(VB.NET) JWE with Binary Data

Demonstrates how to create a JWE that contains a binary payload (such as a JPG image).

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

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' 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.

Dim success As Boolean

' Load a JPG file that will be the JWE payload.
Dim jpgBytes As New Chilkat.BinData
success = jpgBytes.LoadFile("qa_data/jpg/starfish.jpg")
' Make sure your app checks the success/failure of the call to LoadFile..
Debug.WriteLine("Original JPG size = " & jpgBytes.NumBytes)

Dim jwe As New Chilkat.Jwe

Dim jweProtHdr As New Chilkat.JsonObject
jweProtHdr.AppendString("alg","A128KW")
jweProtHdr.AppendString("enc","A128CBC-HS256")
jwe.SetProtectedHeader(jweProtHdr)

Dim aesWrappingKey As String = "GawgguFyGrWKav7AX4VKUg"
jwe.SetWrappingKey(0,aesWrappingKey,"base64url")

' Encrypt and return the JWE in sbJwe:
Dim sbJwe As New Chilkat.StringBuilder
success = jwe.EncryptBd(jpgBytes,sbJwe)
If (success <> True) Then
    Debug.WriteLine(jwe.LastErrorText)
    Exit Sub
End If


' Show the JWE:
Debug.WriteLine(sbJwe.GetAsString())
Debug.WriteLine("size of JWE: " & sbJwe.Length)

' ---------------------------------------------------------
' Decrypt to get the original JPG file..

Dim jwe2 As New Chilkat.Jwe
success = jwe2.LoadJweSb(sbJwe)
If (success <> True) Then
    Debug.WriteLine(jwe2.LastErrorText)
    Exit Sub
End If

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

' Decrypt.
Dim jpgOriginal As New Chilkat.BinData
success = jwe2.DecryptBd(0,jpgOriginal)
If (success <> True) Then
    Debug.WriteLine(jwe2.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("Decrypted JPG size = " & jpgOriginal.NumBytes)

' Save the decrypted JPG to a file.
success = jpgOriginal.WriteFile("qa_output/jwe_decrypted_starfish.jpg")

Debug.WriteLine("success = " & success)

' The output of this program, when tested, was:
' Original JPG size = 6229
' eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.9YFz_wteV ... 7Et3hKhpxnKEXw
' size of JWE: 8473
' Decrypted JPG size = 6229
' success = True