Create Facebook Conceal Crypto With User Supplied Password (Kotlin)

class PasswordGeneratedKeyChain(private val mConfig: CryptoConfig) : KeyChain {    private val mDerivation: PasswordBasedKeyDerivation    private var mKey: ByteArray? = null    init {        // mDerivation = PasswordBasedKeyDerivation(AndroidConceal.get().nativeLibrary)        mDerivation = AndroidConceal.get().createPasswordBasedKeyDerivation()        mDerivation.keyLengthInBytes = mConfig.keyLength    }    /// implementing Key Chain    override fun getCipherKey(): ByteArray {        if (mKey == null) throw IllegalStateException("You need to call generate() first")        return mKey as ByteArray    }    // key for mac    // if you need mac you need a second derivation object    override fun getMacKey(): ByteArray {        throw UnsupportedOperationException("implemented only for encryption, not mac")    }    // this is just a glorified "get me a new nonce"    override fun getNewIV(): ByteArray {        val result = ByteArray(mConfig.ivLength)        AndroidConceal.get().secureRandom.nextBytes(result)        return result    }    override fun destroyKeys() {        Arrays.fill(mKey, 0.toByte())        mKey = null    }    // used only for encrypting, you will need to store it in the same place you're writing the encrypted content    // used only for reading, it should read the salt from the same place the encrypted content is    var salt: ByteArray        get() = mDerivation.salt        set(salt) {            mDerivation.salt = salt        }    fun setPassword(pwd: String) {        mDerivation.password = pwd    }    fun generate() {        mKey = mDerivation.generate()    }}

val pgkc = PasswordGeneratedKeyChain(CryptoConfig.KEY_256)pgkc.setPassword(password)pgkc.salt = salt.toByteArray()pgkc.generate()val crypto = AndroidConceal.get().createDefaultCrypto(pgkc)