/* ==================================================================   
 * Created [2009-4-27 下午11:32:55] by Jon.King 
 * ==================================================================  
 * TSS 
 * ================================================================== 
 * mailTo:jinpujun@hotmail.com
 * Copyright (c) Jon.King, 2009-2012 
 * ================================================================== 
*/

package com.jinhe.tss.core.common.license;

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;

import com.jinhe.tss.core.util.FileHelper;
import com.jinhe.tss.core.util.EasyUtils;
import com.jinhe.tss.core.util.URLUtil;

public class LicenseFactory {

    static String LICENSE_DIR = URLUtil.getClassesPath().getPath();
    static String PRIVATE_KEY_FILE = LICENSE_DIR + "/private.key";
    static String PUBLIC_KEY_FILE  = LICENSE_DIR + "/public.key";

    /**
     * 用私钥对license进行数据签名
     * @param license
     * @throws Exception
     */
    public static synchronized void sign(License license) throws Exception {
        String privateKey = FileHelper.readFile(new File(PRIVATE_KEY_FILE));
        KeyFactory keyFactory = KeyFactory.getInstance("DSA");
        PKCS8EncodedKeySpec privKeySpec = new PKCS8EncodedKeySpec(EasyUtils.decodeHex(privateKey.trim()));
        PrivateKey privKey = keyFactory.generatePrivate(privKeySpec);
        
        Signature sig = Signature.getInstance("SHA1withDSA");
        sig.initSign(privKey);
        sig.update(license.getFingerprint());
        
        license.licenseSignature = EasyUtils.encodeHex(sig.sign());
    }

    /**
     * 生成公钥、私钥对。公钥公开，注意保管好私钥（如果泄露，则有可能被hacker随意创建license）
     * @throws Exception
     */
    public static void generateKey() throws Exception {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
        keyGen.initialize(1024, random);
        KeyPair pair = keyGen.generateKeyPair();
        PrivateKey priv = pair.getPrivate();
        PublicKey pub = pair.getPublic();
        
        DataOutputStream out = new DataOutputStream(new FileOutputStream(PUBLIC_KEY_FILE));
        out.writeBytes(EasyUtils.encodeHex(pub.getEncoded()));
        out.close();
        
        out = new DataOutputStream(new FileOutputStream(PRIVATE_KEY_FILE));
        out.writeBytes(EasyUtils.encodeHex(priv.getEncoded()));
        out.close();
    }

    public static void main(String args[]) throws Exception {
        generateKey();
        
        License license = License.fromConfigFile("cpu.license");
        sign(license);
        System.out.println("signature=" + license.getLicenseSignature());
    }
}