CkPython Requires Chilkat v11.7.0+

Encrypt and Sign a PDF, and Sign an Encrypted PDF

See more PDF Protection Examples

Demonstrates signing together with encryption. A pending encrypt is applied by SignPdf before it signs, so one call produces a PDF that is both encrypted and signed. A PDF that is already encrypted can be signed too, and stays encrypted. When it was opened with only the user password its permissions decide: adding a signature field needs both the modify and the annotate permission. Loading the PDF with its owner password lifts that. CkPython

import sys
import chilkat

success = False

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

#  The PDF used in this example is available at two_page_memo.pdf

#  The signing certificate, with its private key.
cert = chilkat.CkCert()
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
if (success == False):
    print(cert.lastErrorText())
    sys.exit()

pdf = chilkat.CkPdf()
success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf")
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

#  Encrypt with AES-256 and do not permit modifying.
pdf.put_UserPassword("user-secret")
pdf.put_OwnerPassword("owner-secret")
json = chilkat.CkJsonObject()
json.UpdateBool("permissions.modify",False)
jsonOut = chilkat.CkJsonObject()
success = pdf.Protection("encrypt",json,jsonOut)
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

#  The encryption is still pending.  SignPdf applies it first and signs the encrypted result.
success = pdf.SetSigningCert(cert)
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

sigOpts = chilkat.CkJsonObject()
sigOpts.UpdateBool("invisibleSignature",True)
sigOpts.UpdateInt("signingCertificateV2",1)
sigOpts.UpdateInt("signingTime",1)
success = pdf.SignPdf(sigOpts,"qa_output/memo_encrypted_signed.pdf")
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

#  The result is encrypted and signed.
check = chilkat.CkPdf()
check.put_UserPassword("user-secret")
success = check.LoadFile("qa_output/memo_encrypted_signed.pdf")
if (success == False):
    print(check.lastErrorText())
    sys.exit()

empty = chilkat.CkJsonObject()
info = chilkat.CkJsonObject()
success = check.Protection("getInfo",empty,info)
if (success == False):
    print(check.lastErrorText())
    sys.exit()

print("algorithm: " + info.stringOf("loaded.algorithm"))
print("signatures: " + str(check.get_NumSignatures()))
sigInfo = chilkat.CkJsonObject()
verified = check.VerifySignature(0,sigInfo)
print("signature verifies: " + str(verified))

#  Signing an encrypted PDF.  This one was opened with only the user password, and its
#  permissions do not allow modifying, so another signature is refused.
success = check.SetSigningCert(cert)
if (success == False):
    print(check.lastErrorText())
    sys.exit()

success = check.SignPdf(sigOpts,"qa_output/memo_signed_twice.pdf")
if (success == False):
    print("A second signature was refused: the permissions do not allow it.")

#  Loaded with the owner password, the same PDF can be signed.  It stays encrypted, and the
#  first signature stays valid because the new one is added as an incremental update.
owner = chilkat.CkPdf()
owner.put_UserPassword("user-secret")
owner.put_OwnerPassword("owner-secret")
success = owner.LoadFile("qa_output/memo_encrypted_signed.pdf")
if (success == False):
    print(owner.lastErrorText())
    sys.exit()

success = owner.SetSigningCert(cert)
if (success == False):
    print(owner.lastErrorText())
    sys.exit()

success = owner.SignPdf(sigOpts,"qa_output/memo_signed_twice.pdf")
if (success == False):
    print(owner.lastErrorText())
    sys.exit()

twice = chilkat.CkPdf()
twice.put_UserPassword("user-secret")
success = twice.LoadFile("qa_output/memo_signed_twice.pdf")
if (success == False):
    print(twice.lastErrorText())
    sys.exit()

print("signatures after signing with owner rights: " + str(twice.get_NumSignatures()))
verified = twice.VerifySignature(0,sigInfo)
print("first signature still verifies: " + str(verified))
verified = twice.VerifySignature(1,sigInfo)
print("second signature verifies: " + str(verified))

#  Sample output:

#  algorithm: aes-256
#  signatures: 1
#  signature verifies: True
#  A second signature was refused: the permissions do not allow it.
#  signatures after signing with owner rights: 2
#  first signature still verifies: True
#  second signature verifies: True