(Swift 2) AES XTS Mode

Demonstrates the AES-XTS mode of operation.

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.

    var success: Bool

    // Here we have a sample from CAVS validatition data:

    // COUNT = 301
    // DataUnitLen = 200
    // Key = 
    // 394c97881abd989d29c703e48a72b397
    // a7acf51b59649eeea9b33274d8541df4
    // i = 4b15c684a152d485fe9937d39b168c29
    // PT = 2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0
    // CT = f3473802e38a3ffef4d4fb8e6aa266ebde553a64528a06463e

    // Note: The above sample requires an AES-XTS implementation that fully supports ciphertext-stealing
    // because the data to be encrypted is not an even multiple of the AES block size (i.e. not a multiple of 16 bytes).
    // Chilkat fully supports AES-XTS with ciphertext stealing.
    // (i.e. Chilkat implements XEX-based tweaked-codebook mode with ciphertext stealing (XTS))

    var key: String? = "394c97881abd989d29c703e48a72b397"
    var tweakKey: String? = "a7acf51b59649eeea9b33274d8541df4"
    var dataUnit: String? = "4b15c684a152d485fe9937d39b168c29"

    let bd = CkoBinData()
    bd.AppendEncoded("2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0", encoding: "hex")

    let crypt = CkoCrypt2()

    crypt.CryptAlgorithm = "aes"
    crypt.CipherMode = "xts"
    crypt.KeyLength = 128

    crypt.SetEncodedKey(key, encoding: "hex")
    crypt.XtsSetEncodedTweakKey(tweakKey, encoding: "hex")
    crypt.XtsSetEncodedTweakValue(dataUnit, encoding: "hex")

    // In-place encrypt the contents of bd.
    success = crypt.EncryptBd(bd)

    print("CT = \(bd.GetEncoded("hexlower"))")

    // Decrypt to revert back to the unencrypted content:
    success = crypt.DecryptBd(bd)

    print("PT = \(bd.GetEncoded("hexlower"))")

    // Output:
    // CT = f3473802e38a3ffef4d4fb8e6aa266ebde553a64528a06463e
    // PT = 2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0

}