package it.ipzs.cieidsdk.nfc.algorithms


import it.ipzs.cieidsdk.nfc.extensions.toHex
import javax.crypto.Cipher
import java.math.BigInteger
import java.security.KeyFactory
import java.security.interfaces.RSAPrivateKey
import java.security.spec.RSAPrivateKeySpec

internal class RSA @Throws(Exception::class)
constructor(mod: ByteArray, exp: ByteArray) {

    private var key: RSAPrivateKey? = null
    private var cipher: Cipher? = null

    init {
        createPrivateKey(mod, exp)
    }


    @Throws(Exception::class)
    fun createPrivateKey(modulo: ByteArray, esponente: ByteArray) {

        val modulus = BigInteger(modulo.toHex(), 16)
        val privateExp = BigInteger(esponente.toHex(), 16)

        val keyFactory: KeyFactory? = KeyFactory.getInstance("RSA")
        val pubKeySpec = RSAPrivateKeySpec(modulus, privateExp)

        cipher = Cipher.getInstance("RSA/ECB/NoPadding")
        this.key = keyFactory!!.generatePrivate(pubKeySpec) as RSAPrivateKey


    }

    @Throws(Exception::class)
    fun encrypt(data: ByteArray): ByteArray {

        cipher!!.init(Cipher.DECRYPT_MODE, key)
        return cipher!!.doFinal(data)
    }
}