(PureBasic) 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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IncludeFile "CkBinData.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJwe.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    ; 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.

    success.i

    ; Load a JPG file that will be the JWE payload.
    jpgBytes.i = CkBinData::ckCreate()
    If jpgBytes.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkBinData::ckLoadFile(jpgBytes,"qa_data/jpg/starfish.jpg")
    ; Make sure your app checks the success/failure of the call to LoadFile..
    Debug "Original JPG size = " + Str(CkBinData::ckNumBytes(jpgBytes))

    jwe.i = CkJwe::ckCreate()
    If jwe.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    jweProtHdr.i = CkJsonObject::ckCreate()
    If jweProtHdr.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckAppendString(jweProtHdr,"alg","A128KW")
    CkJsonObject::ckAppendString(jweProtHdr,"enc","A128CBC-HS256")
    CkJwe::ckSetProtectedHeader(jwe,jweProtHdr)

    aesWrappingKey.s = "GawgguFyGrWKav7AX4VKUg"
    CkJwe::ckSetWrappingKey(jwe,0,aesWrappingKey,"base64url")

    ; Encrypt and return the JWE in sbJwe:
    sbJwe.i = CkStringBuilder::ckCreate()
    If sbJwe.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJwe::ckEncryptBd(jwe,jpgBytes,sbJwe)
    If success <> 1
        Debug CkJwe::ckLastErrorText(jwe)
        CkBinData::ckDispose(jpgBytes)
        CkJwe::ckDispose(jwe)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwe)
        ProcedureReturn
    EndIf

    ; Show the JWE:
    Debug CkStringBuilder::ckGetAsString(sbJwe)
    Debug "size of JWE: " + Str(CkStringBuilder::ckLength(sbJwe))

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

    jwe2.i = CkJwe::ckCreate()
    If jwe2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJwe::ckLoadJweSb(jwe2,sbJwe)
    If success <> 1
        Debug CkJwe::ckLastErrorText(jwe2)
        CkBinData::ckDispose(jpgBytes)
        CkJwe::ckDispose(jwe)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwe)
        CkJwe::ckDispose(jwe2)
        ProcedureReturn
    EndIf

    ; Set the AES wrap key.
    CkJwe::ckSetWrappingKey(jwe2,0,aesWrappingKey,"base64url")

    ; Decrypt.
    jpgOriginal.i = CkBinData::ckCreate()
    If jpgOriginal.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJwe::ckDecryptBd(jwe2,0,jpgOriginal)
    If success <> 1
        Debug CkJwe::ckLastErrorText(jwe2)
        CkBinData::ckDispose(jpgBytes)
        CkJwe::ckDispose(jwe)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwe)
        CkJwe::ckDispose(jwe2)
        CkBinData::ckDispose(jpgOriginal)
        ProcedureReturn
    EndIf

    Debug "Decrypted JPG size = " + Str(CkBinData::ckNumBytes(jpgOriginal))

    ; Save the decrypted JPG to a file.
    success = CkBinData::ckWriteFile(jpgOriginal,"qa_output/jwe_decrypted_starfish.jpg")

    Debug "success = " + Str(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


    CkBinData::ckDispose(jpgBytes)
    CkJwe::ckDispose(jwe)
    CkJsonObject::ckDispose(jweProtHdr)
    CkStringBuilder::ckDispose(sbJwe)
    CkJwe::ckDispose(jwe2)
    CkBinData::ckDispose(jpgOriginal)


    ProcedureReturn
EndProcedure