@RequiresApi(Build.VERSION_CODES.M)
fun generateKeyPair(): KeyPair {
    val keyGen = KeyPairGenerator.getInstance(KeyProperties.KEY_ALGORITHM_RSA, "AndroidKeyStore")
    keyGen.initialize(KeyGenParameterSpec.Builder("alias1", KeyProperties.PURPOSE_SIGN)
            .setSignaturePaddings(KeyProperties.SIGNATURE_PADDING_RSA_PKCS1)
            .setDigests(KeyProperties.DIGEST_SHA512)
            .build())

        return keyGen.generateKeyPair()
}