Xbase++

JWE with Binary Data

See more JSON Web Encryption (JWE) Examples

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.

Xbase++

LOCAL nSuccess
LOCAL oJpgBytes
LOCAL oJwe
LOCAL oJweProtHdr
LOCAL cAesWrappingKey
LOCAL oSbJwe
LOCAL oJwe2
LOCAL oJpgOriginal

nSuccess := 0

//  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.
oJpgBytes := CreateObject("Chilkat.BinData")
nSuccess := oJpgBytes:LoadFile("qa_data/jpg/starfish.jpg")
//  Make sure your app checks the success/failure of the call to LoadFile..
? "Original JPG size = " + Str(oJpgBytes:NumBytes)

oJwe := CreateObject("Chilkat.Jwe")

oJweProtHdr := CreateObject("Chilkat.JsonObject")
oJweProtHdr:AppendString("alg", "A128KW")
oJweProtHdr:AppendString("enc", "A128CBC-HS256")
oJwe:SetProtectedHeader(oJweProtHdr)

cAesWrappingKey := "GawgguFyGrWKav7AX4VKUg"
oJwe:SetWrappingKey(0, cAesWrappingKey, "base64url")

//  Encrypt and return the JWE in sbJwe:
oSbJwe := CreateObject("Chilkat.StringBuilder")
nSuccess := oJwe:EncryptBd(oJpgBytes, oSbJwe)
IF (nSuccess != 1)
    ? oJwe:LastErrorText
    oJpgBytes:destroy()
    oJwe:destroy()
    oJweProtHdr:destroy()
    oSbJwe:destroy()
    RETURN
ENDIF

//  Show the JWE:
? oSbJwe:GetAsString()
? "size of JWE: " + Str(oSbJwe:Length)

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

oJwe2 := CreateObject("Chilkat.Jwe")
nSuccess := oJwe2:LoadJweSb(oSbJwe)
IF (nSuccess != 1)
    ? oJwe2:LastErrorText
    oJpgBytes:destroy()
    oJwe:destroy()
    oJweProtHdr:destroy()
    oSbJwe:destroy()
    oJwe2:destroy()
    RETURN
ENDIF

//  Set the AES wrap key.
oJwe2:SetWrappingKey(0, cAesWrappingKey, "base64url")

//  Decrypt.
oJpgOriginal := CreateObject("Chilkat.BinData")
nSuccess := oJwe2:DecryptBd(0, oJpgOriginal)
IF (nSuccess != 1)
    ? oJwe2:LastErrorText
    oJpgBytes:destroy()
    oJwe:destroy()
    oJweProtHdr:destroy()
    oSbJwe:destroy()
    oJwe2:destroy()
    oJpgOriginal:destroy()
    RETURN
ENDIF

? "Decrypted JPG size = " + Str(oJpgOriginal:NumBytes)

//  Save the decrypted JPG to a file.
nSuccess := oJpgOriginal:WriteFile("qa_output/jwe_decrypted_starfish.jpg")

? "success = " + Str(nSuccess)

//  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

oJpgBytes:destroy()
oJwe:destroy()
oJweProtHdr:destroy()
oSbJwe:destroy()
oJwe2:destroy()
oJpgOriginal:destroy()