Public key RSA cipher sample

CipherMaker.kt

package com.example.rsatest

import android.security.keystore.KeyProperties
import android.util.Base64
import java.security.Key
import java.security.KeyFactory
import java.security.spec.X509EncodedKeySpec
import javax.crypto.Cipher

private const val ALGORITHM = KeyProperties.KEY_ALGORITHM_RSA

class CipherMaker {

    private val publicKey =
        "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvXmMURuCLR3Vx/slaQaQB/hXDxnhrKK+RjZpUtHBsNuU1PRsz3WlWuGhUSyd+jaxTKI6R+ftJduNfFriND9DP8+Zc+Fo5S+r7mD8lfjgprUo4hDHUtlGbMo8XxwW4ktJPuFRASeiW9lWyPIo0iXu1aJ7wQ9/6Z6KDtAowtpMi0JSqisGP/SzRDs7O+4oxhrvdcZD1XRm6IOv47CBLjX26c7juu+ZYc4XrpBSLUcF753m94xzHH1x9EigJNqHJWNuRE1ltJzbS+DWixnJyTomf6+mLZ09O5js5FUFkaAWKoe0D9j+eGNoqmePkh/lFpWt1ZF9Y4OZh3HGxM1o2oxXJwIDAQAB"

    private val rsaKey by lazy { createKey() }
    private val cipher by lazy { Cipher.getInstance(ALGORITHM) }

    private fun createKey(): Key {
        val publicKeyHardCoded = Base64.decode(publicKey, Base64.NO_WRAP)


        val key = X509EncodedKeySpec(publicKeyHardCoded) //PKCS8EncodedKeySpec(publicKeyHardCoded)
        return KeyFactory.getInstance(ALGORITHM)
            .generatePublic(key)
    }

    fun encript(textToCipher: String): ByteArray {
        cipher.init(Cipher.ENCRYPT_MODE, rsaKey)

        return cipher.doFinal(textToCipher.toByteArray())
    }

    fun decript(byteArray: ByteArray): String {
        cipher.init(Cipher.DECRYPT_MODE, rsaKey)

        val doFinal = cipher.doFinal(byteArray)

        return String(doFinal)
    }
}

CipherMakerTest.kt

package com.example.rsatest

import org.junit.Assert.assertNotEquals
import org.junit.Test

class CipherMakerTest {

    val cipherMaker = CipherMaker()

    @Test
    fun cipherShouldNotBeEmpty() {
        val encripted = cipherMaker.encript("Text")

        assertNotEquals(0, encripted.size)
    }

    @Test
    fun cipherShouldNotBeRevertedToSameValueDueToOnlyRSAPublicKey() {
        val textToCipher = "Text"

        val encripted = cipherMaker.encript(textToCipher)
        val decripted = cipherMaker.decript(encripted)

        assertNotEquals(textToCipher, decripted)
    }
}