(Visual FoxPro) Signed Zip as Base64 with XAdES-BES

This example is to help companies implement a solution for sending XAdES-BES to the Polish government for reporting purposes. Specifically:

Przed podpisaniem deklaracja zbiorcza (PIT-11Z, PIT-8CZ, PIT-40Z, PIT-RZ) musi zostać
umieszczona w archiwum ZIP. W tym przypadku, podpisywany jest plik archiwum ZIP,
przyjmujący w podpisie XAdES-BES formę zakodowaną base64.

The example demonstrates the following:

Zip an XML file (PIT-11Z.xml is zipped to PIT-11Z.zip)
Create XML to be signed, where the XML contains the base64 encoded content of the PIT-11Z.zip archive.
XAdES-BES sign the XML containing the base64 zip.

This example will also show the reverse:

Verify the signed XML.
Extract the PIT-11z.zip from the signed XML.
Unzip the PIT-11Z.zip to get the original PIT-11Z.xml

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loSbXmlToZip
LOCAL loZip
LOCAL loBdZip
LOCAL loGen
LOCAL loObject1
LOCAL loCert
LOCAL loSbXml
LOCAL loVerifier
LOCAL lnVerified
LOCAL loXml
LOCAL lcStrZipBase64
LOCAL loEntry
LOCAL lcOrigXml

lnSuccess = 0

* This example assumes the Chilkat API to have been previously unlocked.
* See Global Unlock Sample for sample code.

* Zip the PIT-11Z.xml to create PIT-11Z.zip (not as a .zip file, but in-memory).
loSbXmlToZip = CreateObject('Chilkat.StringBuilder')
lnSuccess = loSbXmlToZip.LoadFile("qa_data/xml/PIT-11Z.xml","utf-8")
IF (lnSuccess <> 1) THEN
    ? "Failed to load the XML to be zipped."
    RELEASE loSbXmlToZip
    CANCEL
ENDIF

loZip = CreateObject('Chilkat.Zip')

* Initialize the zip object. No file is created in this call.
* It should always return 1.
lnSuccess = loZip.NewZip("PIT-11Z.zip")

* Add the XML to be zipped.
loZip.AddSb("PIT-11Z.xml",loSbXmlToZip,"utf-8")

* Write the zip to a BinData object.
loBdZip = CreateObject('Chilkat.BinData')
loZip.WriteBd(loBdZip)
* The contents of the bdZip will be retrieved in base64 format when needed below..

loGen = CreateObject('Chilkat.XmlDSigGen')

loGen.SigLocation = ""
loGen.SigLocationMod = 0

loGen.SigId = "Signature_2a8df7f8-b958-40cc-83f6-edb53b837347_19"
loGen.SigNamespacePrefix = "ds"
loGen.SigNamespaceUri = "http://www.w3.org/2000/09/xmldsig#"
loGen.SigValueId = "SignatureValue_2a8df7f8-b958-40cc-83f6-edb53b837347_52"
loGen.SignedInfoId = "SignedInfo_2a8df7f8-b958-40cc-83f6-edb53b837347_41"
loGen.SignedInfoCanonAlg = "C14N"
loGen.SignedInfoDigestMethod = "sha1"

* Set the KeyInfoId before adding references..
loGen.KeyInfoId = "KeyInfo_2a8df7f8-b958-40cc-83f6-edb53b837347_24"

* Create an Object to be added to the Signature.
loObject1 = CreateObject('Chilkat.Xml')
loObject1.Tag = "xades:QualifyingProperties"
loObject1.AddAttribute("xmlns:xades","http://uri.etsi.org/01903/v1.3.2#")
loObject1.AddAttribute("Id","QualifyingProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_43")
loObject1.AddAttribute("Target","#Signature_2a8df7f8-b958-40cc-83f6-edb53b837347_19")
loObject1.UpdateAttrAt("xades:SignedProperties",1,"Id","SignedProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_4e")
loObject1.UpdateAttrAt("xades:SignedProperties|xades:SignedSignatureProperties",1,"Id","SignedSignatureProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_0a")
* Chilkat will replace the strings "TO BE GENERATED BY CHILKAT" with actual values when the signature is created.
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedSignatureProperties|xades:SigningTime","TO BE GENERATED BY CHILKAT")
* Note: It may be that http://www.w3.org/2001/04/xmlenc#sha256 is needed in the following line instead of http://www.w3.org/2000/09/xmldsig#sha1
loObject1.UpdateAttrAt("xades:SignedProperties|xades:SignedSignatureProperties|xades:SigningCertificateV2|xades:Cert|xades:CertDigest|ds:DigestMethod",1,"Algorithm","http://www.w3.org/2000/09/xmldsig#sha1")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedSignatureProperties|xades:SigningCertificateV2|xades:Cert|xades:CertDigest|ds:DigestValue","TO BE GENERATED BY CHILKAT")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedSignatureProperties|xades:SigningCertificateV2|xades:Cert|xades:IssuerSerialV2","TO BE GENERATED BY CHILKAT")
loObject1.UpdateAttrAt("xades:SignedProperties|xades:SignedDataObjectProperties",1,"Id","SignedDataObjectProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_4b")
loObject1.UpdateAttrAt("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat",1,"ObjectReference","#Reference1_2a8df7f8-b958-40cc-83f6-edb53b837347_27")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:Description","MIME-Version: 1.0" + CHR(13) + CHR(10) + "Content-Type: application/zip" + CHR(13) + CHR(10) + "Content-Transfer-Encoding: binary" + CHR(13) + CHR(10) + "Content-Disposition: filename=&quot;PIT-11Z.zip&quot;")
loObject1.UpdateAttrAt("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:ObjectIdentifier|xades:Identifier",1,"Qualifier","OIDAsURI")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:ObjectIdentifier|xades:Identifier","http://www.certum.pl/OIDAsURI/signedFile/1.2.616.1.113527.3.1.1.3.1")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:ObjectIdentifier|xades:Description","Opis formatu dokumentu oraz jego pelna nazwa")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:ObjectIdentifier|xades:DocumentationReferences|xades:DocumentationReference","http://www.certum.pl/OIDAsURI/signedFile.pdf")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:MimeType","application/zip")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:CommitmentTypeIndication|xades:CommitmentTypeId|xades:Identifier","http://uri.etsi.org/01903/v1.2.2#ProofOfApproval")
loObject1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:CommitmentTypeIndication|xades:AllSignedDataObjects","")
loObject1.UpdateAttrAt("xades:UnsignedProperties",1,"Id","UnsignedProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_55")

* Emit XML in compact (single-line) format to avoid whitespace problems.
loObject1.EmitCompact = 1
loGen.AddObject("",loObject1.GetXml(),"","")

* Create an Object to be added to the Signature.
* This is where we add the base64 representation of the PIT-11Z.zip
loGen.AddObject("Object1_2a8df7f8-b958-40cc-83f6-edb53b837347",loBdZip.GetEncoded("base64"),"","http://www.w3.org/2000/09/xmldsig#base64")

* -------- Reference 1 --------
loGen.AddObjectRef("Object1_2a8df7f8-b958-40cc-83f6-edb53b837347","sha1","C14N_WithComments","","")
loGen.SetRefIdAttr("Object1_2a8df7f8-b958-40cc-83f6-edb53b837347","Reference1_2a8df7f8-b958-40cc-83f6-edb53b837347_27")

* -------- Reference 2 --------
loGen.AddObjectRef("SignedProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_4e","sha1","","","http://uri.etsi.org/01903#SignedProperties")
loGen.SetRefIdAttr("SignedProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_4e","SignedProperties-Reference_2a8df7f8-b958-40cc-83f6-edb53b837347_28")

* Provide a certificate + private key. (PFX password is test123)
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loSbXmlToZip
    RELEASE loZip
    RELEASE loBdZip
    RELEASE loGen
    RELEASE loObject1
    RELEASE loCert
    CANCEL
ENDIF

loGen.SetX509Cert(loCert,1)

loGen.KeyInfoType = "X509Data"
loGen.X509Type = "Certificate"

* This will be an enveloping signature where the Signature element
* is the XML document root, the signed data is contained within Object
* tag(s) within the Signature.
* Therefore, pass an empty sbXml to CreateXmlDsigSb.
loSbXml = CreateObject('Chilkat.StringBuilder')

* The Polish government's XmlDSig implementation requires that we reproduce an attribute-sorting error.
* (This is an error in the XML canonicalization that is not noticed when both the signature-creation code and signature-verification code use
* the same XML canonicalization implementation w/ the bug.)
loGen.Behaviors = "AttributeSortingBug,CompactSignedXml"

* Sign the XML...
lnSuccess = loGen.CreateXmlDSigSb(loSbXml)
IF (lnSuccess = 0) THEN
    ? loGen.LastErrorText
    RELEASE loSbXmlToZip
    RELEASE loZip
    RELEASE loBdZip
    RELEASE loGen
    RELEASE loObject1
    RELEASE loCert
    RELEASE loSbXml
    CANCEL
ENDIF

* -----------------------------------------------

* Save the signed XML to a file.
lnSuccess = loSbXml.WriteFile("qa_output/signedXml.xml","utf-8",0)

? loSbXml.GetAsString()

* ----------------------------------------
* Verify the signature we just produced...
loVerifier = CreateObject('Chilkat.XmlDSig')
lnSuccess = loVerifier.LoadSignatureSb(loSbXml)
IF (lnSuccess = 0) THEN
    ? loVerifier.LastErrorText
    RELEASE loSbXmlToZip
    RELEASE loZip
    RELEASE loBdZip
    RELEASE loGen
    RELEASE loObject1
    RELEASE loCert
    RELEASE loSbXml
    RELEASE loVerifier
    CANCEL
ENDIF

lnVerified = loVerifier.VerifySignature(1)
IF (lnVerified <> 1) THEN
    ? loVerifier.LastErrorText
    RELEASE loSbXmlToZip
    RELEASE loZip
    RELEASE loBdZip
    RELEASE loGen
    RELEASE loObject1
    RELEASE loCert
    RELEASE loSbXml
    RELEASE loVerifier
    CANCEL
ENDIF

? "This signature was successfully verified."

* ------------------------------------
* Finally, let's extract the .zip from the signed XML, and then unzip the original PIT-11Z.xml from the in-memory zip.
loXml = CreateObject('Chilkat.Xml')
loXml.LoadSb(loSbXml,1)

* The base64 image of the PIT-11Z.zip is in the 2nd ds:Object child of the ds:Signature (the ds:Signature is the root element of the signed XML).
* (ds:Object[0] would be the 1st ds:Object child.  Index 1 is the 2nd ds:Object child.)
lcStrZipBase64 = loXml.GetChildContent("ds:Object[1]")

loBdZip.Clear()
loBdZip.AppendEncoded(lcStrZipBase64,"base64")
IF (loBdZip.NumBytes = 0) THEN
    ? "Something went wrong.. we dont' have any data.."
    RELEASE loSbXmlToZip
    RELEASE loZip
    RELEASE loBdZip
    RELEASE loGen
    RELEASE loObject1
    RELEASE loCert
    RELEASE loSbXml
    RELEASE loVerifier
    RELEASE loXml
    CANCEL
ENDIF

lnSuccess = loZip.OpenBd(loBdZip)
IF (lnSuccess = 0) THEN
    ? loZip.LastErrorText
    RELEASE loSbXmlToZip
    RELEASE loZip
    RELEASE loBdZip
    RELEASE loGen
    RELEASE loObject1
    RELEASE loCert
    RELEASE loSbXml
    RELEASE loVerifier
    RELEASE loXml
    CANCEL
ENDIF

* Get the 1st file in the zip, which should be the PIT-11Z.xml
loEntry = CreateObject('Chilkat.ZipEntry')
lnSuccess = loZip.EntryAt(0,loEntry)
IF (lnSuccess = 0) THEN
    ? "Zip contains no files..."
    RELEASE loSbXmlToZip
    RELEASE loZip
    RELEASE loBdZip
    RELEASE loGen
    RELEASE loObject1
    RELEASE loCert
    RELEASE loSbXml
    RELEASE loVerifier
    RELEASE loXml
    RELEASE loEntry
    CANCEL
ENDIF

* Get the XML:
lcOrigXml = loEntry.UnzipToString(0,"utf-8")
? "Original XML extracted from base64 zip:"
? lcOrigXml

RELEASE loSbXmlToZip
RELEASE loZip
RELEASE loBdZip
RELEASE loGen
RELEASE loObject1
RELEASE loCert
RELEASE loSbXml
RELEASE loVerifier
RELEASE loXml
RELEASE loEntry