com.vexsoftware.votifier.crypto.RSAIO.java Source code

Introduction

Here is the source code for com.vexsoftware.votifier.crypto.RSAIO.java

Source

/*
 * Copyright (C) 2011 Vex Software LLC
 * This file is part of Votifier.
 * 
 * Votifier is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * Votifier is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with Votifier.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.vexsoftware.votifier.crypto;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.FileOutputStream;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.xml.bind.DatatypeConverter;

/**
 * Static utility methods for saving and loading RSA key pairs.
 */
public class RSAIO {

    /**
     * Saves the key pair to the disk.
     * 
     * @param directory
     *            The directory to save to
     * @param keyPair
     *            The key pair to save
     * @throws Exception
     *             If an error occurs
     */
    public static void save(File directory, KeyPair keyPair) throws Exception {
        PrivateKey privateKey = keyPair.getPrivate();
        PublicKey publicKey = keyPair.getPublic();

        // Store the public key.
        X509EncodedKeySpec publicSpec = new X509EncodedKeySpec(publicKey.getEncoded());
        FileOutputStream out = new FileOutputStream(directory + "/public.key");
        out.write(DatatypeConverter.printBase64Binary(publicSpec.getEncoded()).getBytes());
        out.close();

        // Store the private key.
        PKCS8EncodedKeySpec privateSpec = new PKCS8EncodedKeySpec(privateKey.getEncoded());
        out = new FileOutputStream(directory + "/private.key");
        out.write(DatatypeConverter.printBase64Binary(privateSpec.getEncoded()).getBytes());
        out.close();
    }

    /**
     * Loads an RSA key pair from a directory. The directory must have the files
     * "public.key" and "private.key".
     * 
     * @param directory
     *            The directory to load from
     * @return The key pair
     * @throws Exception
     *             If an error occurs
     */
    public static KeyPair load(File directory) throws Exception {
        // Read the public key file.
        File publicKeyFile = new File(directory + "/public.key");
        byte[] encodedPublicKey = FileUtils.readFileToByteArray(publicKeyFile);
        encodedPublicKey = DatatypeConverter.parseBase64Binary(new String(encodedPublicKey));

        // Read the private key file.
        File privateKeyFile = new File(directory + "/private.key");
        byte[] encodedPrivateKey = FileUtils.readFileToByteArray(privateKeyFile);
        encodedPrivateKey = DatatypeConverter.parseBase64Binary(new String(encodedPrivateKey));

        // Instantiate and return the key pair.
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(encodedPublicKey);
        PublicKey publicKey = keyFactory.generatePublic(publicKeySpec);
        PKCS8EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(encodedPrivateKey);
        PrivateKey privateKey = keyFactory.generatePrivate(privateKeySpec);
        return new KeyPair(publicKey, privateKey);
    }

}