dsa.java.svn-base

多线程加密聊天室,支持多线程客户端链接服务器端

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package mytools;

import java.io.*;
import java.security.*;
import java.security.spec.*;

/**
 *
 * @author DJ尐舞
 */
public class DSA {

    /**
     * 认证签名
     * @param content 内容
     * @param signed 签名
     * @param encodedPubKey 经过X.509编码的公钥字节数组
     * @return 返回只是认证结果
     */
    public static boolean validate(byte[] content, byte[] signed, byte[] encodedPubKey) {
        // 第三步
        // 其他人通过公共方式得到此户的公钥和文件
        // 其他人用此户的公钥,对文件进行检查,如果成功说明是此用户发布的信息.
        //
        try {
            //通过密钥工厂将编码过的公钥解码得到公钥
            X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(encodedPubKey);
            System.out.println("公钥:"+DSA.byte2hex(encodedPubKey));
//            X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(generatekey().getPublic().getEncoded());
            KeyFactory keyFactory = KeyFactory.getInstance("DSA");
            PublicKey pubkey = keyFactory.generatePublic(pubKeySpec);

            java.security.Signature signetcheck = java.security.Signature.getInstance("DSA");
            signetcheck.initVerify(pubkey);
            signetcheck.update(content);
            if (signetcheck.verify(signed)) {
                System.out.println("签名正常");
                return true;
            }
        } catch (java.lang.Exception e) {
            e.printStackTrace();
        }
        System.out.println("签名失败");
        return false;
    }

    /**
     * 对内容进行签名
     * @param content 要进行签名的内容
     * @return 签名的字节数组
     * @throws java.lang.Exception 签名过程中的所有异常
     */
    public static byte[] sign(byte[] content, String userName) throws java.lang.Exception {//通过从目录下读取私钥prikey.dat来签名信息
        java.io.ObjectInputStream in = new java.io.ObjectInputStream(new java.io.FileInputStream(userName + ".prikey"));
        PrivateKey prikey = (PrivateKey) in.readObject();
        in.close();

        // 用私钥对信息生成数字签名
        java.security.Signature signet = java.security.Signature.getInstance("DSA");
        signet.initSign(prikey);
        signet.update(content);

//        System.out.println("signed(签名内容)=" + byte2hex(signed));
        return signet.sign(); // 对信息的数字签名
    }

    /**
     * 生成密钥对
     * @return 密钥对
     * @throws java.security.NoSuchAlgorithmException 找不到DSA算法
     */
    public static KeyPair generatekey() throws NoSuchAlgorithmException {

        KeyPairGenerator keygen = KeyPairGenerator.getInstance("DSA");
        keygen.initialize(512);//初始化512位的密钥
        return keygen.genKeyPair();

    }

    /**
     * 保存私钥
     * @param encodedPriKey
     * @return 是否保存成功
     */
    public static boolean savePrikey(byte[] encodedPriKey, String userName) {

        java.io.ObjectOutputStream out = null;
        try {
            //对于DSA的私钥是用PKCS#8编码
            PKCS8EncodedKeySpec priKeySpec = new PKCS8EncodedKeySpec(encodedPriKey);
            KeyFactory keyFactory = KeyFactory.getInstance("DSA");
            PrivateKey prikey = keyFactory.generatePrivate(priKeySpec);
            out = new java.io.ObjectOutputStream(new java.io.FileOutputStream(userName + ".prikey"));
            out.writeObject(prikey);
            out.close();
            return true;
        } catch (IOException ex) {
            ex.printStackTrace();
            System.out.println("保存私钥失败");
        } catch (InvalidKeySpecException ex) {
            ex.printStackTrace();
            System.out.println("保存私钥失败:密钥无效");
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
            System.out.println("保存私钥失败:找不到DSA算法");
        } finally {
            try {
                out.close();
            } catch (IOException ex) {
            }
        }
        return false;
    }

    /**
     * 将字节数组转换为十六进制字符串
     * @param 字节数组
     * @return 十六进制数字符串
     */
    public static String byte2hex(byte[] b) {
        String hs = "";
        String stmp = "";
        for (int n = 0; n < b.length; n++) {
            stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
            if (stmp.length() == 1) {
                hs = hs + "0" + stmp;
            } else {
                hs = hs + stmp;
            }
            if (n < b.length - 1) {
                hs = hs + ":";
            }
        }
        return hs.toUpperCase();
    }
}
//    public static boolean generatekey(byte[] encodedPubkey, byte[] encodedPrikey) {
//        try {
//            KeyPairGenerator keygen = KeyPairGenerator.getInstance("DSA");
//            keygen.initialize(512);//初始化512位的密钥
//            KeyPair keys = keygen.genKeyPair();
//            PublicKey pubkey = keys.getPublic();
//            PrivateKey prikey = keys.getPrivate();
//
//            java.io.ObjectOutputStream out = new java.io.ObjectOutputStream(
//                    new java.io.FileOutputStream("prikey.dat"));
//            out.writeObject(prikey);
//            out.close();
//            System.out.println("创建私钥成功");
//            out = new java.io.ObjectOutputStream(new java.io.FileOutputStream(
//                    "pubkey.dat"));
//            out.writeObject(pubkey);
//            out.close();
//            System.out.println("创建公钥成功");
//            System.out.println("生成密钥对成功");
//            return true;
//        } catch (java.lang.Exception e) {
//            e.printStackTrace();
//            System.out.println("生成密钥对失败");
//            return false;
//        }
//
//    }