(Swift 3,4,5...) Ed25519ph Sign and Verify

Demonstrates how to create an Ed25519ph signature, and then to verify it.

Note: This example requires Chilkat v9.5.0.91 or greater.

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func chilkatTest() {
    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Use the following test vector from https://www.rfc-editor.org/rfc/rfc8032#page-30

    //    -----TEST abc
    // 
    //    ALGORITHM:
    //    Ed25519ph
    // 
    //    SECRET KEY:
    //    833fe62409237b9d62ec77587520911e
    //    9a759cec1d19755b7da901b96dca3d42
    // 
    //    PUBLIC KEY:
    //    ec172b93ad5e563bf4932c70e1245034
    //    c35467ef2efd4d64ebf819683467e2bf
    // 
    //    MESSAGE (length 3 bytes):
    //    616263
    // 
    //    SIGNATURE:
    //    98a70222f0b8121aa9d30f813d683f80
    //    9e462b469c7ff87639499bb94e6dae41
    //    31f85042463c2a355a2003d062adf5aa
    //    a10b8c61e636062aaad11c2a26083406

    var privKeyHex: String? = "833fe62409237b9d62ec77587520911e9a759cec1d19755b7da901b96dca3d42"
    var pubKeyHex: String? = "ec172b93ad5e563bf4932c70e1245034c35467ef2efd4d64ebf819683467e2bf"

    let privKey = CkoPrivateKey()!
    var success: Bool = privKey.loadEd25519(privKeyHex, pubKey: pubKeyHex)
    if success == false {
        print("\(privKey.lastErrorText!)")
        return
    }

    // The data to be signed...
    let bd = CkoBinData()!
    bd.appendEncoded("616263", encoding: "hex")

    let eddsa = CkoEdDSA()!
    // Indicate we want the Ed25519ph instance.
    eddsa.algorithm = "Ed25519ph"

    var hexSig: String? = eddsa.signBdENC(bd, encoding: "hexlower", privkey: privKey)

    print("signature = \(hexSig!)")

    // The expected output is: 98a70222f0b8121aa9d30f813d683f80....

    // Verify the signature..
    let pubKey = CkoPublicKey()!
    success = pubKey.loadEd25519(pubKeyHex)
    if success == false {
        print("\(pubKey.lastErrorText!)")
        return
    }

    var bVerified: Bool = eddsa.verifyBdENC(bd, encodedSig: hexSig, enocding: "hexlower", pubkey: pubKey)
    if bVerified == false {
        print("\(eddsa.lastErrorText!)")
        print("Failed to verify the signature.")
        return
    }

    print("The Ed25519ph signature is verified!")

}