(Swift 2) Streaming Encryption

Encrypt and decrypt using a stream.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

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

    let crypt = CkoCrypt2()

    // Setup encryption using the chacha20 algorithm...
    crypt.CryptAlgorithm = "chacha20"
    crypt.KeyLength = 256
    crypt.EncodingMode = "hex"
    var ivHex: String? = "000000000000000000000002"
    crypt.SetEncodedIV(ivHex, encoding: "hex")
    crypt.InitialCount = 42
    var keyHex: String? = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0"
    crypt.SetEncodedKey(keyHex, encoding: "hex")

    var plainText: String? = "The quick brown fox jumped over the lazy dog.\r\n"

    let stream = CkoStream()

    // We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
    let eStrings = CkoStringArray()

    // Start a background task that will encrypt a stream.
    var task: CkoTask? = crypt.EncryptStreamAsync(stream)
    var success: Bool = task!.Run()

    // Write plainText to the stream, and read chacha20 encrypted text..
    var cipherText: String?
    var i: Int
    for i = 1; i <= 10; i++ {
        // Note: An encryption algorithm's block size will cause buffering,
        // and therefore not every loop iteration will produce output.
        success = stream.WriteString(plainText)
        if stream.DataAvailable == true {
            cipherText = stream.ReadBytesENC("hex")
            print("\(cipherText!)")
            success = eStrings.Append(cipherText)
        }

    }

    // Tell the background task that the stream has ended.
    success = stream.WriteClose()

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    while (task!.Finished != true) {
        task!.SleepMs(20)
    }

    // Get any remaining data available from the stream.
    if stream.DataAvailable == true {
        cipherText = stream.ReadBytesENC("hex")
        print("\(cipherText!)")
        success = eStrings.Append(cipherText)
    }

    if task!.TaskSuccess != true {
        print("async encryption failed:")
        print("\(task!.ResultErrorText)")
        success = false
    }

    task = nil

    print("-- encrypt finished --")

    // Now decrypt to return the original.

    // Reset the stream object so it can be used again.
    stream.Reset()

    // Start a background task that will decrypt a stream.
    task = crypt.DecryptStreamAsync(stream)
    success = task!.Run()

    var n: Int = eStrings.Count.intValue
    for i = 0; i <= n - 1; i++ {
        success = stream.WriteBytesENC(eStrings.GetString(i), encoding: "hex")
        if stream.DataAvailable == true {
            plainText = stream.ReadString()
            print("\(plainText!)")
        }

    }

    // Tell the background task that the stream has ended.
    success = stream.WriteClose()

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    while (task!.Finished != true) {
        task!.SleepMs(20)
    }

    // Get any remaining data available from the stream.
    if stream.DataAvailable == true {
        plainText = stream.ReadString()
        print("\(plainText!)")
    }

    if task!.TaskSuccess != true {
        print("async decryption failed:")
        print("\(task!.ResultErrorText)")
        success = false
    }

    task = nil

    print("-- decrypt finished --")

}