PureBasic 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. PureBasic

IncludeFile "CkPdf.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    success.i = 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

    pdf.i = CkPdf::ckCreate()
    If pdf.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPdf::ckLoadFile(pdf,"qa_data/pdf/two_page_memo.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        ProcedureReturn
    EndIf

    ;  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::setCkUserPassword(pdf, "user-secret")
    CkPdf::setCkOwnerPassword(pdf, "owner-secret")

    ;  An empty JSON asks for the defaults: AES-256, everything encrypted, every permission granted.
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    jsonOut.i = CkJsonObject::ckCreate()
    If jsonOut.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPdf::ckProtection(pdf,"encrypt",json,jsonOut)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        ProcedureReturn
    EndIf

    ;  Nothing has been encrypted yet.  "pending" describes the security the PDF will be saved with.
    Debug "algorithm: " + CkJsonObject::ckStringOf(jsonOut,"pending.algorithm")
    Debug "PDF version: " + CkJsonObject::ckStringOf(jsonOut,"pending.pdfVersion")
    Debug "password needed to open: " + Str(CkJsonObject::ckBoolOf(jsonOut,"pending.userPasswordRequired"))

    ;  Writing the file applies it.
    success = CkPdf::ckWriteFile(pdf,"qa_output/memo_encrypted.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        ProcedureReturn
    EndIf

    ;  PreLoadCheck reports a file's encryption without loading it, and needs no password.
    checker.i = CkPdf::ckCreate()
    If checker.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    info.i = CkJsonObject::ckCreate()
    If info.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPdf::ckPreLoadCheck(checker,"qa_output/memo_encrypted.pdf",info)
    If success = 0
        Debug CkPdf::ckLastErrorText(checker)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        CkPdf::ckDispose(checker)
        CkJsonObject::ckDispose(info)
        ProcedureReturn
    EndIf

    Debug "encrypted: " + Str(CkJsonObject::ckBoolOf(info,"encrypted"))
    Debug "openPasswordRequired: " + Str(CkJsonObject::ckBoolOf(info,"openPasswordRequired"))

    ;  With the password, the PDF opens normally.
    reader.i = CkPdf::ckCreate()
    If reader.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkPdf::setCkUserPassword(reader, "user-secret")
    success = CkPdf::ckLoadFile(reader,"qa_output/memo_encrypted.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(reader)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        CkPdf::ckDispose(checker)
        CkJsonObject::ckDispose(info)
        CkPdf::ckDispose(reader)
        ProcedureReturn
    EndIf

    Debug "pages: " + Str(CkPdf::ckNumPages(reader))

    ;  Sample output:

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


    CkPdf::ckDispose(pdf)
    CkJsonObject::ckDispose(json)
    CkJsonObject::ckDispose(jsonOut)
    CkPdf::ckDispose(checker)
    CkJsonObject::ckDispose(info)
    CkPdf::ckDispose(reader)


    ProcedureReturn
EndProcedure