Aes256GcmTest

Aes256GcmTest.java

package org.eclipse.milo.opcua.stack;

import java.security.SecureRandom;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.eclipse.milo.opcua.stack.core.util.CryptoRestrictions;
import org.testng.annotations.Test;

import static org.testng.Assert.assertTrue;

public class Aes256GcmTest {

    static {
        // Needed for 256-bit key length.
        // Could install unlimited strength crypto policies instead.
        CryptoRestrictions.remove();
    }

    private static final String TRANSFORMATION = "AES/GCM/NoPadding";

    private static final byte[] KEY = new byte[32];
    private static final byte[] NONCE = new byte[12];

    @Test
    public void testAesGcm() throws Exception {
        SecureRandom secureRandom = SecureRandom.getInstanceStrong();
        secureRandom.nextBytes(KEY);
        secureRandom.nextBytes(NONCE);

        byte[] plainText = new byte[]{1, 2, 3, 4};

        byte[] cipherText = encrypt(plainText);

        System.out.println("plainText: " + Arrays.toString(plainText));
        System.out.println("cipherText: " + Arrays.toString(cipherText));

        byte[] plainTextPrime = decrypt(cipherText);

        System.out.println("plainTextPrime: " + Arrays.toString(plainTextPrime));

        assertTrue(Arrays.equals(plainText, plainTextPrime));
    }

    private byte[] encrypt(byte[] plainText) throws Exception {
        SecretKeySpec keySpec = new SecretKeySpec(KEY, "AES");
        GCMParameterSpec parameterSpec = new GCMParameterSpec(128, NONCE);

        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, keySpec, parameterSpec);

        return cipher.doFinal(plainText);
    }

    private byte[] decrypt(byte[] cipherText) throws Exception {
        SecretKeySpec keySpec = new SecretKeySpec(KEY, "AES");
        GCMParameterSpec parameterSpec = new GCMParameterSpec(128, NONCE);

        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, keySpec, parameterSpec);

        return cipher.doFinal(cipherText);
    }

}