(Swift 3,4,5...) JWE using "dir" Direct use of Shared Symmetric Key

Demonstrates how to create a JWE using the "dir" alg -- which is to directly use a shared symmetric key.

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

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func chilkatTest() {
    // 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.

    var success: Bool
    var plaintext: String? = "Live long and prosper."

    let jwe = CkoJwe()!

    // First build the JWE Protected Header..
    let jweProtHdr = CkoJsonObject()!
    jweProtHdr.append("alg", value: "dir")
    jweProtHdr.append("enc", value: "A128GCM")

    // Don't forget to actually provide the protected header to the JWE object:
    jwe.setProtectedHeader(jweProtHdr)

    // The JWE is to use 128-bit AES GCM encryption as specified by the "enc" parameter.
    // Given that the "alg" = "dir", we are to directly specify the AES GCM key.
    // (It is assumed that the decrypting side also has knowledge of the direct key to be used..)

    // Our key will be these 16 hex bytes: 000102030405060708090A0B0C0D0E0F

    // The SetWrappingKey method is also used for "dir" direct keys.
    // However, if there are multiple recipients, they must all share the same CEK (Content Encryption Key),
    // which is specified by calling SetWrappingKey with an index of 0.

    var recipientIndex: Int = 0
    jwe.setWrappingKey(recipientIndex, encodedKey: "000102030405060708090A0B0C0D0E0F", encoding: "hex")

    // Encrypt and return the JWE:
    var strJwe: String? = jwe.encrypt(plaintext, charset: "utf-8")
    if jwe.lastMethodSuccess != true {
        print("\(jwe.lastErrorText!)")
        return
    }

    // Show the JWE we just created:
    print("\(strJwe!)")

    // Decrypt the JWE.
    let jwe2 = CkoJwe()!
    success = jwe2.load(strJwe)
    if success != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    jwe2.setWrappingKey(0, encodedKey: "000102030405060708090A0B0C0D0E0F", encoding: "hex")

    // Decrypt.
    var originalPlaintext: String? = jwe2.decrypt(0, charset: "utf-8")
    if jwe2.lastMethodSuccess != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    print("original text: ")
    print("\(originalPlaintext!)")

    // Sample output:
    // eyJhbGciOiJkaXIiLCJlbmMiOiJBMTI4R0NNIn0..20HX5Huc7f1nQC4pBUtiCQ.axFZIxtZy5j0ifJQUzGXLKIpsBuxJA.eBrOC-NrsreN6JeGuOPk1g
    // original text: 
    // Live long and prosper.

}