Tcl Requires Chilkat v11.7.0+

Password-Protect a PDF with AES-256 Encryption

See more PDF Protection Examples

Demonstrates the simplest way to encrypt a PDF so that it needs a password to open. The passwords come from the UserPassword and OwnerPassword properties, and Protection with the encrypt operation and an empty JSON uses the defaults: AES-256, everything encrypted, every permission granted. Protection only records the security the PDF will be saved with. Nothing is encrypted until WriteFile is called. Tcl

load ./chilkat.dll

set success 0

#  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

set pdf [new_CkPdf]

set success [CkPdf_LoadFile $pdf "qa_data/pdf/two_page_memo.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf]
    delete_CkPdf $pdf
    exit
}

#  The passwords are taken from these two properties at the time Protection is called.
#  The user password opens the PDF.  The owner password opens it too, and is the one needed
#  later to change or remove the protection.
CkPdf_put_UserPassword $pdf "user-secret"
CkPdf_put_OwnerPassword $pdf "owner-secret"

#  An empty JSON asks for the defaults: AES-256, everything encrypted, every permission granted.
set json [new_CkJsonObject]

set jsonOut [new_CkJsonObject]

set success [CkPdf_Protection $pdf "encrypt" $json $jsonOut]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    exit
}

#  Nothing has been encrypted yet.  "pending" describes the security the PDF will be saved with.
puts "algorithm: [CkJsonObject_stringOf $jsonOut pending.algorithm]"
puts "PDF version: [CkJsonObject_stringOf $jsonOut pending.pdfVersion]"
puts "password needed to open: [CkJsonObject_BoolOf $jsonOut pending.userPasswordRequired]"

#  Writing the file applies it.
set success [CkPdf_WriteFile $pdf "qa_output/memo_encrypted.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    exit
}

#  PreLoadCheck reports a file's encryption without loading it, and needs no password.
set checker [new_CkPdf]

set info [new_CkJsonObject]

set success [CkPdf_PreLoadCheck $checker "qa_output/memo_encrypted.pdf" $info]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $checker]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkPdf $checker
    delete_CkJsonObject $info
    exit
}

puts "encrypted: [CkJsonObject_BoolOf $info encrypted]"
puts "openPasswordRequired: [CkJsonObject_BoolOf $info openPasswordRequired]"

#  With the password, the PDF opens normally.
set reader [new_CkPdf]

CkPdf_put_UserPassword $reader "user-secret"
set success [CkPdf_LoadFile $reader "qa_output/memo_encrypted.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $reader]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkPdf $checker
    delete_CkJsonObject $info
    delete_CkPdf $reader
    exit
}

puts "pages: [CkPdf_get_NumPages $reader]"

#  Sample output:

#  algorithm: aes-256
#  PDF version: 1.7
#  password needed to open: True
#  encrypted: True
#  openPasswordRequired: True
#  pages: 2

delete_CkPdf $pdf
delete_CkJsonObject $json
delete_CkJsonObject $jsonOut
delete_CkPdf $checker
delete_CkJsonObject $info
delete_CkPdf $reader