
 #include <comphelper/documentconstants.hxx>
+#include <comphelper/sequence.hxx>
 #include <cppuhelper/supportsservice.hxx>
 #include <com/sun/star/lang/IllegalArgumentException.hpp>
 
@@ -327,31 +328,36 @@ DocumentDigitalSignatures::ImplVerifySignatures(
             const SignatureInformation& rInfo = aSignInfos[n];
             css::security::DocumentSignatureInformation& rSigInfo = arInfos[n];
 
-            if (rInfo.ouGpgCertificate.isEmpty()) // X.509
+            if (!rInfo.X509Datas.empty()) // X.509
             {
-                if (!rInfo.ouX509Certificate.isEmpty())
-                    rSigInfo.Signer = xSecEnv->createCertificateFromAscii( rInfo.ouX509Certificate ) ;
-                if (!rSigInfo.Signer.is())
-                    rSigInfo.Signer = xSecEnv->getCertificate( rInfo.ouX509IssuerName,
-                                                               xmlsecurity::numericStringToBigInteger( rInfo.ouX509SerialNumber ) );
-
-                // Verify certificate
-                //We have patched our version of libxmlsec, so that it does not verify the certificates. This has two
-                //reasons. First we want two separate status for signature and certificate. Second libxmlsec calls
-                //CERT_VerifyCertificate (Solaris, Linux) falsely, so that it always regards the certificate as valid.
-                //On Windows the checking of the certificate path is buggy. It does name matching (issuer, subject name)
-                //to find the parent certificate. It does not take into account that there can be several certificates
-                //with the same subject name.
-
-                try {
-                    rSigInfo.CertificateStatus = xSecEnv->verifyCertificate(rSigInfo.Signer,
-                                                                            Sequence<Reference<css::security::XCertificate> >());
-                } catch (SecurityException& ) {
-                    OSL_FAIL("Verification of certificate failed");
+                std::vector<uno::Reference<security::XCertificate>> certs(
+                    rSignatureHelper.CheckAndUpdateSignatureInformation(
+                        xSecEnv, rInfo));
+                if (certs.empty())
+                {
                     rSigInfo.CertificateStatus = css::security::CertificateValidity::INVALID;
                 }
+                else
+                {
+                    rSigInfo.Signer = certs.back();
+                    // get only intermediates
+                    certs.pop_back();
+                // On Windows checking the certificate path is buggy. It does name matching (issuer, subject name)
+                // to find the parent certificate. It does not take into account that there can be several certificates
+                // with the same subject name.
+                    try
+                    {
+                        rSigInfo.CertificateStatus = xSecEnv->verifyCertificate(
+                            rSigInfo.Signer, comphelper::containerToSequence(certs));
+                    }
+                    catch (SecurityException&)
+                    {
+                        SAL_WARN("xmlsecurity.comp", "Verification of certificate failed");
+                        rSigInfo.CertificateStatus = css::security::CertificateValidity::INVALID;
+                    }
+                }
             }
-            else // GPG
+            else if (!rInfo.ouGpgCertificate.isEmpty() && xGpgSecEnv.is()) // GPG
             {
                 // TODO not ideal to retrieve cert by keyID, might
                 // collide, or PGPKeyID format might change - can't we
@@ -429,11 +435,15 @@ void DocumentDigitalSignatures::showCertificate(
 }
 
 sal_Bool DocumentDigitalSignatures::isAuthorTrusted(
-    const Reference< css::security::XCertificate >& Author )
+    const Reference<css::security::XCertificate>& xAuthor)
 {
+    if (!xAuthor.is())
+    {
+        return false;
+    }
     bool bFound = false;
 
-    OUString sSerialNum = xmlsecurity::bigIntegerToNumericString( Author->getSerialNumber() );
+    OUString sSerialNum = xmlsecurity::bigIntegerToNumericString(xAuthor->getSerialNumber());
 
     Sequence< SvtSecurityOptions::Certificate > aTrustedAuthors = SvtSecurityOptions().GetTrustedAuthors();
     const SvtSecurityOptions::Certificate* pAuthors = aTrustedAuthors.getConstArray();
@@ -441,7 +451,8 @@ sal_Bool DocumentDigitalSignatures::isAuthorTrusted(
     for ( ; pAuthors != pAuthorsEnd; ++pAuthors )
     {
         SvtSecurityOptions::Certificate aAuthor = *pAuthors;
-        if ( ( aAuthor[0] == Author->getIssuerName() ) && ( aAuthor[1] == sSerialNum ) )
+        if (xmlsecurity::EqualDistinguishedNames(aAuthor[0], xAuthor->getIssuerName())
+            && (aAuthor[1] == sSerialNum))
         {
             bFound = true;
             break;
diff --git a/xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx b/xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx
index 5a49151608d3..4fb076966a30 100644
--- a/xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx
+++ b/xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx
@@ -575,7 +575,7 @@ void DigitalSignaturesDialog::ImplFillSignaturesBox()
                 if (!rInfo.ouGpgCertificate.isEmpty())
                     aType = "OpenPGP";
                 // XML based: XAdES or not.
-                else if (!rInfo.ouCertDigest.isEmpty())
+                else if (rInfo.GetSigningCertificate() && !rInfo.GetSigningCertificate()->CertDigest.isEmpty())
                     aType = "XAdES";
                 else
                     aType = "XML-DSig";
@@ -674,8 +674,8 @@ uno::Reference<security::XCertificate> DigitalSignaturesDialog::getCertificate(c
     uno::Reference<security::XCertificate> xCert;
 
     //First we try to get the certificate which is embedded in the XML Signature
-    if (!rInfo.ouX509Certificate.isEmpty())
-        xCert = xSecEnv->createCertificateFromAscii(rInfo.ouX509Certificate);
+    if (xSecEnv.is() && rInfo.GetSigningCertificate() && !rInfo.GetSigningCertificate()->X509Certificate.isEmpty())
+        xCert = xSecEnv->createCertificateFromAscii(rInfo.GetSigningCertificate()->X509Certificate);
     else {
         //There must be an embedded certificate because we use it to get the
         //issuer name. We cannot use /Signature/KeyInfo/X509Data/X509IssuerName
@@ -687,9 +687,13 @@ uno::Reference<security::XCertificate> DigitalSignaturesDialog::getCertificate(c
     }
 
     //In case there is no embedded certificate we try to get it from a local store
-    if (!xCert.is())
-        xCert = xSecEnv->getCertificate( rInfo.ouX509IssuerName, xmlsecurity::numericStringToBigInteger( rInfo.ouX509SerialNumber ) );
-    if (!xCert.is())
+
+    if (!xCert.is() && xSecEnv.is() && rInfo.GetSigningCertificate())
+    {
+        xCert = xSecEnv->getCertificate(rInfo.GetSigningCertificate()->X509IssuerName,
+            xmlsecurity::numericStringToBigInteger(rInfo.GetSigningCertificate()->X509SerialNumber));
+    }
+    if (!xCert.is() && xGpgSecEnv.is() && !rInfo.ouGpgKeyID.isEmpty())
         xCert = xGpgSecEnv->getCertificate( rInfo.ouGpgKeyID, xmlsecurity::numericStringToBigInteger("") );
 
     SAL_WARN_IF( !xCert.is(), "xmlsecurity.dialogs", "Certificate not found and can't be created!" );
diff --git a/xmlsecurity/source/helper/documentsignaturehelper.cxx b/xmlsecurity/source/helper/documentsignaturehelper.cxx
index 9a2537ee828d..f4baae9fa7b5 100644
--- a/xmlsecurity/source/helper/documentsignaturehelper.cxx
+++ b/xmlsecurity/source/helper/documentsignaturehelper.cxx
@@ -552,6 +552,29 @@ void DocumentSignatureHelper::writeDigestMethod(
     xDocumentHandler->endElement("DigestMethod");
 }
 
+static void WriteXadesCert(
+    uno::Reference<xml::sax::XDocumentHandler> const& xDocumentHandler,
+    SignatureInformation::X509CertInfo const& rCertInfo)
+{
+    xDocumentHandler->startElement("xd:Cert", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+    xDocumentHandler->startElement("xd:CertDigest", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+    DocumentSignatureHelper::writeDigestMethod(xDocumentHandler);
+    xDocumentHandler->startElement("DigestValue", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+    assert(!rCertInfo.CertDigest.isEmpty());
+    xDocumentHandler->characters(rCertInfo.CertDigest);
+    xDocumentHandler->endElement("DigestValue");
+    xDocumentHandler->endElement("xd:CertDigest");
+    xDocumentHandler->startElement("xd:IssuerSerial", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+    xDocumentHandler->startElement("X509IssuerName", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+    xDocumentHandler->characters(rCertInfo.X509IssuerName);
+    xDocumentHandler->endElement("X509IssuerName");
+    xDocumentHandler->startElement("X509SerialNumber", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+    xDocumentHandler->characters(rCertInfo.X509SerialNumber);
+    xDocumentHandler->endElement("X509SerialNumber");
+    xDocumentHandler->endElement("xd:IssuerSerial");
+    xDocumentHandler->endElement("xd:Cert");
+}
+
 void DocumentSignatureHelper::writeSignedProperties(
     const uno::Reference<xml::sax::XDocumentHandler>& xDocumentHandler,
     const SignatureInformation& signatureInfo,
@@ -568,26 +591,26 @@ void DocumentSignatureHelper::writeSignedProperties(
     xDocumentHandler->characters(sDate);
     xDocumentHandler->endElement("xd:SigningTime");
     xDocumentHandler->startElement("xd:SigningCertificate", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    xDocumentHandler->startElement("xd:Cert", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    xDocumentHandler->startElement("xd:CertDigest", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    writeDigestMethod(xDocumentHandler);
-
-    xDocumentHandler->startElement("DigestValue", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    // TODO: this is empty for gpg signatures currently
-    //assert(!signatureInfo.ouCertDigest.isEmpty());
-    xDocumentHandler->characters(signatureInfo.ouCertDigest);
-    xDocumentHandler->endElement("DigestValue");
-
-    xDocumentHandler->endElement("xd:CertDigest");
-    xDocumentHandler->startElement("xd:IssuerSerial", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    xDocumentHandler->startElement("X509IssuerName", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    xDocumentHandler->characters(signatureInfo.ouX509IssuerName);
-    xDocumentHandler->endElement("X509IssuerName");
-    xDocumentHandler->startElement("X509SerialNumber", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    xDocumentHandler->characters(signatureInfo.ouX509SerialNumber);
-    xDocumentHandler->endElement("X509SerialNumber");
-    xDocumentHandler->endElement("xd:IssuerSerial");
-    xDocumentHandler->endElement("xd:Cert");
+    assert(signatureInfo.GetSigningCertificate() || !signatureInfo.ouGpgKeyID.isEmpty());
+    if (signatureInfo.GetSigningCertificate())
+    {
+        // how should this deal with multiple X509Data elements?
+        // for now, let's write all of the certificates ...
+        for (auto const& rData : signatureInfo.X509Datas)
+        {
+            for (auto const& it : rData)
+            {
+                WriteXadesCert(xDocumentHandler, it);
+            }
+        }
+    }
+    else
+    {
+        // for PGP, write empty mandatory X509IssuerName, X509SerialNumber
+        SignatureInformation::X509CertInfo temp;
+        temp.CertDigest = signatureInfo.ouGpgKeyID;
+        WriteXadesCert(xDocumentHandler, temp);
+    }
     xDocumentHandler->endElement("xd:SigningCertificate");
     xDocumentHandler->startElement("xd:SignaturePolicyIdentifier", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
     xDocumentHandler->startElement("xd:SignaturePolicyImplied", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
diff --git a/xmlsecurity/source/helper/documentsignaturemanager.cxx b/xmlsecurity/source/helper/documentsignaturemanager.cxx
index 4718555d54c2..fa1ca7915d88 100644
--- a/xmlsecurity/source/helper/documentsignaturemanager.cxx
+++ b/xmlsecurity/source/helper/documentsignaturemanager.cxx
@@ -496,6 +496,18 @@ void DocumentSignatureManager::read(bool bUseTempStream, bool bCacheLastSignatur
             maSignatureHelper.ReadAndVerifySignatureStorage(aStreamHelper.xSignatureStorage, bCacheLastSignature);
         maSignatureHelper.EndMission();
 
+        // this parses the XML independently from ImplVerifySignatures() - check
+        // certificates here too ...
+        for (auto const& it : maSignatureHelper.GetSignatureInformations())
+        {
+            if (!it.X509Datas.empty())
+            {
+                uno::Reference<xml::crypto::XSecurityEnvironment> const xSecEnv(
+                    getSecurityEnvironment());
+                maSignatureHelper.CheckAndUpdateSignatureInformation(xSecEnv, it);
+            }
+        }
+
         maCurrentSignatureInformations = maSignatureHelper.GetSignatureInformations();
     }
     else
diff --git a/xmlsecurity/source/helper/ooxmlsecexporter.cxx b/xmlsecurity/source/helper/ooxmlsecexporter.cxx
index 336ab565c2eb..3d2f278feb94 100644
--- a/xmlsecurity/source/helper/ooxmlsecexporter.cxx
+++ b/xmlsecurity/source/helper/ooxmlsecexporter.cxx
@@ -183,13 +183,21 @@ void OOXMLSecExporter::Impl::writeKeyInfo()
 {
     m_xDocumentHandler->startElement(
         "KeyInfo", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    m_xDocumentHandler->startElement(
-        "X509Data", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    m_xDocumentHandler->startElement(
-        "X509Certificate", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
-    m_xDocumentHandler->characters(m_rInformation.ouX509Certificate);
-    m_xDocumentHandler->endElement("X509Certificate");
-    m_xDocumentHandler->endElement("X509Data");
+    assert(m_rInformation.GetSigningCertificate());
+    for (auto const& rData : m_rInformation.X509Datas)
+    {
+        m_xDocumentHandler->startElement(
+            "X509Data", uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+        for (auto const& it : rData)
+        {
+            m_xDocumentHandler->startElement(
+                "X509Certificate",
+                uno::Reference<xml::sax::XAttributeList>(new SvXMLAttributeList()));
+            m_xDocumentHandler->characters(it.X509Certificate);
+            m_xDocumentHandler->endElement("X509Certificate");
+        }
+        m_xDocumentHandler->endElement("X509Data");
+    }
     m_xDocumentHandler->endElement("KeyInfo");
 }
 
diff --git a/xmlsecurity/source/helper/ooxmlsecparser.cxx b/xmlsecurity/source/helper/ooxmlsecparser.cxx
index 95d9d4767167..4181a207481b 100644
--- a/xmlsecurity/source/helper/ooxmlsecparser.cxx
+++ b/xmlsecurity/source/helper/ooxmlsecparser.cxx
@@ -146,9 +146,22 @@ void SAL_CALL OOXMLSecParser::endElement(const OUString& rName)
         m_pXSecController->setSignatureValue(m_aSignatureValue);
         m_bInSignatureValue = false;
     }
+    else if (rName == "X509Data")
+    {
+        std::vector<std::pair<OUString, OUString>> X509IssuerSerials;
+        std::vector<OUString> X509Certificates;
+        if (!m_aX509Certificate.isEmpty())
+        {
+            X509Certificates.emplace_back(m_aX509Certificate);
+        }
+        if (!m_aX509IssuerName.isEmpty() && !m_aX509SerialNumber.isEmpty())
+        {
+            X509IssuerSerials.emplace_back(m_aX509IssuerName, m_aX509SerialNumber);
+        }
+        m_pXSecController->setX509Data(X509IssuerSerials, X509Certificates);
+    }
     else if (rName == "X509Certificate")
     {
-        m_pXSecController->setX509Certificate(m_aX509Certificate);
         m_bInX509Certificate = false;
     }
     else if (rName == "mdssi:Value")
@@ -163,17 +176,18 @@ void SAL_CALL OOXMLSecParser::endElement(const OUString& rName)
     }
     else if (rName == "X509IssuerName")
     {
-        m_pXSecController->setX509IssuerName(m_aX509IssuerName);
         m_bInX509IssuerName = false;
     }
     else if (rName == "X509SerialNumber")
     {
-        m_pXSecController->setX509SerialNumber(m_aX509SerialNumber);
         m_bInX509SerialNumber = false;
     }
+    else if (rName == "xd:Cert")
+    {
+        m_pXSecController->setX509CertDigest(m_aCertDigest, css::xml::crypto::DigestID::SHA1, m_aX509IssuerName, m_aX509SerialNumber);
+    }
     else if (rName == "xd:CertDigest")
     {
-        m_pXSecController->setCertDigest(m_aCertDigest);
         m_bInCertDigest = false;
     }
 
diff --git a/xmlsecurity/source/helper/pdfsignaturehelper.cxx b/xmlsecurity/source/helper/pdfsignaturehelper.cxx
index 9bb6e59d0380..ef78b8dc8a99 100644
--- a/xmlsecurity/source/helper/pdfsignaturehelper.cxx
+++ b/xmlsecurity/source/helper/pdfsignaturehelper.cxx
@@ -76,8 +76,12 @@ uno::Sequence<security::DocumentSignatureInformation> PDFSignatureHelper::GetDoc
         const SignatureInformation& rInternal = m_aSignatureInfos[i];
         security::DocumentSignatureInformation& rExternal = aRet[i];
         rExternal.SignatureIsValid = rInternal.nStatus == xml::crypto::SecurityOperationStatus_OPERATION_SUCCEEDED;
-        if (!rInternal.ouX509Certificate.isEmpty())
-            rExternal.Signer = xSecEnv->createCertificateFromAscii(rInternal.ouX509Certificate);
+        if (rInternal.GetSigningCertificate()
+            && !rInternal.GetSigningCertificate()->X509Certificate.isEmpty())
+        {
+            rExternal.Signer = xSecEnv->createCertificateFromAscii(
+                rInternal.GetSigningCertificate()->X509Certificate);
+        }
         rExternal.PartialDocumentSignature = rInternal.bPartialDocumentSignature;
 
         // Verify certificate.
diff --git a/xmlsecurity/source/helper/xmlsignaturehelper.cxx b/xmlsecurity/source/helper/xmlsignaturehelper.cxx
index 8cd1afd6e795..0986ac0dbbc2 100644
--- a/xmlsecurity/source/helper/xmlsignaturehelper.cxx
+++ b/xmlsecurity/source/helper/xmlsignaturehelper.cxx
@@ -21,6 +21,7 @@
 #include <xmlsignaturehelper.hxx>
 #include <documentsignaturehelper.hxx>
 #include "xsecctl.hxx"
+#include <biginteger.hxx>
 
 #include "xmlsignaturehelper2.hxx"
 
@@ -49,6 +50,8 @@
 #include <comphelper/ofopxmlhelper.hxx>
 #include <comphelper/sequence.hxx>
 
+#include <boost/optional.hpp>
+
 #define NS_DOCUMENTSIGNATURES   "http://openoffice.org/2004/documentsignatures"
 #define NS_DOCUMENTSIGNATURES_ODF_1_2 "urn:oasis:names:tc:opendocument:xmlns:digitalsignature:1.0"
 #define OOXML_SIGNATURE_ORIGIN "http://schemas.openxmlformats.org/package/2006/relationships/digital-signature/origin"
@@ -576,4 +579,162 @@ bool XMLSignatureHelper::CreateAndWriteOOXMLSignature(const uno::Reference<embed
     return !mbError;
 }
 
+/** check this constraint from xmldsig-core 4.5.4:
+
+  All certificates appearing in an X509Data element MUST relate to the
+  validation key by either containing it or being part of a certification
+  chain that terminates in a certificate containing the validation key.
+ */
+static auto CheckX509Data(
+    uno::Reference<xml::crypto::XSecurityEnvironment> const& xSecEnv,
+    std::vector<SignatureInformation::X509CertInfo> const& rX509CertInfos,
+    std::vector<uno::Reference<security::XCertificate>> & rCerts,
+    std::vector<SignatureInformation::X509CertInfo> & rSorted) -> bool
+{
+    assert(rCerts.empty());
+    assert(rSorted.empty());
+    if (rX509CertInfos.empty())
+    {
+        SAL_WARN("xmlsecurity.comp", "no X509Data");
+        return false;
+    }
+    std::vector<uno::Reference<security::XCertificate>> certs;
+    for (SignatureInformation::X509CertInfo const& it : rX509CertInfos)
+    {
+        if (!it.X509Certificate.isEmpty())
+        {
+            certs.emplace_back(xSecEnv->createCertificateFromAscii(it.X509Certificate));
+        }
+        else
+        {
+            certs.emplace_back(xSecEnv->getCertificate(
+                it.X509IssuerName,
+                xmlsecurity::numericStringToBigInteger(it.X509SerialNumber)));
+        }
+        if (!certs.back().is())
+        {
+            SAL_WARN("xmlsecurity.comp", "X509Data cannot be parsed");
+            return false;
+        }
+    }
+
+    // first, search one whose issuer isn't in the list, or a self-signed one
+    boost::optional<size_t> start;
+    for (size_t i = 0; i < certs.size(); ++i)
+    {
+        for (size_t j = 0; ; ++j)
+        {
+            if (j == certs.size())
+            {
+                if (start)
+                {
+                    SAL_WARN("xmlsecurity.comp", "X509Data do not form a chain: certificate has no issuer but already have start of chain: " << certs[i]->getSubjectName());
+                    return false;
+                }
+                start = i; // issuer isn't in the list
+                break;
+            }
+            if (xmlsecurity::EqualDistinguishedNames(certs[i]->getIssuerName(), certs[j]->getSubjectName()))
+            {
+                if (i == j) // self signed
+                {
+                    if (start)
+                    {
+                        SAL_WARN("xmlsecurity.comp", "X509Data do not form a chain: certificate is self-signed but already have start of chain: " << certs[i]->getSubjectName());
+                        return false;
+                    }
+                    start = i;
+                }
+                break;
+            }
+        }
+    }
+    std::vector<size_t> chain;
+    if (!start)
+    {
+        // this can only be a cycle?
+        SAL_WARN("xmlsecurity.comp", "X509Data do not form a chain: cycle detected");
+        return false;
+    }
+    chain.emplace_back(*start);
+
+    // second, check that there is a chain, no tree or cycle...
+    for (size_t i = 0; i < certs.size(); ++i)
+    {
+        assert(chain.size() == i + 1);
+        for (size_t j = 0; j < certs.size(); ++j)
+        {
+            if (chain[i] != j)
+            {
+                if (xmlsecurity::EqualDistinguishedNames(
+                        certs[chain[i]]->getSubjectName(), certs[j]->getIssuerName()))
+                {
+                    if (chain.size() != i + 1) // already found issuee?
+                    {
+                        SAL_WARN("xmlsecurity.comp", "X509Data do not form a chain: certificate issued 2 others: " << certs[chain[i]]->getSubjectName());
+                        return false;
+                    }
+                    chain.emplace_back(j);
+                }
+            }
+        }
+        if (i == certs.size() - 1)
+        {   // last one: must be a leaf
+            if (chain.size() != i + 1)
+            {
+                SAL_WARN("xmlsecurity.comp", "X509Data do not form a chain: certificate in cycle: " << certs[chain[i]]->getSubjectName());
+                return false;
+            }
+        }
+        else if (chain.size() != i + 2)
+        {   // not issuer of another?
+            SAL_WARN("xmlsecurity.comp", "X509Data do not form a chain: certificate issued 0 others: " << certs[chain[i]]->getSubjectName());
+            return false;
+        }
+    }
+
+    // success
+    assert(chain.size() == rX509CertInfos.size());
+    for (auto const& it : chain)
+    {
+        rSorted.emplace_back(rX509CertInfos[it]);
+        rCerts.emplace_back(certs[it]);
+    }
+    return true;
+}
+
+std::vector<uno::Reference<security::XCertificate>>
+XMLSignatureHelper::CheckAndUpdateSignatureInformation(
+    uno::Reference<xml::crypto::XSecurityEnvironment> const& xSecEnv,
+    SignatureInformation const& rInfo)
+{
+    // if the check fails, it's not possible to determine which X509Data
+    // contained the signing certificate - the UI cannot display something
+    // useful in this case, so prevent anything misleading by clearing the
+    // X509Datas.
+
+    std::vector<uno::Reference<security::XCertificate>> certs;
+    std::vector<SignatureInformation::X509Data> datas;
+    // TODO: for now, just merge all X509Datas together for checking...
+    // (this will probably break round-trip of signature with multiple X509Data,
+    // no idea if that is a problem)
+    SignatureInformation::X509Data temp;
+    SignatureInformation::X509Data tempResult;
+    for (auto const& rData : rInfo.X509Datas)
+    {
+        for (auto const& it : rData)
+        {
+            temp.emplace_back(it);
+        }
+    }
+    if (CheckX509Data(xSecEnv, temp, certs, tempResult))
+    {
+        datas.emplace_back(tempResult);
+    }
+
+    // rInfo is a copy, update the original
+    mpXSecController->UpdateSignatureInformation(rInfo.nSecurityId, datas);
+    return certs;
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/xmlsecurity/source/helper/xsecctl.cxx b/xmlsecurity/source/helper/xsecctl.cxx
index ee5ec75c28fe..2d7bdfe3d7e6 100644
--- a/xmlsecurity/source/helper/xsecctl.cxx
+++ b/xmlsecurity/source/helper/xsecctl.cxx
@@ -738,7 +738,7 @@ void XSecController::exportSignature(
                     xDocumentHandler->startElement(
                         "PGPKeyID",
                         cssu::Reference< cssxs::XAttributeList > (new SvXMLAttributeList()));
-                    xDocumentHandler->characters( signatureInfo.ouCertDigest );
+                    xDocumentHandler->characters(signatureInfo.ouGpgKeyID);
                     xDocumentHandler->endElement( "PGPKeyID" );
 
                     /* Write PGPKeyPacket element */
@@ -762,43 +762,50 @@ void XSecController::exportSignature(
             }
             else
             {
-                /* Write X509Data element */
-                xDocumentHandler->startElement(
-                    "X509Data",
-                    cssu::Reference< cssxs::XAttributeList > (new SvXMLAttributeList()));
+                assert(signatureInfo.GetSigningCertificate());
+                for (auto const& rData : signatureInfo.X509Datas)
                 {
-                    /* Write X509IssuerSerial element */
+                    /* Write X509Data element */
                     xDocumentHandler->startElement(
-                        "X509IssuerSerial",
-                        cssu::Reference< cssxs::XAttributeList > (new SvXMLAttributeList()));
-                    {
-                        /* Write X509IssuerName element */
-                        xDocumentHandler->startElement(
-                            "X509IssuerName",
-                            cssu::Reference< cssxs::XAttributeList > (new SvXMLAttributeList()));
-                        xDocumentHandler->characters( signatureInfo.ouX509IssuerName );
-                        xDocumentHandler->endElement( "X509IssuerName" );
-
-                        /* Write X509SerialNumber element */
-                        xDocumentHandler->startElement(
-                            "X509SerialNumber",
-                            cssu::Reference< cssxs::XAttributeList > (new SvXMLAttributeList()));
-                        xDocumentHandler->characters( signatureInfo.ouX509SerialNumber );
-                        xDocumentHandler->endElement( "X509SerialNumber" );
-                    }
-                    xDocumentHandler->endElement( "X509IssuerSerial" );
-
-                    /* Write X509Certificate element */
-                    if (!signatureInfo.ouX509Certificate.isEmpty())
+                        "X509Data",
+                        css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
                     {
-                        xDocumentHandler->startElement(
-                            "X509Certificate",
-                            cssu::Reference< cssxs::XAttributeList > (new SvXMLAttributeList()));
-                        xDocumentHandler->characters( signatureInfo.ouX509Certificate );
-                        xDocumentHandler->endElement( "X509Certificate" );
+                        for (auto const& it : rData)
+                        {
+                            /* Write X509IssuerSerial element */
+                            xDocumentHandler->startElement(
+                                "X509IssuerSerial",
+                                css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
+                            {
+                                /* Write X509IssuerName element */
+                                xDocumentHandler->startElement(
+                                    "X509IssuerName",
+                                    css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
+                                xDocumentHandler->characters(it.X509IssuerName);
+                                xDocumentHandler->endElement( "X509IssuerName" );
+
+                                /* Write X509SerialNumber element */
+                                xDocumentHandler->startElement(
+                                    "X509SerialNumber",
+                                    css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
+                                xDocumentHandler->characters(it.X509SerialNumber);
+                                xDocumentHandler->endElement( "X509SerialNumber" );
+                            }
+                            xDocumentHandler->endElement( "X509IssuerSerial" );
+
+                            /* Write X509Certificate element */
+                            if (!it.X509Certificate.isEmpty())
+                            {
+                                xDocumentHandler->startElement(
+                                    "X509Certificate",
+                                    css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
+                                xDocumentHandler->characters(it.X509Certificate);
+                                xDocumentHandler->endElement( "X509Certificate" );
+                            }
+                        }
                     }
+                    xDocumentHandler->endElement( "X509Data" );
                 }
-                xDocumentHandler->endElement( "X509Data" );
             }
         }
         xDocumentHandler->endElement( "KeyInfo" );
@@ -917,6 +924,15 @@ void XSecController::exportOOXMLSignature(const uno::Reference<embed::XStorage>&
     aExporter.writeSignature();
 }
 
+void XSecController::UpdateSignatureInformation(sal_Int32 const nSecurityId,
+    std::vector<SignatureInformation::X509Data> const& rDatas)
+{
+    SignatureInformation aInf( 0 );
+    int const nIndex = findSignatureInfor(nSecurityId);
+    assert(nIndex != -1); // nothing should touch this between parsing and verify
+    m_vInternalSignatureInformations[nIndex].signatureInfor.X509Datas = rDatas;
+}
+
 SignatureInformation XSecController::getSignatureInformation( sal_Int32 nSecurityId ) const
 {
     SignatureInformation aInf( 0 );
diff --git a/xmlsecurity/source/helper/xsecparser.cxx b/xmlsecurity/source/helper/xsecparser.cxx
index abc5fa0e0471..16dc6827f9b6 100644
--- a/xmlsecurity/source/helper/xsecparser.cxx
+++ b/xmlsecurity/source/helper/xsecparser.cxx
@@ -248,98 +248,79 @@ class XSecParser::DsX509CertificateContext
     : public XSecParser::Context
 {
     private:
-        OUString m_Value;
+        OUString & m_rValue;
 
     public:
         DsX509CertificateContext(XSecParser & rParser,
-                std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap)
+                std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
+                OUString & rValue)
             : XSecParser::Context(rParser, std::move(pOldNamespaceMap))
+            , m_rValue(rValue)
         {
         }
 
-        virtual void EndElement() override
-        {
-            m_rParser.m_pXSecController->setX509Certificate(m_Value);
-        }
-
         virtual void Characters(OUString const& rChars) override
         {
-            m_Value += rChars;
+            m_rValue += rChars;
         }
 };
 
 class XSecParser::DsX509SerialNumberContext
-    : public XSecParser::ReferencedContextImpl
+    : public XSecParser::Context
 {
     private:
-        OUString m_Value;
+        OUString & m_rValue;
 
     public:
         DsX509SerialNumberContext(XSecParser & rParser,
                 std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
-                bool const isReferenced)
-            : ReferencedContextImpl(rParser, std::move(pOldNamespaceMap), isReferenced)
+                OUString & rValue)
+            : XSecParser::Context(rParser, std::move(pOldNamespaceMap))
+            , m_rValue(rValue)
         {
         }
 
-        virtual void EndElement() override
-        {
-            if (m_isReferenced)
-            {
-                m_rParser.m_pXSecController->setX509SerialNumber(m_Value);
-            }
-            else
-            {
-                SAL_INFO("xmlsecurity.helper", "ignoring unsigned X509SerialNumber");
-            }
-        }
-
         virtual void Characters(OUString const& rChars) override
         {
-            m_Value += rChars;
+            m_rValue += rChars;
         }
 };
 
 class XSecParser::DsX509IssuerNameContext
-    : public XSecParser::ReferencedContextImpl
+    : public XSecParser::Context
 {
     private:
-        OUString m_Value;
+        OUString & m_rValue;
 
     public:
         DsX509IssuerNameContext(XSecParser & rParser,
                 std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
-                bool const isReferenced)
-            : ReferencedContextImpl(rParser, std::move(pOldNamespaceMap), isReferenced)
+                OUString & rValue)
+            : XSecParser::Context(rParser, std::move(pOldNamespaceMap))
+            , m_rValue(rValue)
         {
         }
 
-        virtual void EndElement() override
-        {
-            if (m_isReferenced)
-            {
-                m_rParser.m_pXSecController->setX509IssuerName(m_Value);
-            }
-            else
-            {
-                SAL_INFO("xmlsecurity.helper", "ignoring unsigned X509IssuerName");
-            }
-        }
-
         virtual void Characters(OUString const& rChars) override
         {
-            m_Value += rChars;
+            m_rValue += rChars;
         }
 };
 
 class XSecParser::DsX509IssuerSerialContext
-    : public XSecParser::ReferencedContextImpl
+    : public XSecParser::Context
 {
+    private:
+        OUString & m_rX509IssuerName;
+        OUString & m_rX509SerialNumber;
+
     public:
         DsX509IssuerSerialContext(XSecParser & rParser,
                 std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
-                bool const isReferenced)
-            : ReferencedContextImpl(rParser, std::move(pOldNamespaceMap), isReferenced)
+                OUString & rIssuerName, OUString & rSerialNumber)
+            : XSecParser::Context(rParser, std::move(pOldNamespaceMap))
+            , m_rX509IssuerName(rIssuerName)
+            , m_rX509SerialNumber(rSerialNumber)
         {
         }
 
@@ -349,20 +330,27 @@ class XSecParser::DsX509IssuerSerialContext
         {
             if (nNamespace == XML_NAMESPACE_DS && rName == "X509IssuerName")
             {
-                return o3tl::make_unique<DsX509IssuerNameContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return o3tl::make_unique<DsX509IssuerNameContext>(m_rParser, std::move(pOldNamespaceMap), m_rX509IssuerName);
             }
             if (nNamespace == XML_NAMESPACE_DS && rName == "X509SerialNumber")
             {
-                return o3tl::make_unique<DsX509SerialNumberContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return o3tl::make_unique<DsX509SerialNumberContext>(m_rParser, std::move(pOldNamespaceMap), m_rX509SerialNumber);
             }
             // missing: ds:X509SKI, ds:X509SubjectName, ds:X509CRL
             return XSecParser::Context::CreateChildContext(std::move(pOldNamespaceMap), nNamespace, rName);
         }
 };
 
+/// can't be sure what is supposed to happen here because the spec is clear as mud
 class XSecParser::DsX509DataContext
     : public XSecParser::Context
 {
+    private:
+        // sigh... "No ordering is implied by the above constraints."
+        // so store the ball of mud in vectors and try to figure it out later.
+        std::vector<std::pair<OUString, OUString>> m_X509IssuerSerials;
+        std::vector<OUString> m_X509Certificates;
+
     public:
         DsX509DataContext(XSecParser & rParser,
                 std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap)
@@ -370,18 +358,25 @@ class XSecParser::DsX509DataContext
         {
         }
 
+        virtual void EndElement() override
+        {
+            m_rParser.m_pXSecController->setX509Data(m_X509IssuerSerials, m_X509Certificates);
+        }
+
         virtual std::unique_ptr<Context> CreateChildContext(
             std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
             sal_uInt16 const nNamespace, OUString const& rName) override
         {
             if (nNamespace == XML_NAMESPACE_DS && rName == "X509IssuerSerial")
             {
-                // can't require KeyInfo to be signed so pass in *true*
-                return o3tl::make_unique<DsX509IssuerSerialContext>(m_rParser, std::move(pOldNamespaceMap), true);
+
+                m_X509IssuerSerials.emplace_back();
+                return o3tl::make_unique<DsX509IssuerSerialContext>(m_rParser, std::move(pOldNamespaceMap), m_X509IssuerSerials.back().first, m_X509IssuerSerials.back().second);
             }
             if (nNamespace == XML_NAMESPACE_DS && rName == "X509Certificate")
             {
-                return o3tl::make_unique<DsX509CertificateContext>(m_rParser, std::move(pOldNamespaceMap));
+                m_X509Certificates.emplace_back();
+                return o3tl::make_unique<DsX509CertificateContext>(m_rParser, std::move(pOldNamespaceMap), m_X509Certificates.back());
             }
             // missing: ds:X509SKI, ds:X509SubjectName, ds:X509CRL
             return XSecParser::Context::CreateChildContext(std::move(pOldNamespaceMap), nNamespace, rName);
@@ -940,30 +935,20 @@ class XSecParser::LoSignatureLineContext
 };
 
 class XSecParser::XadesCertDigestContext
-    : public XSecParser::ReferencedContextImpl
+    : public XSecParser::Context
 {
     private:
-        OUString m_Value;
-        sal_Int32 m_nReferenceDigestID = css::xml::crypto::DigestID::SHA1;
+        OUString & m_rDigestValue;
+        sal_Int32 & m_rReferenceDigestID;
 
     public:
         XadesCertDigestContext(XSecParser & rParser,
                 std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
-                bool const isReferenced)
-            : ReferencedContextImpl(rParser, std::move(pOldNamespaceMap), isReferenced)
-        {
-        }
-
-        virtual void EndElement() override
+                OUString & rDigestValue, sal_Int32 & rReferenceDigestID)
+            : XSecParser::Context(rParser, std::move(pOldNamespaceMap))
+            , m_rDigestValue(rDigestValue)
+            , m_rReferenceDigestID(rReferenceDigestID)
         {
-            if (m_isReferenced)
-            {
-                m_rParser.m_pXSecController->setCertDigest(m_Value/* FIXME , m_nReferenceDigestID*/);
-            }
-            else
-            {
-                SAL_INFO("xmlsecurity.helper", "ignoring unsigned CertDigest");
-            }
         }
 
         virtual std::unique_ptr<Context> CreateChildContext(
@@ -972,11 +957,11 @@ class XSecParser::XadesCertDigestContext
         {
             if (nNamespace == XML_NAMESPACE_DS && rName == "DigestMethod")
             {
-                return o3tl::make_unique<DsDigestMethodContext>(m_rParser, std::move(pOldNamespaceMap), m_nReferenceDigestID);
+                return o3tl::make_unique<DsDigestMethodContext>(m_rParser, std::move(pOldNamespaceMap), m_rReferenceDigestID);
             }
             if (nNamespace == XML_NAMESPACE_DS && rName == "DigestValue")
             {
-                return o3tl::make_unique<DsDigestValueContext>(m_rParser, std::move(pOldNamespaceMap), m_Value);
+                return o3tl::make_unique<DsDigestValueContext>(m_rParser, std::move(pOldNamespaceMap), m_rDigestValue);
             }
             return XSecParser::Context::CreateChildContext(std::move(pOldNamespaceMap), nNamespace, rName);
         }
@@ -985,6 +970,12 @@ class XSecParser::XadesCertDigestContext
 class XSecParser::XadesCertContext
     : public XSecParser::ReferencedContextImpl
 {
+    private:
+        sal_Int32 m_nReferenceDigestID = css::xml::crypto::DigestID::SHA1;
+        OUString m_CertDigest;
+        OUString m_X509IssuerName;
+        OUString m_X509SerialNumber;
+
     public:
         XadesCertContext(XSecParser & rParser,
                 std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
@@ -993,17 +984,29 @@ class XSecParser::XadesCertContext
         {
         }
 
+        virtual void EndElement() override
+        {
+            if (m_isReferenced)
+            {
+                m_rParser.m_pXSecController->setX509CertDigest(m_CertDigest, m_nReferenceDigestID, m_X509IssuerName, m_X509SerialNumber);
+            }
+            else
+            {
+                SAL_INFO("xmlsecurity.helper", "ignoring unsigned xades:Cert");
+            }
+        }
+
         virtual std::unique_ptr<Context> CreateChildContext(
             std::unique_ptr<SvXMLNamespaceMap> pOldNamespaceMap,
             sal_uInt16 const nNamespace, OUString const& rName) override
         {
             if (nNamespace == XML_NAMESPACE_XADES132 && rName == "CertDigest")
             {
-                return o3tl::make_unique<XadesCertDigestContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return o3tl::make_unique<XadesCertDigestContext>(m_rParser, std::move(pOldNamespaceMap), m_CertDigest, m_nReferenceDigestID);
             }
             if (nNamespace == XML_NAMESPACE_XADES132 && rName == "IssuerSerial")
             {
-                return o3tl::make_unique<DsX509IssuerSerialContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return o3tl::make_unique<DsX509IssuerSerialContext>(m_rParser, std::move(pOldNamespaceMap), m_X509IssuerName, m_X509SerialNumber);
             }
             return XSecParser::Context::CreateChildContext(std::move(pOldNamespaceMap), nNamespace, rName);
         }
diff --git a/xmlsecurity/source/helper/xsecsign.cxx b/xmlsecurity/source/helper/xsecsign.cxx
index 03b553846d46..e2be55a0623e 100644
--- a/xmlsecurity/source/helper/xsecsign.cxx
+++ b/xmlsecurity/source/helper/xsecsign.cxx
@@ -210,6 +210,7 @@ void XSecController::signAStream( sal_Int32 securityId, const OUString& uri, boo
     }
 }
 
+// note: this is called when creating a new signature from scratch
 void XSecController::setX509Certificate(
     sal_Int32 nSecurityId,
     const OUString& ouX509IssuerName,
@@ -222,26 +223,32 @@ void XSecController::setX509Certificate(
     if ( index == -1 )
     {
         InternalSignatureInformation isi(nSecurityId, nullptr);
-        isi.signatureInfor.ouX509IssuerName = ouX509IssuerName;
-        isi.signatureInfor.ouX509SerialNumber = ouX509SerialNumber;
-        isi.signatureInfor.ouX509Certificate = ouX509Cert;
-        isi.signatureInfor.ouCertDigest = ouX509CertDigest;
+        isi.signatureInfor.X509Datas.clear();
+        isi.signatureInfor.X509Datas.emplace_back();
+        isi.signatureInfor.X509Datas.back().emplace_back();
+        isi.signatureInfor.X509Datas.back().back().X509IssuerName = ouX509IssuerName;
+        isi.signatureInfor.X509Datas.back().back().X509SerialNumber = ouX509SerialNumber;
+        isi.signatureInfor.X509Datas.back().back().X509Certificate = ouX509Cert;
+        isi.signatureInfor.X509Datas.back().back().CertDigest = ouX509CertDigest;
         m_vInternalSignatureInformations.push_back( isi );
     }
     else
     {
         SignatureInformation &si
             = m_vInternalSignatureInformations[index].signatureInfor;
-        si.ouX509IssuerName = ouX509IssuerName;
-        si.ouX509SerialNumber = ouX509SerialNumber;
-        si.ouX509Certificate = ouX509Cert;
-        si.ouCertDigest = ouX509CertDigest;
+        si.X509Datas.clear();
+        si.X509Datas.emplace_back();
+        si.X509Datas.back().emplace_back();
+        si.X509Datas.back().back().X509IssuerName = ouX509IssuerName;
+        si.X509Datas.back().back().X509SerialNumber = ouX509SerialNumber;
+        si.X509Datas.back().back().X509Certificate = ouX509Cert;
+        si.X509Datas.back().back().CertDigest = ouX509CertDigest;
     }
 }
 
 void XSecController::setGpgCertificate(
         sal_Int32 nSecurityId,
-        const OUString& ouCertDigest,
+        const OUString& ouKeyDigest,
         const OUString& ouCert,
         const OUString& ouOwner)
 {
@@ -252,16 +259,17 @@ void XSecController::setGpgCertificate(
         InternalSignatureInformation isi(nSecurityId, nullptr);
         isi.signatureInfor.ouGpgCertificate = ouCert;
         isi.signatureInfor.ouGpgOwner = ouOwner;
-        isi.signatureInfor.ouCertDigest = ouCertDigest;
+        isi.signatureInfor.ouGpgKeyID = ouKeyDigest;
         m_vInternalSignatureInformations.push_back( isi );
     }
     else
     {
         SignatureInformation &si
             = m_vInternalSignatureInformations[index].signatureInfor;
+        si.X509Datas.clear(); // it is a PGP signature now
         si.ouGpgCertificate = ouCert;
         si.ouGpgOwner = ouOwner;
-        si.ouCertDigest = ouCertDigest;
+        si.ouGpgKeyID = ouKeyDigest;
     }
 }
 
diff --git a/xmlsecurity/source/helper/xsecverify.cxx b/xmlsecurity/source/helper/xsecverify.cxx
index 5c1ee3b42e1b..7da0e0ba1484 100644
--- a/xmlsecurity/source/helper/xsecverify.cxx
+++ b/xmlsecurity/source/helper/xsecverify.cxx
@@ -21,6 +21,7 @@
 #include "xsecctl.hxx"
 #include "xsecparser.hxx"
 #include "ooxmlsecparser.hxx"
+#include <biginteger.hxx>
 #include "framework/signatureverifierimpl.hxx"
 #include "framework/saxeventkeeperimpl.hxx"
 #include "gpg/xmlsignature_gpgimpl.hxx"
@@ -226,7 +227,9 @@ void XSecController::setReferenceCount() const
     }
 }
 
-void XSecController::setX509IssuerName( OUString& ouX509IssuerName )
+void XSecController::setX509Data(
+        std::vector<std::pair<OUString, OUString>> & rX509IssuerSerials,
+        std::vector<OUString> const& rX509Certificates)
 {
     if (m_vInternalSignatureInformations.empty())
     {
@@ -234,32 +237,56 @@ void XSecController::setX509IssuerName( OUString& ouX509IssuerName )
         return;
     }
     InternalSignatureInformation &isi = m_vInternalSignatureInformations.back();
-    isi.signatureInfor.ouX509IssuerName = ouX509IssuerName;
-}
 
-void XSecController::setX509SerialNumber( OUString& ouX509SerialNumber )
-{
-    if (m_vInternalSignatureInformations.empty())
+    SignatureInformation::X509Data data;
+    // due to the excessive flexibility of the spec it's possible that there
+    // is both a reference to a cert and the cert itself in one X509Data
+    for (OUString const& it : rX509Certificates)
     {
-        SAL_INFO("xmlsecurity.helper","XSecController::setX509SerialNumber: no signature");
-        return;
+        try
+        {
+            data.emplace_back();
+            data.back().X509Certificate = it;
+            uno::Reference<xml::crypto::XSecurityEnvironment> const xSecEnv(m_xSecurityContext->getSecurityEnvironment());
+            uno::Reference<security::XCertificate> const xCert(xSecEnv->createCertificateFromAscii(it));
+            if (!xCert.is())
+            {
+                SAL_INFO("xmlsecurity.helper", "cannot parse X509Certificate");
+                continue; // will be handled in CheckX509Data
+            }
+            OUString const issuerName(xCert->getIssuerName());
+            OUString const serialNumber(xmlsecurity::bigIntegerToNumericString(xCert->getSerialNumber()));
+            auto const iter = std::find_if(rX509IssuerSerials.begin(), rX509IssuerSerials.end(),
+                [&](std::pair<OUString, OUString> const& rX509IssuerSerial) {
+                    return xmlsecurity::EqualDistinguishedNames(issuerName, rX509IssuerSerial.first)
+                        && serialNumber == rX509IssuerSerial.second;
+                });
+            if (iter != rX509IssuerSerials.end())
+            {
+                data.back().X509IssuerName = iter->first;
+                data.back().X509SerialNumber = iter->second;
+                rX509IssuerSerials.erase(iter);
+            }
+        }
+        catch (uno::Exception const&)
+        {
+            SAL_INFO("xmlsecurity.helper", "cannot parse X509Certificate");
+        }
     }
-    InternalSignatureInformation &isi = m_vInternalSignatureInformations.back();
-    isi.signatureInfor.ouX509SerialNumber = ouX509SerialNumber;
-}
-
-void XSecController::setX509Certificate( OUString& ouX509Certificate )
-{
-    if (m_vInternalSignatureInformations.empty())
+    // now handle any that are left...
+    for (auto const& it : rX509IssuerSerials)
     {
-        SAL_INFO("xmlsecurity.helper","XSecController::setX509Certificate: no signature");
-        return;
+        data.emplace_back();
+        data.back().X509IssuerName = it.first;
+        data.back().X509SerialNumber = it.second;
+    }
+    if (!data.empty())
+    {
+        isi.signatureInfor.X509Datas.push_back(data);
     }
-    InternalSignatureInformation &isi = m_vInternalSignatureInformations.back();
-    isi.signatureInfor.ouX509Certificate = ouX509Certificate;
 }
 
-void XSecController::setSignatureValue( OUString& ouSignatureValue )
+void XSecController::setSignatureValue( OUString const & ouSignatureValue )
 {
     if (m_vInternalSignatureInformations.empty())
     {
@@ -270,7 +297,7 @@ void XSecController::setSignatureValue( OUString& ouSignatureValue )
     isi.signatureInfor.ouSignatureValue = ouSignatureValue;
 }
 
-void XSecController::setDigestValue( sal_Int32 nDigestID, OUString& ouDigestValue )
+void XSecController::setDigestValue( sal_Int32 nDigestID, OUString const & ouDigestValue )
 {
     if (m_vInternalSignatureInformations.empty())
     {
@@ -289,7 +316,7 @@ void XSecController::setDigestValue( sal_Int32 nDigestID, OUString& ouDigestValu
     reference.ouDigestValue = ouDigestValue;
 }
 
-void XSecController::setGpgKeyID( OUString& ouKeyID )
+void XSecController::setGpgKeyID( OUString const & ouKeyID )
 {
     if (m_vInternalSignatureInformations.empty())
     {
@@ -300,7 +327,7 @@ void XSecController::setGpgKeyID( OUString& ouKeyID )
     isi.signatureInfor.ouGpgKeyID = ouKeyID;
 }
 
-void XSecController::setGpgCertificate( OUString& ouGpgCert )
+void XSecController::setGpgCertificate( OUString const & ouGpgCert )
 {
     if (m_vInternalSignatureInformations.empty())
     {
@@ -311,7 +338,7 @@ void XSecController::setGpgCertificate( OUString& ouGpgCert )
     isi.signatureInfor.ouGpgCertificate = ouGpgCert;
 }
 
-void XSecController::setGpgOwner( OUString& ouGpgOwner )
+void XSecController::setGpgOwner( OUString const & ouGpgOwner )
 {
     if (m_vInternalSignatureInformations.empty())
     {
@@ -366,13 +393,67 @@ void XSecController::setSignatureBytes(const uno::Sequence<sal_Int8>& rBytes)
     rInformation.signatureInfor.aSignatureBytes = rBytes;
 }
 
-void XSecController::setCertDigest(const OUString& rCertDigest)
+void XSecController::setX509CertDigest(
+    OUString const& rCertDigest, sal_Int32 const /*TODO nReferenceDigestID*/,
+    OUString const& rX509IssuerName, OUString const& rX509SerialNumber)
 {
     if (m_vInternalSignatureInformations.empty())
         return;
 
     InternalSignatureInformation& rInformation = m_vInternalSignatureInformations.back();
-    rInformation.signatureInfor.ouCertDigest = rCertDigest;
+    for (auto & rData : rInformation.signatureInfor.X509Datas)
+    {
+        for (auto & it : rData)
+        {
+            if (xmlsecurity::EqualDistinguishedNames(it.X509IssuerName, rX509IssuerName)
+                && it.X509SerialNumber == rX509SerialNumber)
+            {
+                it.CertDigest = rCertDigest;
+                return;
+            }
+        }
+    }
+    // fall-back: read the actual certificates
+    for (auto & rData : rInformation.signatureInfor.X509Datas)
+    {
+        for (auto & it : rData)
+        {
+            if (!it.X509Certificate.isEmpty())
+            {
+                try
+                {
+                    uno::Reference<xml::crypto::XSecurityEnvironment> const xSecEnv(m_xSecurityContext->getSecurityEnvironment());
+                    uno::Reference<security::XCertificate> const xCert(xSecEnv->createCertificateFromAscii(it.X509Certificate));
+                    if (!xCert.is())
+                    {
+                        SAL_INFO("xmlsecurity.helper", "cannot parse X509Certificate");
+                    }
+                    else if (xmlsecurity::EqualDistinguishedNames(xCert->getIssuerName(),rX509IssuerName)
+                        && xmlsecurity::bigIntegerToNumericString(xCert->getSerialNumber()) == rX509SerialNumber)
+                    {
+                        it.CertDigest = rCertDigest;
+                        // note: testInsertCertificate_PEM_DOCX requires these!
+                        it.X509SerialNumber = rX509SerialNumber;
+                        it.X509IssuerName = rX509IssuerName;
+                        return;
+                    }
+                }
+                catch (uno::Exception const&)
+                {
+                    SAL_INFO("xmlsecurity.helper", "cannot parse X509Certificate");
+                }
+            }
+        }
+    }
+    if (!rInformation.signatureInfor.ouGpgCertificate.isEmpty())
+    {
+        SAL_INFO_IF(rCertDigest != rInformation.signatureInfor.ouGpgKeyID,
+            "xmlsecurity.helper", "PGPKeyID vs CertDigest mismatch");
+    }
+    else
+    {
+        SAL_INFO("xmlsecurity.helper", "cannot find X509Data for CertDigest");
+    }
 }
 
 void XSecController::addEncapsulatedX509Certificate(const OUString& rEncapsulatedX509Certificate)
diff --git a/xmlsecurity/source/pdfio/pdfdocument.cxx b/xmlsecurity/source/pdfio/pdfdocument.cxx
index 5420196df7d8..effc754f8ec7 100644
--- a/xmlsecurity/source/pdfio/pdfdocument.cxx
+++ b/xmlsecurity/source/pdfio/pdfdocument.cxx
@@ -553,7 +553,12 @@ bool ValidateSignature(SvStream& rStream, vcl::filter::PDFObjectElement* pSignat
             aDerCert[i] = pCertificate->derCert.data[i];
         OUStringBuffer aBuffer;
         sax::Converter::encodeBase64(aBuffer, aDerCert);
-        rInformation.ouX509Certificate = aBuffer.makeStringAndClear();
+        SignatureInformation::X509Data temp;
+        temp.emplace_back();
+        temp.back().X509Certificate = aBuffer.makeStringAndClear();
+        temp.back().X509Subject = OUString(pCertificate->subjectName, PL_strlen(pCertificate->subjectName), RTL_TEXTENCODING_UTF8);
+        rInformation.X509Datas.clear();
+        rInformation.X509Datas.emplace_back(temp);
     }
 
     PRTime nSigningTime;
@@ -755,7 +760,12 @@ bool ValidateSignature(SvStream& rStream, vcl::filter::PDFObjectElement* pSignat
             aDerCert[i] = pSignerCertContext->pbCertEncoded[i];
         OUStringBuffer aBuffer;
         sax::Converter::encodeBase64(aBuffer, aDerCert);
-        rInformation.ouX509Certificate = aBuffer.makeStringAndClear();
+        SignatureInformation::X509Data temp;
+        temp.emplace_back();
+        temp.back().X509Certificate = aBuffer.makeStringAndClear();
+        temp.back().X509Subject = GetSubjectName(pSignerCertContext);
+        rInformation.X509Datas.clear();
+        rInformation.X509Datas.emplace_back(temp);
     }
 
     if (bNonDetached)
diff --git a/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx b/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
index 35b3835a2afe..5852c7c32bb3 100644
--- a/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
+++ b/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
@@ -24,6 +24,7 @@
 #include <comphelper/windowserrorstring.hxx>
 #include "x509certificate_mscryptimpl.hxx"
 #include "certificateextension_xmlsecimpl.hxx"
+#include <biginteger.hxx>
 #include "sanextension_mscryptimpl.hxx"
 
 #include "oid.hxx"
@@ -658,4 +659,50 @@ sal_Int32 SAL_CALL X509Certificate_MSCryptImpl::getCertificateUsage(  )
     return usage;
 }
 
+namespace xmlsecurity {
+
+static bool EncodeDistinguishedName(OUString const& rName, CERT_NAME_BLOB & rBlob)
+{
+    LPCWSTR pszError;
+    if (!CertStrToNameW(X509_ASN_ENCODING,
+            reinterpret_cast<LPCWSTR>(rName.getStr()), CERT_X500_NAME_STR,
+            nullptr, nullptr, &rBlob.cbData, &pszError))
+    {
+        SAL_INFO("xmlsecurity.xmlsec", "CertStrToNameW failed: " << WindowsErrorString(GetLastError()) << "; " << reinterpret_cast<char16_t const*>(pszError));
+        return false;
+    }
+    rBlob.pbData = new BYTE[rBlob.cbData];
+    if (!CertStrToNameW(X509_ASN_ENCODING,
+            reinterpret_cast<LPCWSTR>(rName.getStr()), CERT_X500_NAME_STR,
+            nullptr, rBlob.pbData, &rBlob.cbData, &pszError))
+    {
+        SAL_INFO("xmlsecurity.xmlsec", "CertStrToNameW failed: " << WindowsErrorString(GetLastError()) << "; " << reinterpret_cast<char16_t const*>(pszError));
+        return false;
+    }
+    return true;
+}
+
+bool EqualDistinguishedNames(
+        OUString const& rName1, OUString const& rName2)
+{
+    CERT_NAME_BLOB blob1;
+    if (!EncodeDistinguishedName(rName1, blob1))
+    {
+        return false;
+    }
+    CERT_NAME_BLOB blob2;
+    if (!EncodeDistinguishedName(rName2, blob2))
+    {
+        delete[] blob1.pbData;
+        return false;
+    }
+    bool const ret(CertCompareCertificateName(X509_ASN_ENCODING,
+            &blob1, &blob2) == TRUE);
+    delete[] blob2.pbData;
+    delete[] blob1.pbData;
+    return ret;
+}
+
+} // namespace xmlsecurity
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/xmlsecurity/source/xmlsec/mscrypt/xmlsignature_mscryptimpl.cxx b/xmlsecurity/source/xmlsec/mscrypt/xmlsignature_mscryptimpl.cxx
index 08b4bf2ddc51..9751a21fe937 100644
--- a/xmlsecurity/source/xmlsec/mscrypt/xmlsignature_mscryptimpl.cxx
+++ b/xmlsecurity/source/xmlsec/mscrypt/xmlsignature_mscryptimpl.cxx
@@ -18,6 +18,7 @@
  */
 
 #include <sal/config.h>
+#include <sal/log.hxx>
 #include <rtl/uuid.h>
 
 #include <com/sun/star/xml/crypto/SecurityOperationStatus.hpp>
@@ -224,6 +225,7 @@ SAL_CALL XMLSignature_MSCryptImpl::validate(
                  ++nReferenceGood;
         }
     }
+    SAL_INFO("xmlsecurity.xmlsec", "xmlSecDSigCtxVerify status " << pDsigCtx->status << ", references good " << nReferenceGood << " of " << nReferenceCount);
 
     if (rs == 0 && nReferenceCount == nReferenceGood)
     {
diff --git a/xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx b/xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx
index 079be582e02b..245dfe29887a 100644
--- a/xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx
+++ b/xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx
@@ -31,6 +31,7 @@
 #include <rtl/ref.hxx>
 #include "x509certificate_nssimpl.hxx"
 
+#include <biginteger.hxx>
 #include "certificateextension_xmlsecimpl.hxx"
 
 #include "sanextension_nssimpl.hxx"
@@ -492,4 +493,28 @@ sal_Int32 SAL_CALL X509Certificate_NssImpl::getCertificateUsage(  )
     return usage;
 }
 
+namespace xmlsecurity {
+
+bool EqualDistinguishedNames(
+        OUString const& rName1, OUString const& rName2)
+{
+    CERTName *const pName1(CERT_AsciiToName(OUStringToOString(rName1, RTL_TEXTENCODING_UTF8).getStr()));
+    if (pName1 == nullptr)
+    {
+        return false;
+    }
+    CERTName *const pName2(CERT_AsciiToName(OUStringToOString(rName2, RTL_TEXTENCODING_UTF8).getStr()));
+    if (pName2 == nullptr)
+    {
+        CERT_DestroyName(pName1);
+        return false;
+    }
+    bool const ret(CERT_CompareName(pName1, pName2) == SECEqual);
+    CERT_DestroyName(pName2);
+    CERT_DestroyName(pName1);
+    return ret;
+}
+
+} // namespace xmlsecurity
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/xmlsecurity/source/xmlsec/nss/xmlsignature_nssimpl.cxx b/xmlsecurity/source/xmlsec/nss/xmlsignature_nssimpl.cxx
index a78ff38695ef..a5ee64b16e88 100644
--- a/xmlsecurity/source/xmlsec/nss/xmlsignature_nssimpl.cxx
+++ b/xmlsecurity/source/xmlsec/nss/xmlsignature_nssimpl.cxx
@@ -32,6 +32,10 @@
 
 #include "xmlsec-wrapper.h"
 
+#include <sal/log.hxx>
+
+#include <com/sun/star/xml/crypto/XXMLSignature.hpp>
+
 using namespace ::com::sun::star::uno ;
 using namespace ::com::sun::star::lang ;
 using ::com::sun::star::lang::XMultiServiceFactory ;
@@ -239,6 +243,7 @@ SAL_CALL XMLSignature_NssImpl::validate(
                     ++nReferenceGood;
             }
         }
+        SAL_INFO("xmlsecurity.xmlsec", "xmlSecDSigCtxVerify status " << pDsigCtx->status << ", references good " << nReferenceGood << " of " << nReferenceCount);
 
         if (rs == 0 && pDsigCtx->status == xmlSecDSigStatusSucceeded && nReferenceCount == nReferenceGood)
         {