PBKDF2 Implementation

PasswordEncryptionService.java

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.util.Arrays;

import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;

public class PasswordEncryptionService {
    
    public boolean authenticate(String attemptedPassword, byte[] encryptedPassword, byte[] salt)
        throws NoSuchAlgorithmException, InvalidKeySpecException {
            byte[] encryptedAttemptedPassword = getEncryptedPassword(attemptedPassword, salt);

            return Arrays.equals(encryptedPassword, encryptedAttemptedPassword);
    }

    public byte[] getEncryptedPassword(String password, byte[] salt)
     throws NoSuchAlgorithmException, InvalidKeySpecException {
        String algorithm = "PBKDF2WithHmacSHA1";
        int derivedKeyLength = 160;
        int iterations = 20000;

        KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, iterations, derivedKeyLength);

        SecretKeyFactory f = SecretKeyFactory.getInstance(algorithm);

        return f.generateSecret(spec).getEncoded();
    }

    public byte[] generateSalt() throws NoSuchAlgorithmException {
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG");

        byte[] salt = new byte[8];
        random.nextBytes(salt);

        return salt;
    }
}