DSACoder.java

package com.mtools.core.plugin.security;

import java.security.Key;
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.interfaces.DSAPrivateKey;
import java.security.interfaces.DSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
 
/**
 * DSA安全编码组件
 * 
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
public abstract class DSACoder extends Coder {
 
    public static final String ALGORITHM = "DSA";
 
    /**
     * 默认密钥字节数
     * 
     * <pre>
     * DSA 
     * Default Keysize 1024  
     * Keysize must be a multiple of 64, ranging from 512 to 1024 (inclusive).
     * </pre>
     */
    private static final int KEY_SIZE = 1024;
 
    /**
     * 默认种子
     */
    private static final String DEFAULT_SEED = "0f22507a10bbddd07d8a3082122966e3";
 
    private static final String PUBLIC_KEY = "DSAPublicKey";
    private static final String PRIVATE_KEY = "DSAPrivateKey";
 
    /**
     * 用私钥对信息生成数字签名
     * 
     * @param data
     *            加密数据
     * @param privateKey
     *            私钥
     * 
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBASE64(privateKey);
 
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
 
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
 
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
 
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(keyFactory.getAlgorithm());
        signature.initSign(priKey);
        signature.update(data);
 
        return encryptBASE64(signature.sign());
    }
 
    /**
     * 校验数字签名
     * 
     * @param data
     *            加密数据
     * @param publicKey
     *            公钥
     * @param sign
     *            数字签名
     * 
     * @return 校验成功返回true 失败返回false
     * @throws Exception
     * 
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
 
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBASE64(publicKey);
 
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
 
        // ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
 
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
 
        Signature signature = Signature.getInstance(keyFactory.getAlgorithm());
        signature.initVerify(pubKey);
        signature.update(data);
 
        // 验证签名是否正常
        return signature.verify(decryptBASE64(sign));
    }
 
    /**
     * 生成密钥
     * 
     * @param seed
     *            种子
     * @return 密钥对象
     * @throws Exception
     */
    public static Map<String, Object> initKey(String seed) throws Exception {
        KeyPairGenerator keygen = KeyPairGenerator.getInstance(ALGORITHM);
        // 初始化随机产生器
        SecureRandom secureRandom = new SecureRandom();
        secureRandom.setSeed(seed.getBytes());
        keygen.initialize(KEY_SIZE, secureRandom);
 
        KeyPair keys = keygen.genKeyPair();
 
        DSAPublicKey publicKey = (DSAPublicKey) keys.getPublic();
        DSAPrivateKey privateKey = (DSAPrivateKey) keys.getPrivate();
 
        Map<String, Object> map = new HashMap<String, Object>(2);
        map.put(PUBLIC_KEY, publicKey);
        map.put(PRIVATE_KEY, privateKey);
 
        return map;
    }
 
    /**
     * 默认生成密钥
     * 
     * @return 密钥对象
     * @throws Exception
     */
    public static Map<String, Object> initKey() throws Exception {
        return initKey(DEFAULT_SEED);
    }
 
    /**
     * 取得私钥
     * 
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
 
        return encryptBASE64(key.getEncoded());
    }
 
    /**
     * 取得公钥
     * 
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
 
        return encryptBASE64(key.getEncoded());
    }
}