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>

Change-Id: I9633a980b0c18d58dfce24fc59396a833498a77d

22 files changed, 679 insertions, 210 deletions

diff --git a/include/svl/sigstruct.hxx b/include/svl/sigstruct.hxx
index 891f620ec547..02b5c11e73a3 100644
--- a/include/svl/sigstruct.hxx
+++ b/include/svl/sigstruct.hxx
@@ -88,9 +88,30 @@ 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;
@@ -123,8 +144,6 @@ struct SignatureInformation
     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;
     /// Valid and invalid signature line images
     css::uno::Reference<css::graphic::XGraphic> aValidSignatureImage;
     css::uno::Reference<css::graphic::XGraphic> aInvalidSignatureImage;
@@ -139,9 +158,6 @@ struct SignatureInformation
     /// For PDF: the byte range doesn't cover the whole document.
     bool bPartialDocumentSignature;
 
-    /// The certificate owner (aka subject).
-    OUString ouSubject;
-
     svl::crypto::SignatureMethodAlgorithm eAlgorithmID;
 
     SignatureInformation( sal_Int32 nId )
diff --git a/svl/source/crypto/cryptosign.cxx b/svl/source/crypto/cryptosign.cxx
index 96c349d68861..ee86756a02a2 100644
--- a/svl/source/crypto/cryptosign.cxx
+++ b/svl/source/crypto/cryptosign.cxx
@@ -2077,8 +2077,12 @@ bool Signing::Verify(const std::vector<unsigned char>& aData,
             aDerCert[i] = pCertificate->derCert.data[i];
         OUStringBuffer aBuffer;
         comphelper::Base64::encode(aBuffer, aDerCert);
-        rInformation.ouX509Certificate = aBuffer.makeStringAndClear();
-        rInformation.ouSubject = OUString(pCertificate->subjectName, PL_strlen(pCertificate->subjectName), RTL_TEXTENCODING_UTF8);
+        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;
@@ -2257,8 +2261,12 @@ bool Signing::Verify(const std::vector<unsigned char>& aData,
             aDerCert[i] = pSignerCertContext->pbCertEncoded[i];
         OUStringBuffer aBuffer;
         comphelper::Base64::encode(aBuffer, aDerCert);
-        rInformation.ouX509Certificate = aBuffer.makeStringAndClear();
-        rInformation.ouSubject = GetSubjectName(pSignerCertContext);
+        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/sw/source/core/edit/edfcol.cxx b/sw/source/core/edit/edfcol.cxx
index ee76998aac75..2bc3835783a0 100644
--- a/sw/source/core/edit/edfcol.cxx
+++ b/sw/source/core/edit/edfcol.cxx
@@ -398,7 +398,8 @@ lcl_MakeParagraphSignatureFieldText(const SignatureDescr& aDescr,
             valid = svl::crypto::Signing::Verify(data, false, sig, aInfo);
             valid = valid && aInfo.nStatus == css::xml::crypto::SecurityOperationStatus_OPERATION_SUCCEEDED;
 
-            msg = SwResId(STR_SIGNED_BY) + ": " + aInfo.ouSubject + ", ";
+            assert(aInfo.GetSigningCertificate()); // it was valid
+            msg = SwResId(STR_SIGNED_BY) + ": " + aInfo.GetSigningCertificate()->X509Subject + ", ";
             msg += aDescr.msDate;
             msg += (!aDescr.msUsage.isEmpty() ? (" (" + aDescr.msUsage + "): ") : OUString(": "));
             msg += (valid ? SwResId(STR_VALID) : SwResId(STR_INVALID));
diff --git a/xmlsecurity/inc/biginteger.hxx b/xmlsecurity/inc/biginteger.hxx
index d07ecf45d8af..8b4d8a9143b5 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/xmlsignaturehelper.hxx b/xmlsecurity/inc/xmlsignaturehelper.hxx
index 02128bb4f6a8..9d6bf7b3c6de 100644
--- a/xmlsecurity/inc/xmlsignaturehelper.hxx
+++ b/xmlsecurity/inc/xmlsignaturehelper.hxx
@@ -37,6 +37,9 @@
 #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;
 
 namespace com {
@@ -95,6 +98,15 @@ 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 a8167949e159..1b61be773f7d 100644
--- a/xmlsecurity/inc/xsecctl.hxx
+++ b/xmlsecurity/inc/xsecctl.hxx
@@ -270,9 +270,13 @@ private:
         sal_Int32 nDigestID );
     void setReferenceCount() const;
 
-    void setX509IssuerName( OUString const & ouX509IssuerName );
-    void setX509SerialNumber( OUString const & ouX509SerialNumber );
-    void setX509Certificate( OUString const & ouX509Certificate );
+    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 );
@@ -281,7 +285,6 @@ private:
 
     void setDate(OUString const& rId, OUString const& ouDate);
     void setDescription(OUString const& rId, OUString const& rDescription);
-    void setCertDigest(const OUString& rCertDigest);
     void setValidSignatureImage(const OUString& rValidSigImg);
     void setInvalidSignatureImage(const OUString& rInvalidSigImg);
     void setSignatureLineId(const OUString& rSignatureLineId);
@@ -310,6 +313,9 @@ 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,
diff --git a/xmlsecurity/source/component/documentdigitalsignatures.cxx b/xmlsecurity/source/component/documentdigitalsignatures.cxx
index 392dba4babd9..bedc07e261df 100644
--- a/xmlsecurity/source/component/documentdigitalsignatures.cxx
+++ b/xmlsecurity/source/component/documentdigitalsignatures.cxx
@@ -486,27 +486,36 @@ 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 ) );
-
+                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,
-                                                                            Sequence<Reference<css::security::XCertificate> >());
-                } catch (SecurityException& ) {
-                    OSL_FAIL("Verification of certificate failed");
-                    rSigInfo.CertificateStatus = css::security::CertificateValidity::INVALID;
+                    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 if (xGpgSecEnv.is()) // 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
@@ -591,11 +600,15 @@ 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();
@@ -603,7 +616,8 @@ 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 104206ab5c4f..dd5ce3b78d37 100644
--- a/xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx
+++ b/xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx
@@ -609,7 +609,7 @@ 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";
@@ -721,8 +721,8 @@ 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 (xSecEnv.is() && !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
@@ -734,9 +734,12 @@ 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() && xSecEnv.is())
-        xCert = xSecEnv->getCertificate( rInfo.ouX509IssuerName, xmlsecurity::numericStringToBigInteger( rInfo.ouX509SerialNumber ) );
-    if (!xCert.is() && xGpgSecEnv.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 37342b536349..397543cd2457 100644
--- a/xmlsecurity/source/helper/documentsignaturehelper.cxx
+++ b/xmlsecurity/source/helper/documentsignaturehelper.cxx
@@ -545,6 +545,29 @@ 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,
@@ -561,26 +584,26 @@ 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 c88c18964b22..3f48f20bafff 100644
--- a/xmlsecurity/source/helper/documentsignaturemanager.cxx
+++ b/xmlsecurity/source/helper/documentsignaturemanager.cxx
@@ -555,6 +555,18 @@ void DocumentSignatureManager::read(bool bUseTempStream, bool bCacheLastSignatur
                                                             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 fbb926b63a6e..942a3c0a4618 100644
--- a/xmlsecurity/source/helper/ooxmlsecexporter.cxx
+++ b/xmlsecurity/source/helper/ooxmlsecexporter.cxx
@@ -186,13 +186,21 @@ 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 5a426e7da03d..e329b8d35176 100644
--- a/xmlsecurity/source/helper/ooxmlsecparser.cxx
+++ b/xmlsecurity/source/helper/ooxmlsecparser.cxx
@@ -176,9 +176,22 @@ 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")
@@ -193,17 +206,18 @@ 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;
     }
     else if (rName == "Object")
diff --git a/xmlsecurity/source/helper/pdfsignaturehelper.cxx b/xmlsecurity/source/helper/pdfsignaturehelper.cxx
index 49c43fa1f679..0311ffe48b23 100644
--- a/xmlsecurity/source/helper/pdfsignaturehelper.cxx
+++ b/xmlsecurity/source/helper/pdfsignaturehelper.cxx
@@ -84,8 +84,12 @@ PDFSignatureHelper::GetDocumentSignatureInformations(
         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 09487ac673e9..86982f03dacf 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>
 
@@ -48,6 +49,8 @@
 #include <comphelper/sequence.hxx>
 #include <tools/diagnose_ex.h>
 
+#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"
@@ -575,4 +578,162 @@ void XMLSignatureHelper::CreateAndWriteOOXMLSignature(const uno::Reference<embed
     xSaxWriter->endDocument();
 }
 
+/** 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 ed7c43c7dfdf..b14fed88adc0 100644
--- a/xmlsecurity/source/helper/xsecctl.cxx
+++ b/xmlsecurity/source/helper/xsecctl.cxx
@@ -739,7 +739,7 @@ void XSecController::exportSignature(
                     xDocumentHandler->startElement(
                         "PGPKeyID",
                         css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
-                    xDocumentHandler->characters( signatureInfo.ouCertDigest );
+                    xDocumentHandler->characters(signatureInfo.ouGpgKeyID);
                     xDocumentHandler->endElement( "PGPKeyID" );
 
                     /* Write PGPKeyPacket element */
@@ -763,43 +763,50 @@ void XSecController::exportSignature(
             }
             else
             {
-                /* Write X509Data element */
-                xDocumentHandler->startElement(
-                    "X509Data",
-                    css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
+                assert(signatureInfo.GetSigningCertificate());
+                for (auto const& rData : signatureInfo.X509Datas)
                 {
-                    /* Write X509IssuerSerial element */
+                    /* Write X509Data element */
                     xDocumentHandler->startElement(
-                        "X509IssuerSerial",
+                        "X509Data",
                         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( signatureInfo.ouX509IssuerName );
-                        xDocumentHandler->endElement( "X509IssuerName" );
-
-                        /* Write X509SerialNumber element */
-                        xDocumentHandler->startElement(
-                            "X509SerialNumber",
-                            css::uno::Reference< css::xml::sax::XAttributeList > (new SvXMLAttributeList()));
-                        xDocumentHandler->characters( signatureInfo.ouX509SerialNumber );
-                        xDocumentHandler->endElement( "X509SerialNumber" );
-                    }
-                    xDocumentHandler->endElement( "X509IssuerSerial" );
-
-                    /* Write X509Certificate element */
-                    if (!signatureInfo.ouX509Certificate.isEmpty())
-                    {
-                        xDocumentHandler->startElement(
-                            "X509Certificate",
-                            css::uno::Reference< css::xml::sax::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" );
@@ -918,6 +925,15 @@ 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 7122f9f71905..ff70d888eb51 100644
--- a/xmlsecurity/source/helper/xsecparser.cxx
+++ b/xmlsecurity/source/helper/xsecparser.cxx
@@ -243,98 +243,79 @@ 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)
-        {
-        }
-
-        virtual void EndElement() override
+                OUString & rValue)
+            : XSecParser::Context(rParser, std::move(pOldNamespaceMap))
+            , m_rValue(rValue)
         {
-            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)
-        {
-        }
-
-        virtual void EndElement() override
+                OUString & rValue)
+            : XSecParser::Context(rParser, std::move(pOldNamespaceMap))
+            , m_rValue(rValue)
         {
-            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)
         {
         }
 
@@ -344,20 +325,27 @@ class XSecParser::DsX509IssuerSerialContext
         {
             if (nNamespace == XML_NAMESPACE_DS && rName == "X509IssuerName")
             {
-                return std::make_unique<DsX509IssuerNameContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return std::make_unique<DsX509IssuerNameContext>(m_rParser, std::move(pOldNamespaceMap), m_rX509IssuerName);
             }
             if (nNamespace == XML_NAMESPACE_DS && rName == "X509SerialNumber")
             {
-                return std::make_unique<DsX509SerialNumberContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return std::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)
@@ -365,18 +353,24 @@ 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 std::make_unique<DsX509IssuerSerialContext>(m_rParser, std::move(pOldNamespaceMap), true);
+                m_X509IssuerSerials.emplace_back();
+                return std::make_unique<DsX509IssuerSerialContext>(m_rParser, std::move(pOldNamespaceMap), m_X509IssuerSerials.back().first, m_X509IssuerSerials.back().second);
             }
             if (nNamespace == XML_NAMESPACE_DS && rName == "X509Certificate")
             {
-                return std::make_unique<DsX509CertificateContext>(m_rParser, std::move(pOldNamespaceMap));
+                m_X509Certificates.emplace_back();
+                return std::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);
@@ -968,30 +962,20 @@ 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(
@@ -1000,11 +984,11 @@ class XSecParser::XadesCertDigestContext
         {
             if (nNamespace == XML_NAMESPACE_DS && rName == "DigestMethod")
             {
-                return std::make_unique<DsDigestMethodContext>(m_rParser, std::move(pOldNamespaceMap), m_nReferenceDigestID);
+                return std::make_unique<DsDigestMethodContext>(m_rParser, std::move(pOldNamespaceMap), m_rReferenceDigestID);
             }
             if (nNamespace == XML_NAMESPACE_DS && rName == "DigestValue")
             {
-                return std::make_unique<DsDigestValueContext>(m_rParser, std::move(pOldNamespaceMap), m_Value);
+                return std::make_unique<DsDigestValueContext>(m_rParser, std::move(pOldNamespaceMap), m_rDigestValue);
             }
             return XSecParser::Context::CreateChildContext(std::move(pOldNamespaceMap), nNamespace, rName);
         }
@@ -1013,6 +997,12 @@ 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,
@@ -1021,17 +1011,29 @@ 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 std::make_unique<XadesCertDigestContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return std::make_unique<XadesCertDigestContext>(m_rParser, std::move(pOldNamespaceMap), m_CertDigest, m_nReferenceDigestID);
             }
             if (nNamespace == XML_NAMESPACE_XADES132 && rName == "IssuerSerial")
             {
-                return std::make_unique<DsX509IssuerSerialContext>(m_rParser, std::move(pOldNamespaceMap), m_isReferenced);
+                return std::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 edd31b4f29ee..f2e349a94ef6 100644
--- a/xmlsecurity/source/helper/xsecsign.cxx
+++ b/xmlsecurity/source/helper/xsecsign.cxx
@@ -197,6 +197,7 @@ 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,
@@ -210,10 +211,13 @@ 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;
         isi.signatureInfor.eAlgorithmID = eAlgorithmID;
         m_vInternalSignatureInformations.push_back( isi );
     }
@@ -221,16 +225,19 @@ void XSecController::setX509Certificate(
     {
         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)
 {
@@ -241,16 +248,17 @@ 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 1c06a36bf7cb..503bae24d379 100644
--- a/xmlsecurity/source/helper/xsecverify.cxx
+++ b/xmlsecurity/source/helper/xsecverify.cxx
@@ -22,6 +22,7 @@
 #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>
@@ -242,7 +243,9 @@ void XSecController::setReferenceCount() const
     }
 }
 
-void XSecController::setX509IssuerName( OUString const & ouX509IssuerName )
+void XSecController::setX509Data(
+        std::vector<std::pair<OUString, OUString>> & rX509IssuerSerials,
+        std::vector<OUString> const& rX509Certificates)
 {
     if (m_vInternalSignatureInformations.empty())
     {
@@ -250,29 +253,52 @@ void XSecController::setX509IssuerName( OUString const & ouX509IssuerName )
         return;
     }
     InternalSignatureInformation &isi = m_vInternalSignatureInformations.back();
-    isi.signatureInfor.ouX509IssuerName = ouX509IssuerName;
-}
-
-void XSecController::setX509SerialNumber( OUString const & 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(),
+                [&](auto 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 const & 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 const & ouSignatureValue )
@@ -382,13 +408,67 @@ 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");
+    }
 }
 
 namespace {
diff --git a/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx b/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
index d213f21631f5..062b91387cba 100644
--- a/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
+++ b/xmlsecurity/source/xmlsec/mscrypt/x509certificate_mscryptimpl.cxx
@@ -25,6 +25,7 @@
 #include <cppuhelper/supportsservice.hxx>
 #include "x509certificate_mscryptimpl.hxx"
 #include <certificateextension_xmlsecimpl.hxx>
+#include <biginteger.hxx>
 #include "sanextension_mscryptimpl.hxx"
 
 #include "oid.hxx"
@@ -668,4 +669,50 @@ Sequence<OUString> SAL_CALL X509Certificate_MSCryptImpl::getSupportedServiceName
     return { OUString() };
 }
 
+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 dfa9c4ad494b..6b16efd46752 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>
@@ -250,6 +251,7 @@ 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 0cf8c17d3303..332f9363f4dd 100644
--- a/xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx
+++ b/xmlsecurity/source/xmlsec/nss/x509certificate_nssimpl.cxx
@@ -32,6 +32,7 @@
 #include <rtl/ref.hxx>
 #include "x509certificate_nssimpl.hxx"
 
+#include <biginteger.hxx>
 #include <certificateextension_xmlsecimpl.hxx>
 
 #include "sanextension_nssimpl.hxx"
@@ -523,4 +524,28 @@ sal_Bool SAL_CALL X509Certificate_NssImpl::supportsService(const OUString& servi
 /* XServiceInfo */
 Sequence<OUString> SAL_CALL X509Certificate_NssImpl::getSupportedServiceNames() { return { OUString() }; }
 
+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 f4b1364f52dd..85058a273814 100644
--- a/xmlsecurity/source/xmlsec/nss/xmlsignature_nssimpl.cxx
+++ b/xmlsecurity/source/xmlsec/nss/xmlsignature_nssimpl.cxx
@@ -28,6 +28,9 @@
 #include "securityenvironment_nssimpl.hxx"
 
 #include <xmlsec-wrapper.h>
+
+#include <sal/log.hxx>
+
 #include <com/sun/star/xml/crypto/XXMLSignature.hpp>
 
 using namespace ::com::sun::star;
@@ -258,6 +261,7 @@ 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)
         {