Aes Util fo rencrypt to aes 256

Aes256.kt

object Aes256 {

    private fun cipher(operationMode: Int, secretKey: String = BuildConfig.KEY_ENCRYPT): Cipher {
        if (secretKey.length != 32) throw RuntimeException("SecretKey length is not 32 chars")
        val c = Cipher.getInstance("AES/CBC/PKCS5Padding")
        val sk = SecretKeySpec(secretKey.toByteArray(Charsets.UTF_8), "AES")
        val iv = IvParameterSpec(secretKey.substring(0, 16).toByteArray(Charsets.UTF_8))
        c.init(operationMode, sk, iv)
        return c
    }

    fun encrypt(str: String, secretKey: String = BuildConfig.KEY_ENCRYPT): String {
        val encrypted =
            cipher(Cipher.ENCRYPT_MODE, secretKey).doFinal(str.toByteArray(Charsets.UTF_8))
        return String(Base64.encode(encrypted, Base64.DEFAULT))
    }

    fun decrypt(str: String, secretKey: String = BuildConfig.KEY_ENCRYPT): String {
        val byteStr = Base64.decode(str.toByteArray(Charsets.UTF_8), Base64.DEFAULT)
        return String(cipher(Cipher.DECRYPT_MODE, secretKey).doFinal(byteStr))
    }

}