Tcl Requires Chilkat v11.7.0+

Choose the PDF Encryption Algorithm: AES-256, AES-128 or RC4

Demonstrates the algorithmChoice option of the encrypt operation. aes-256 is the default and the one to use unless an older reader must open the file. aes-128 is for readers that predate AES-256. rc4-128 and rc4-40 are broken ciphers kept only for very old readers. Each algorithm needs a minimum PDF version, and the file header is raised to it when the PDF is saved, never lowered. A PDF saved with RC4 is written with a classic cross-reference table so that those old readers can parse it.

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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 json [new_CkJsonObject]

set jsonOut [new_CkJsonObject]

set info [new_CkJsonObject]

#  AES-256, the default.  Saved as PDF 1.7 with Adobe extension level 8.
set pdf1 [new_CkPdf]

set success [CkPdf_LoadFile $pdf1 "qa_data/pdf/two_page_memo.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf1]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    exit
}

CkPdf_put_UserPassword $pdf1 "user-secret"
CkPdf_put_OwnerPassword $pdf1 "owner-secret"
CkJsonObject_UpdateString $json "algorithmChoice" "aes-256"
set success [CkPdf_Protection $pdf1 "encrypt" $json $jsonOut]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf1]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    exit
}

puts "aes-256 will be saved as PDF [CkJsonObject_stringOf $jsonOut pending.pdfVersion], Adobe extension level [CkJsonObject_IntOf $jsonOut pending.adobeExtensionLevel]"
set success [CkPdf_WriteFile $pdf1 "qa_output/memo_aes256.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf1]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    exit
}

set success [CkPdf_PreLoadCheck $pdf1 "qa_output/memo_aes256.pdf" $info]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf1]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    exit
}

puts "  saved file: [CkJsonObject_stringOf $info algorithm], PDF [CkJsonObject_stringOf $info pdfVersion]"

#  AES-128, for readers that predate AES-256.  Saved as PDF 1.6.
set pdf2 [new_CkPdf]

set success [CkPdf_LoadFile $pdf2 "qa_data/pdf/two_page_memo.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf2]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    exit
}

CkPdf_put_UserPassword $pdf2 "user-secret"
CkPdf_put_OwnerPassword $pdf2 "owner-secret"
CkJsonObject_UpdateString $json "algorithmChoice" "aes-128"
set success [CkPdf_Protection $pdf2 "encrypt" $json $jsonOut]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf2]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    exit
}

puts "aes-128 will be saved as PDF [CkJsonObject_stringOf $jsonOut pending.pdfVersion]"
set success [CkPdf_WriteFile $pdf2 "qa_output/memo_aes128.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf2]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    exit
}

set success [CkPdf_PreLoadCheck $pdf2 "qa_output/memo_aes128.pdf" $info]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf2]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    exit
}

puts "  saved file: [CkJsonObject_stringOf $info algorithm], PDF [CkJsonObject_stringOf $info pdfVersion]"

#  RC4-128, a broken cipher, only for readers too old for AES.  Saved as PDF 1.4.
set pdf3 [new_CkPdf]

set success [CkPdf_LoadFile $pdf3 "qa_data/pdf/two_page_memo.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf3]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    delete_CkPdf $pdf3
    exit
}

CkPdf_put_UserPassword $pdf3 "user-secret"
CkPdf_put_OwnerPassword $pdf3 "owner-secret"
CkJsonObject_UpdateString $json "algorithmChoice" "rc4-128"
set success [CkPdf_Protection $pdf3 "encrypt" $json $jsonOut]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf3]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    delete_CkPdf $pdf3
    exit
}

puts "rc4-128 will be saved as PDF [CkJsonObject_stringOf $jsonOut pending.pdfVersion]"
set success [CkPdf_WriteFile $pdf3 "qa_output/memo_rc4_128.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf3]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    delete_CkPdf $pdf3
    exit
}

set success [CkPdf_PreLoadCheck $pdf3 "qa_output/memo_rc4_128.pdf" $info]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf3]
    delete_CkJsonObject $json
    delete_CkJsonObject $jsonOut
    delete_CkJsonObject $info
    delete_CkPdf $pdf1
    delete_CkPdf $pdf2
    delete_CkPdf $pdf3
    exit
}

puts "  saved file: [CkJsonObject_stringOf $info algorithm], PDF [CkJsonObject_stringOf $info pdfVersion]"

#  Sample output:

#  aes-256 will be saved as PDF 1.7, Adobe extension level 8
#    saved file: aes-256, PDF 1.7
#  aes-128 will be saved as PDF 1.6
#    saved file: aes-128, PDF 1.6
#  rc4-128 will be saved as PDF 1.4
#    saved file: rc4-128, PDF 1.4

delete_CkJsonObject $json
delete_CkJsonObject $jsonOut
delete_CkJsonObject $info
delete_CkPdf $pdf1
delete_CkPdf $pdf2
delete_CkPdf $pdf3