End to End Encryption

E2EE.java

import java.security.*;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

import javax.crypto.Cipher;

public class E2EE {
    private KeyPair keyPair;
    private String publicKey;
    private String privateKey;

    public E2EE() throws NoSuchAlgorithmException {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
        keyGen.initialize(2048);
        keyPair = keyGen.generateKeyPair();
        publicKey = Base64.getEncoder().encodeToString(keyPair.getPublic().getEncoded());
        privateKey = Base64.getEncoder().encodeToString(keyPair.getPrivate().getEncoded());
    }

    public String getPublicKey() {
        return publicKey;
    }

    public String getPrivateKey() {
        return privateKey;
    }

    public byte[] encrypt(String publicKey, byte[] message) throws Exception {
        // Decode the public key from base64
        byte[] decodedPublicKey = Base64.getDecoder().decode(publicKey);
        PublicKey key = KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decodedPublicKey));

        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(message);
    }

    public byte[] decrypt(byte[] message) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, keyPair.getPrivate());
        return cipher.doFinal(message);
    }
}