package RSATest;

import javacard.security.*;
import javacardx.crypto.*;
import javacard.framework.*;

public class RSATest extends Applet
{
    RSAPrivateCrtKey priv;
    RSAPublicKey pub;
    KeyPair kp;
    RandomData rng;

    Cipher rsa;

    byte[] inBuffer = new byte[256];
    byte[] outBuffer = new byte[256];

    public RSATest() {

        // Generate our CSP's
        rng = RandomData.getInstance(RandomData.ALG_SECURE_RANDOM);
        rsa = Cipher.getInstance(Cipher.ALG_RSA_PKCS1, false);

        // Generate the KeyPair
        priv = (RSAPrivateCrtKey)KeyBuilder.buildKey(KeyBuilder.TYPE_RSA_CRT_PRIVATE, KeyBuilder.LENGTH_RSA_2048, false);
        pub = (RSAPublicKey)KeyBuilder.buildKey(KeyBuilder.TYPE_RSA_PUBLIC, KeyBuilder.LENGTH_RSA_2048, false);
        kp = new KeyPair(pub, priv);
        kp.genKeyPair();

    }

    public static void install(byte[] bArray, short bOffset, byte bLength)
    {
        new RSATest().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
    }

    public void process(APDU apdu)
    {
        if (selectingApplet()) return;

        byte[] buf = apdu.getBuffer();

        switch (buf[ISO7816.OFFSET_INS])
        {

        case (byte)0x01:

            // Clear the buffers
            Util.arrayFillNonAtomic(inBuffer, (short)0, (short)256, (byte)0);
            Util.arrayFillNonAtomic(outBuffer, (short)0, (short)256, (byte)0);

            // Generate some random data
            rng.generateData(inBuffer, (short)0, (short)128);

            // RSA Encrypt from inBuffer to outBuffer (length 128)
            rsa.init(pub, Cipher.MODE_ENCRYPT);
            rsa.doFinal(inBuffer, (short)0, (short)128, outBuffer, (short)0);
            break;

        case (byte)0x02:

            // RSA Decrypt from outBuffer to inBuffer (length 256)
            rsa.init(priv, Cipher.MODE_DECRYPT);
            rsa.doFinal(outBuffer, (short)0, (short)256, inBuffer, (short)0);
            break;

        default:
            ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
        }
    }

}