Java11: ChaCha20 Encryption

Photo by Ham Kris on Unsplash

Java 11 comes with ChaCha20 steam cipher. Let’s see how to use it.

package com.nuwan.java11;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.ChaCha20ParameterSpec;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

public class ChaCha20Encryption {
    public static void main(String[] args) throws Exception {
        String input = "Java & ChaCha20 encryption example.";
        ChaCha20 chaCha20 = new ChaCha20();
        SecretKey key = getKey();
        byte[] nonce =getNonce();
        int counter = 1;

        ChaCha20 cipher = new ChaCha20();

        byte[] cText=cipher.encrypt(input.getBytes(),key,nonce,counter);
        System.out.println(new String(cText));
        byte[] ptext=cipher.decrypt(cText,key,nonce,counter);
        System.out.println(new String( ptext));
    }

    private static byte[] getNonce() {
        byte[] newNonce = new byte[12];
        new SecureRandom().nextBytes(newNonce);
        return newNonce;
    }

    private static SecretKey getKey() throws NoSuchAlgorithmException {
        KeyGenerator keyGen=KeyGenerator.getInstance("ChaCha20");
        keyGen.init(256, SecureRandom.getInstanceStrong());
        return keyGen.generateKey();
    }


}

class ChaCha20{
    public byte[] encrypt(byte[] pText, SecretKey key, byte[] nonce, int counter) throws Exception {
        Cipher cipher = Cipher.getInstance("ChaCha20");
        ChaCha20ParameterSpec param=new ChaCha20ParameterSpec(nonce, counter);
        cipher.init(Cipher.ENCRYPT_MODE,key,param);
        byte[] encryptedText=cipher.doFinal(pText);
        return encryptedText;
    }
    public byte[] decrypt(byte[] cText, SecretKey key, byte[] nonce, int counter ) throws Exception {

        Cipher cipher=Cipher.getInstance("ChaCha20");
        ChaCha20ParameterSpec param=new ChaCha20ParameterSpec(nonce, counter);
        cipher.init(Cipher.DECRYPT_MODE,key,param);
        byte[] decryptedText = cipher.doFinal(cText);
        return  decryptedText;
    }
}

Ref: https://mkyong.com/java/java-11-chacha20-stream-cipher-examples/

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