Python 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. Chilkat2-Python

import sys
import chilkat2

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 = chilkat2.Cert()
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
if (success == False):
    print(cert.LastErrorText)
    sys.exit()

pdf = chilkat2.Pdf()
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.UserPassword = "user-secret"
pdf.OwnerPassword = "owner-secret"
json = chilkat2.JsonObject()
json.UpdateBool("permissions.modify",False)
jsonOut = chilkat2.JsonObject()
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 = chilkat2.JsonObject()
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 = chilkat2.Pdf()
check.UserPassword = "user-secret"
success = check.LoadFile("qa_output/memo_encrypted_signed.pdf")
if (success == False):
    print(check.LastErrorText)
    sys.exit()

empty = chilkat2.JsonObject()
info = chilkat2.JsonObject()
success = check.Protection("getInfo",empty,info)
if (success == False):
    print(check.LastErrorText)
    sys.exit()

print("algorithm: " + info.StringOf("loaded.algorithm"))
print("signatures: " + str(check.NumSignatures))
sigInfo = chilkat2.JsonObject()
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 = chilkat2.Pdf()
owner.UserPassword = "user-secret"
owner.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 = chilkat2.Pdf()
twice.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.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