yakivmospan

val message = "Very large message, bigger then 250 symblos..."

// Simple Shared Preferences wrapper, will be used to save wrapped key
val storage = Storage(context)

// Creates Android Key Store and provides manage functions
val keyStoreWrapper = KeyStoreWrapper(context)

// Running M and later, use one symmetric key
if (SystemServices.hasMarshmallow()) {

yakivmospan

companion object {
    var TRANSFORMATION_SYMMETRIC = "AES/CBC/PKCS7Padding"
}

yakivmospan

fun unWrapKey(wrappedKeyData: String, algorithm: String, wrappedKeyType: Int, keyToUnWrapWith: Key?): Key {
    val encryptedKeyData = Base64.decode(wrappedKeyData, Base64.DEFAULT)
    cipher.init(Cipher.UNWRAP_MODE, keyToUnWrapWith)
    return cipher.unwrap(encryptedKeyData, algorithm, wrappedKeyType)
}

yakivmospan

fun wrapKey(keyToBeWrapped: Key, keyToWrapWith: Key?): String {
    cipher.init(Cipher.WRAP_MODE, keyToWrapWith)
    val decodedData = cipher.wrap(keyToBeWrapped)
    return Base64.encodeToString(decodedData, Base64.DEFAULT)
}

yakivmospan

@TargetApi(23)
fun createAndroidKeyStoreSymmetricKey(alias: String): SecretKey {
    val keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore")
    val builder = KeyGenParameterSpec.Builder(alias, KeyProperties.PURPOSE_ENCRYPT or KeyProperties.PURPOSE_DECRYPT)
            .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
            .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
    keyGenerator.init(builder.build())
    return keyGenerator.generateKey()
}

yakivmospan

fun generateDefaultSymmetricKey(): SecretKey {
    val keyGenerator = KeyGenerator.getInstance("AES", "BC")
    return keyGenerator.generateKey()
}

yakivmospan

var message = "Hello Word"

// Creates Android Key Store and provides manage functions
private val keyStoreWrapper = KeyStoreWrapper(context)

// Create and Save asymmetric key
keyStoreWrapper.createAndroidKeyStoreAsymmetricKey("MASTER_KEY")

// Get key from keyStore
var masterKey = keyStoreWrapper.getAndroidKeyStoreAsymmetricKeyPair("MASTER_KEY")

yakivmospan

.setCertificateNotBefore(startDate) // By default, this date is Jan 1 1970.
.setCertificateNotAfter(endDate) // By default, this date is Jan 1 2048.
.setCertificateSerialNumber(number) // By default, the serial number is 1.
.setCertificateSubject(x500Principal) // By default, the subject is CN=fake.

yakivmospan

fun decrypt(data: String, key: Key?): String {
    cipher.init(Cipher.DECRYPT_MODE, key)
    val encryptedData = Base64.decode(data, Base64.DEFAULT)
    val decodedData = cipher.doFinal(encryptedData)
    return String(decodedData)
}

yakivmospan

fun encrypt(data: String, key: Key?): String {
    cipher.init(Cipher.ENCRYPT_MODE, key)
    val bytes = cipher.doFinal(data.toByteArray())
    return Base64.encodeToString(bytes, Base64.DEFAULT)
}