(Lianja) 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.

// Load a JPG file that will be the JWE payload.
loJpgBytes = createobject("CkBinData")
llSuccess = loJpgBytes.LoadFile("qa_data/jpg/starfish.jpg")
// Make sure your app checks the success/failure of the call to LoadFile..
? "Original JPG size = " + str(loJpgBytes.NumBytes)

loJwe = createobject("CkJwe")

loJweProtHdr = createobject("CkJsonObject")
loJweProtHdr.AppendString("alg","A128KW")
loJweProtHdr.AppendString("enc","A128CBC-HS256")
loJwe.SetProtectedHeader(loJweProtHdr)

lcAesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
loJwe.SetWrappingKey(0,lcAesWrappingKey,"base64url")

// Encrypt and return the JWE in sbJwe:
loSbJwe = createobject("CkStringBuilder")
llSuccess = loJwe.EncryptBd(loJpgBytes,loSbJwe)
if (llSuccess <> .T.) then
    ? loJwe.LastErrorText
    release loJpgBytes
    release loJwe
    release loJweProtHdr
    release loSbJwe
    return
endif

// Show the JWE:
? loSbJwe.GetAsString()
? "size of JWE: " + str(loSbJwe.Length)

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

loJwe2 = createobject("CkJwe")
llSuccess = loJwe2.LoadJweSb(loSbJwe)
if (llSuccess <> .T.) then
    ? loJwe2.LastErrorText
    release loJpgBytes
    release loJwe
    release loJweProtHdr
    release loSbJwe
    release loJwe2
    return
endif

// Set the AES wrap key.
loJwe2.SetWrappingKey(0,lcAesWrappingKey,"base64url")

// Decrypt.
loJpgOriginal = createobject("CkBinData")
llSuccess = loJwe2.DecryptBd(0,loJpgOriginal)
if (llSuccess <> .T.) then
    ? loJwe2.LastErrorText
    release loJpgBytes
    release loJwe
    release loJweProtHdr
    release loSbJwe
    release loJwe2
    release loJpgOriginal
    return
endif

? "Decrypted JPG size = " + str(loJpgOriginal.NumBytes)

// Save the decrypted JPG to a file.
llSuccess = loJpgOriginal.WriteFile("qa_output/jwe_decrypted_starfish.jpg")

? "success = " + str(llSuccess)

// 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


release loJpgBytes
release loJwe
release loJweProtHdr
release loSbJwe
release loJwe2
release loJpgOriginal