(VBScript) JWE with DEFLATE Compression

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

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

' Note: This example requires Chilkat v9.5.0.66 or greater.

' Create some plaintext to be encrypted.
' This example will demonstrate with and without DEFLATE (zip) compression.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbPlainText = CreateObject("Chilkat.StringBuilder")
bCrLf = 1
line = "Live long and prosper."
success = sbPlainText.AppendLine(line,bCrLf)
success = sbPlainText.AppendLine(line,bCrLf)
success = sbPlainText.AppendLine(line,bCrLf)
success = sbPlainText.AppendLine(line,bCrLf)

' The text to be encrypted:
outFile.WriteLine(sbPlainText.GetAsString())

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Jwe")
set jwe = CreateObject("Chilkat.Jwe")

' Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
' The "zip":"DEF" parameter indicates that the plaintext payload should
' be compressed prior to encryption.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.JsonObject")
set jweProtHdr = CreateObject("Chilkat.JsonObject")
success = jweProtHdr.AppendString("alg","A128KW")
success = jweProtHdr.AppendString("enc","A128CBC-HS256")
success = jweProtHdr.AppendString("zip","DEF")
success = jwe.SetProtectedHeader(jweProtHdr)

' Set the AES key wrap key:
aesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
success = jwe.SetWrappingKey(0,aesWrappingKey,"base64url")

' Encrypt and return the JWE in sbJweCompressed:
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbJweCompressed = CreateObject("Chilkat.StringBuilder")
success = jwe.EncryptSb(sbPlainText,"utf-8",sbJweCompressed)
If (success <> 1) Then
    outFile.WriteLine(jwe.LastErrorText)
    WScript.Quit
End If

' Show the compressed JWE:
outFile.WriteLine(sbJweCompressed.GetAsString())
outFile.WriteLine("size of compressed JWE: " & sbJweCompressed.Length)

' Now create a JWE without compression.
success = jweProtHdr.Delete("zip")
' Make sure to update the shared protected header:
success = jwe.SetProtectedHeader(jweProtHdr)

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbJweUncompressed = CreateObject("Chilkat.StringBuilder")
success = jwe.EncryptSb(sbPlainText,"utf-8",sbJweUncompressed)
If (success <> 1) Then
    outFile.WriteLine(jwe.LastErrorText)
    WScript.Quit
End If

' Show the uncompressed JWE:
outFile.WriteLine(sbJweUncompressed.GetAsString())
outFile.WriteLine("size of uncompressed JWE: " & sbJweUncompressed.Length)

' Decrypting is the same whether compression is used or not.
' The "zip" header in the JWE indicates that the payload should be 
' automatically decompressed (inflated) after decrypting.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Jwe")
set jwe2 = CreateObject("Chilkat.Jwe")
success = jwe2.LoadJweSb(sbJweCompressed)
If (success <> 1) Then
    outFile.WriteLine(jwe2.LastErrorText)
    WScript.Quit
End If

' Set the AES wrap key.
success = jwe2.SetWrappingKey(0,aesWrappingKey,"base64url")

' Decrypt (also automatically decompresses).
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbOriginalText = CreateObject("Chilkat.StringBuilder")
success = jwe2.DecryptSb(0,"utf-8",sbOriginalText)
If (success <> 1) Then
    outFile.WriteLine(jwe2.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("original text from compressed JWE: ")
outFile.WriteLine(sbOriginalText.GetAsString())

' -----------------------------------------------------------
' Do the same with the uncompressed JWE

success = jwe2.LoadJweSb(sbJweUncompressed)
If (success <> 1) Then
    outFile.WriteLine(jwe2.LastErrorText)
    WScript.Quit
End If

' Set the AES wrap key.
success = jwe2.SetWrappingKey(0,aesWrappingKey,"base64url")

' Decrypt.
sbOriginalText.Clear 
success = jwe2.DecryptSb(0,"utf-8",sbOriginalText)
If (success <> 1) Then
    outFile.WriteLine(jwe2.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("original text from uncompressed JWE: ")
outFile.WriteLine(sbOriginalText.GetAsString())

' ------------------------------------------------
' The output of this example is:
' (Note: Your output data will be different because the content encryption key is randomly generated.)

' eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
' size of compressed JWE: 212
' eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
' size of uncompressed JWE: 303
' original text from compressed JWE: 
' Live long and prosper.
' Live long and prosper.
' Live long and prosper.
' Live long and prosper.
' 
' original text from uncompressed JWE: 
' Live long and prosper.
' Live long and prosper.
' Live long and prosper.
' Live long and prosper.
' 

outFile.Close