(Chilkat2-Python) 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

Chilkat2 Python Downloads

install with pip
pip3 install chilkat2
or download... Python Module for Windows, Linux, Alpine Linux, MacOS, Solaris

import sys
import chilkat2

# 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).
sbXmlToZip = chilkat2.StringBuilder()
success = sbXmlToZip.LoadFile("qa_data/xml/PIT-11Z.xml","utf-8")
if (success != True):
    print("Failed to load the XML to be zipped.")
    sys.exit()

zip = chilkat2.Zip()

# Initialize the zip object. No file is created in this call.
# It should always return True.
success = zip.NewZip("PIT-11Z.zip")

# Add the XML to be zipped.
# entry is a CkZipEntry
entry = zip.AppendString("PIT-11Z.xml",sbXmlToZip.GetAsString())

# Write the zip to a BinData object.
bdZip = chilkat2.BinData()
zip.WriteBd(bdZip)
# The contents of the bdZip will be retrieved in base64 format when needed below..

gen = chilkat2.XmlDSigGen()

gen.SigLocation = ""
gen.SigLocationMod = 0

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

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

# Create an Object to be added to the Signature.
object1 = chilkat2.Xml()
object1.Tag = "xades:QualifyingProperties"
object1.AddAttribute("xmlns:xades","http://uri.etsi.org/01903/v1.3.2#")
object1.AddAttribute("Id","QualifyingProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_43")
object1.AddAttribute("Target","#Signature_2a8df7f8-b958-40cc-83f6-edb53b837347_19")
object1.UpdateAttrAt("xades:SignedProperties",True,"Id","SignedProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_4e")
object1.UpdateAttrAt("xades:SignedProperties|xades:SignedSignatureProperties",True,"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.
object1.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
object1.UpdateAttrAt("xades:SignedProperties|xades:SignedSignatureProperties|xades:SigningCertificateV2|xades:Cert|xades:CertDigest|ds:DigestMethod",True,"Algorithm","http://www.w3.org/2000/09/xmldsig#sha1")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedSignatureProperties|xades:SigningCertificateV2|xades:Cert|xades:CertDigest|ds:DigestValue","TO BE GENERATED BY CHILKAT")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedSignatureProperties|xades:SigningCertificateV2|xades:Cert|xades:IssuerSerialV2","TO BE GENERATED BY CHILKAT")
object1.UpdateAttrAt("xades:SignedProperties|xades:SignedDataObjectProperties",True,"Id","SignedDataObjectProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_4b")
object1.UpdateAttrAt("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat",True,"ObjectReference","#Reference1_2a8df7f8-b958-40cc-83f6-edb53b837347_27")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:Description","MIME-Version: 1.0\r\nContent-Type: application/zip\r\nContent-Transfer-Encoding: binary\r\nContent-Disposition: filename=&quot;PIT-11Z.zip&quot;")
object1.UpdateAttrAt("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:ObjectIdentifier|xades:Identifier",True,"Qualifier","OIDAsURI")
object1.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")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:ObjectIdentifier|xades:Description","Opis formatu dokumentu oraz jego pelna nazwa")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:ObjectIdentifier|xades:DocumentationReferences|xades:DocumentationReference","http://www.certum.pl/OIDAsURI/signedFile.pdf")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:DataObjectFormat|xades:MimeType","application/zip")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:CommitmentTypeIndication|xades:CommitmentTypeId|xades:Identifier","http://uri.etsi.org/01903/v1.2.2#ProofOfApproval")
object1.UpdateChildContent("xades:SignedProperties|xades:SignedDataObjectProperties|xades:CommitmentTypeIndication|xades:AllSignedDataObjects","")
object1.UpdateAttrAt("xades:UnsignedProperties",True,"Id","UnsignedProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_55")

# Emit XML in compact (single-line) format to avoid whitespace problems.
object1.EmitCompact = True
gen.AddObject("",object1.GetXml(),"","")

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

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

# -------- Reference 2 --------
gen.AddObjectRef("SignedProperties_2a8df7f8-b958-40cc-83f6-edb53b837347_4e","sha1","","","http://uri.etsi.org/01903#SignedProperties")
gen.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)
cert = chilkat2.Cert()
success = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123")
if (success != True):
    print(cert.LastErrorText)
    sys.exit()

gen.SetX509Cert(cert,True)

gen.KeyInfoType = "X509Data"
gen.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.
sbXml = chilkat2.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.)
gen.Behaviors = "AttributeSortingBug,CompactSignedXml"

# Sign the XML...
success = gen.CreateXmlDSigSb(sbXml)
if (success != True):
    print(gen.LastErrorText)
    sys.exit()

# -----------------------------------------------

# Save the signed XML to a file.
success = sbXml.WriteFile("qa_output/signedXml.xml","utf-8",False)

print(sbXml.GetAsString())

# ----------------------------------------
# Verify the signature we just produced...
verifier = chilkat2.XmlDSig()
success = verifier.LoadSignatureSb(sbXml)
if (success != True):
    print(verifier.LastErrorText)
    sys.exit()

verified = verifier.VerifySignature(True)
if (verified != True):
    print(verifier.LastErrorText)
    sys.exit()

print("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.
xml = chilkat2.Xml()
xml.LoadSb(sbXml,True)

# 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.)
strZipBase64 = xml.GetChildContent("ds:Object[1]")

bdZip.Clear()
bdZip.AppendEncoded(strZipBase64,"base64")
if (bdZip.NumBytes == 0):
    print("Something went wrong.. we dont' have any data..")
    sys.exit()

success = zip.OpenBd(bdZip)
if (success != True):
    print(zip.LastErrorText)
    sys.exit()

# Get the 1st file in the zip, which should be the PIT-11Z.xml
# entry is a CkZipEntry
entry = zip.GetEntryByIndex(0)
if (zip.LastMethodSuccess != True):
    print("Zip contains no files...")
    sys.exit()

# Get the XML:
origXml = entry.UnzipToString(0,"utf-8")
print("Original XML extracted from base64 zip:")
print(origXml)