Java加密技术（九）——初探SSL

 

    在Java加密技术（八）中，我们模拟了一个基于RSA非对称加密网络的安全通信。现在我们深度了解一下现有的安全网络通信——SSL。 
    我们需要构建一个由CA机构签发的有效证书，这里我们使用上文中生成的自签名证书zlex.cer 
    这里，我们将证书导入到我们的密钥库。 

keytool -import -alias www.zlex.org -file d:/zlex.cer -keystore d:/zlex.keystore

其中 
-import表示导入 
-alias指定别名，这里是www.zlex.org 
-file指定算法，这里是d:/zlex.cer 
-keystore指定存储位置，这里是d:/zlex.keystore 
在这里我使用的密码为654321 

控制台输出： 

输入keystore密码：
再次输入新密码:
所有者:CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
签发人:CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
序列号:4a1e48df
有效期: Thu May 28 16:18:39 CST 2009 至Wed Aug 26 16:18:39 CST 2009
证书指纹:
         MD5:19:CA:E6:36:E2:DF:AD:96:31:97:2F:A9:AD:FC:37:6A
         SHA1:49:88:30:59:29:45:F1:69:CA:97:A9:6D:8A:CF:08:D2:C3:D5:C0:C4
         签名算法名称:SHA1withRSA
         版本: 3
信任这个认证？ [否]：  y
认证已添加至keystore中

OK，最复杂的准备工作已经完成。 
接下来我们将域名www.zlex.org定位到本机上。打开C:\Windows\System32\drivers\etc\hosts文件，将www.zlex.org绑定在本机上。在文件末尾追加127.0.0.1       www.zlex.org。现在通过地址栏访问http://www.zlex.org，或者通过ping命令，如果能够定位到本机，域名映射就搞定了。 
现在，配置tomcat。先将zlex.keystore拷贝到tomcat的conf目录下，然后配置server.xml。将如下内容加入配置文件

<Connector
    SSLEnabled="true"
    URIEncoding="UTF-8"
    clientAuth="false"
    keystoreFile="conf/zlex.keystore"
    keystorePass="123456"
    maxThreads="150"
    port="443"
    protocol="HTTP/1.1"
    scheme="https"
    secure="true"
    sslProtocol="TLS" />

注意clientAuth="false"测试阶段，置为false，正式使用时建议使用true。现在启动tomcat，访问https://www.zlex.org/。 
显然，证书未能通过认证，这个时候你可以选择安装证书（上文中的zlex.cer文件就是证书），作为受信任的根证书颁发机构导入，再次重启浏览器（IE，其他浏览器对于域名www.zlex.org不支持本地方式访问），访问https://www.zlex.org/，你会看到地址栏中会有个小锁，就说明安装成功。所有的浏览器联网操作已经在RSA加密解密系统的保护之下了。但似乎我们感受不到。 
这个时候很多人开始怀疑，如果我们要手工做一个这样的https的访问是不是需要把浏览器的这些个功能都实现呢？不需要！ 

接着上篇内容，给出如下代码实现： 

import java.io.FileInputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Date;

import javax.crypto.Cipher;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManagerFactory;

/**
 * 证书组件
 *
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
public abstract class CertificateCoder extends Coder {

    /**
     * Java密钥库(Java Key Store，JKS)KEY_STORE
     */
    public static final String KEY_STORE = "JKS";

    public static final String X509 = "X.509";
    public static final String SunX509 = "SunX509";
    public static final String SSL = "SSL";

    /**
     * 由KeyStore获得私钥
     *
     * @param keyStorePath
     * @param alias
     * @param password
     * @return
     * @throws Exception
     */
    private static PrivateKey getPrivateKey(String keyStorePath, String alias,
            String password) throws Exception {
        KeyStore ks = getKeyStore(keyStorePath, password);
        PrivateKey key = (PrivateKey) ks.getKey(alias, password.toCharArray());
        return key;
    }

    /**
     * 由Certificate获得公钥
     *
     * @param certificatePath
     * @return
     * @throws Exception
     */
    private static PublicKey getPublicKey(String certificatePath)
            throws Exception {
        Certificate certificate = getCertificate(certificatePath);
        PublicKey key = certificate.getPublicKey();
        return key;
    }

    /**
     * 获得Certificate
     *
     * @param certificatePath
     * @return
     * @throws Exception
     */
    private static Certificate getCertificate(String certificatePath)
            throws Exception {
        CertificateFactory certificateFactory = CertificateFactory
                .getInstance(X509);
        FileInputStream in = new FileInputStream(certificatePath);

        Certificate certificate = certificateFactory.generateCertificate(in);
        in.close();

        return certificate;
    }

    /**
     * 获得Certificate
     *
     * @param keyStorePath
     * @param alias
     * @param password
     * @return
     * @throws Exception
     */
    private static Certificate getCertificate(String keyStorePath,
            String alias, String password) throws Exception {
        KeyStore ks = getKeyStore(keyStorePath, password);
        Certificate certificate = ks.getCertificate(alias);

        return certificate;
    }

    /**
     * 获得KeyStore
     *
     * @param keyStorePath
     * @param password
     * @return
     * @throws Exception
     */
    private static KeyStore getKeyStore(String keyStorePath, String password)
            throws Exception {
        FileInputStream is = new FileInputStream(keyStorePath);
        KeyStore ks = KeyStore.getInstance(KEY_STORE);
        ks.load(is, password.toCharArray());
        is.close();
        return ks;
    }

    /**
     * 私钥加密
     *
     * @param data
     * @param keyStorePath
     * @param alias
     * @param password
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String keyStorePath,
            String alias, String password) throws Exception {
        // 取得私钥
        PrivateKey privateKey = getPrivateKey(keyStorePath, alias, password);

        // 对数据加密
        Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);

        return cipher.doFinal(data);

    }

    /**
     * 私钥解密
     *
     * @param data
     * @param keyStorePath
     * @param alias
     * @param password
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] data, String keyStorePath,
            String alias, String password) throws Exception {
        // 取得私钥
        PrivateKey privateKey = getPrivateKey(keyStorePath, alias, password);

        // 对数据加密
        Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        return cipher.doFinal(data);

    }

    /**
     * 公钥加密
     *
     * @param data
     * @param certificatePath
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String certificatePath)
            throws Exception {

        // 取得公钥
        PublicKey publicKey = getPublicKey(certificatePath);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);

        return cipher.doFinal(data);

    }

    /**
     * 公钥解密
     *
     * @param data
     * @param certificatePath
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data, String certificatePath)
            throws Exception {
        // 取得公钥
        PublicKey publicKey = getPublicKey(certificatePath);

        // 对数据加密
        Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);

        return cipher.doFinal(data);

    }

    /**
     * 验证Certificate
     *
     * @param certificatePath
     * @return
     */
    public static boolean verifyCertificate(String certificatePath) {
        return verifyCertificate(new Date(), certificatePath);
    }

    /**
     * 验证Certificate是否过期或无效
     *
     * @param date
     * @param certificatePath
     * @return
     */
    public static boolean verifyCertificate(Date date, String certificatePath) {
        boolean status = true;
        try {
            // 取得证书
            Certificate certificate = getCertificate(certificatePath);
            // 验证证书是否过期或无效
            status = verifyCertificate(date, certificate);
        } catch (Exception e) {
            status = false;
        }
        return status;
    }

    /**
     * 验证证书是否过期或无效
     *
     * @param date
     * @param certificate
     * @return
     */
    private static boolean verifyCertificate(Date date, Certificate certificate) {
        boolean status = true;
        try {
            X509Certificate x509Certificate = (X509Certificate) certificate;
            x509Certificate.checkValidity(date);
        } catch (Exception e) {
            status = false;
        }
        return status;
    }

    /**
     * 签名
     *
     * @param keyStorePath
     * @param alias
     * @param password
     *
     * @return
     * @throws Exception
     */
    public static String sign(byte[] sign, String keyStorePath, String alias,
            String password) throws Exception {
        // 获得证书
        X509Certificate x509Certificate = (X509Certificate) getCertificate(
                keyStorePath, alias, password);
        // 获取私钥
        KeyStore ks = getKeyStore(keyStorePath, password);
        // 取得私钥
        PrivateKey privateKey = (PrivateKey) ks.getKey(alias, password
                .toCharArray());

        // 构建签名
        Signature signature = Signature.getInstance(x509Certificate
                .getSigAlgName());
        signature.initSign(privateKey);
        signature.update(sign);
        return encryptBASE64(signature.sign());
    }

    /**
     * 验证签名
     *
     * @param data
     * @param sign
     * @param certificatePath
     * @return
     * @throws Exception
     */
    public static boolean verify(byte[] data, String sign,
            String certificatePath) throws Exception {
        // 获得证书
        X509Certificate x509Certificate = (X509Certificate) getCertificate(certificatePath);
        // 获得公钥
        PublicKey publicKey = x509Certificate.getPublicKey();
        // 构建签名
        Signature signature = Signature.getInstance(x509Certificate
                .getSigAlgName());
        signature.initVerify(publicKey);
        signature.update(data);

        return signature.verify(decryptBASE64(sign));

    }

    /**
     * 验证Certificate
     *
     * @param keyStorePath
     * @param alias
     * @param password
     * @return
     */
    public static boolean verifyCertificate(Date date, String keyStorePath,
            String alias, String password) {
        boolean status = true;
        try {
            Certificate certificate = getCertificate(keyStorePath, alias,
                    password);
            status = verifyCertificate(date, certificate);
        } catch (Exception e) {
            status = false;
        }
        return status;
    }

    /**
     * 验证Certificate
     *
     * @param keyStorePath
     * @param alias
     * @param password
     * @return
     */
    public static boolean verifyCertificate(String keyStorePath, String alias,
            String password) {
        return verifyCertificate(new Date(), keyStorePath, alias, password);
    }

    /**
     * 获得SSLSocektFactory
     *
     * @param password
     *            密码
     * @param keyStorePath
     *            密钥库路径
     *
     * @param trustKeyStorePath
     *            信任库路径
     * @return
     * @throws Exception
     */
    private static SSLSocketFactory getSSLSocketFactory(String password,
            String keyStorePath, String trustKeyStorePath) throws Exception {
        // 初始化密钥库
        KeyManagerFactory keyManagerFactory = KeyManagerFactory
                .getInstance(SunX509);
        KeyStore keyStore = getKeyStore(keyStorePath, password);
        keyManagerFactory.init(keyStore, password.toCharArray());

        // 初始化信任库
        TrustManagerFactory trustManagerFactory = TrustManagerFactory
                .getInstance(SunX509);
        KeyStore trustkeyStore = getKeyStore(trustKeyStorePath, password);
        trustManagerFactory.init(trustkeyStore);

        // 初始化SSL上下文
        SSLContext ctx = SSLContext.getInstance(SSL);
        ctx.init(keyManagerFactory.getKeyManagers(), trustManagerFactory
                .getTrustManagers(), null);
        SSLSocketFactory sf = ctx.getSocketFactory();

        return sf;
    }

    /**
     * 为HttpsURLConnection配置SSLSocketFactory
     *
     * @param conn
     *            HttpsURLConnection
     * @param password
     *            密码
     * @param keyStorePath
     *            密钥库路径
     *
     * @param trustKeyStorePath
     *            信任库路径
     * @throws Exception
     */
    public static void configSSLSocketFactory(HttpsURLConnection conn,
            String password, String keyStorePath, String trustKeyStorePath)
            throws Exception {
        conn.setSSLSocketFactory(getSSLSocketFactory(password, keyStorePath,
                trustKeyStorePath));
    }
}

增加了configSSLSocketFactory方法供外界调用，该方法为HttpsURLConnection配置了SSLSocketFactory。当HttpsURLConnection配置了SSLSocketFactory后，我们就可以通过HttpsURLConnection的getInputStream、getOutputStream，像往常使用HttpURLConnection做操作了。尤其要说明一点，未配置SSLSocketFactory前，HttpsURLConnection的getContentLength()获得值永远都是-1。 

给出相应测试类： 

import static org.junit.Assert.*;

import java.io.DataInputStream;
import java.io.InputStream;
import java.net.URL;

import javax.net.ssl.HttpsURLConnection;

import org.junit.Test;

/**
 *
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
public class CertificateCoderTest {
    private String password = "123456";
    private String alias = "www.zlex.org";
    private String certificatePath = "d:/zlex.cer";
    private String keyStorePath = "d:/zlex.keystore";
    private String clientKeyStorePath = "d:/zlex-client.keystore";
    private String clientPassword = "654321";

    @Test
    public void test() throws Exception {
        System.err.println("公钥加密——私钥解密");
        String inputStr = "Ceritifcate";
        byte[] data = inputStr.getBytes();

        byte[] encrypt = CertificateCoder.encryptByPublicKey(data,
                certificatePath);

        byte[] decrypt = CertificateCoder.decryptByPrivateKey(encrypt,
                keyStorePath, alias, password);
        String outputStr = new String(decrypt);

        System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);

        // 验证数据一致
        assertArrayEquals(data, decrypt);

        // 验证证书有效
        assertTrue(CertificateCoder.verifyCertificate(certificatePath));

    }

    @Test
    public void testSign() throws Exception {
        System.err.println("私钥加密——公钥解密");

        String inputStr = "sign";
        byte[] data = inputStr.getBytes();

        byte[] encodedData = CertificateCoder.encryptByPrivateKey(data,
                keyStorePath, alias, password);

        byte[] decodedData = CertificateCoder.decryptByPublicKey(encodedData,
                certificatePath);

        String outputStr = new String(decodedData);
        System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
        assertEquals(inputStr, outputStr);

        System.err.println("私钥签名——公钥验证签名");
        // 产生签名
        String sign = CertificateCoder.sign(encodedData, keyStorePath, alias,
                password);
        System.err.println("签名:\r" + sign);

        // 验证签名
        boolean status = CertificateCoder.verify(encodedData, sign,
                certificatePath);
        System.err.println("状态:\r" + status);
        assertTrue(status);

    }

    @Test
    public void testHttps() throws Exception {
        URL url = new URL("https://www.zlex.org/examples/");
        HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();

        conn.setDoInput(true);
        conn.setDoOutput(true);

        CertificateCoder.configSSLSocketFactory(conn, clientPassword,
                clientKeyStorePath, clientKeyStorePath);

        InputStream is = conn.getInputStream();

        int length = conn.getContentLength();

        DataInputStream dis = new DataInputStream(is);
        byte[] data = new byte[length];
        dis.readFully(data);

        dis.close();
        System.err.println(new String(data));
        conn.disconnect();
    }
}

注意testHttps方法，几乎和我们往常做HTTP访问没有差别，我们来看控制台输出： 

<!--
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD><TITLE>Apache Tomcat Examples</TITLE>
<META http-equiv=Content-Type content="text/html">
</HEAD>
<BODY>
<P>
<H3>Apache Tomcat Examples</H3>
<P></P>
<ul>
<li><a href="servlets">Servlets examples</a></li>
<li><a href="jsp">JSP Examples</a></li>
</ul>
</BODY></HTML>

通过浏览器直接访问https://www.zlex.org/examples/你也会获得上述内容。也就是说应用甲方作为服务器构建tomcat服务，乙方可以通过上述方式访问甲方受保护的SSL应用，并且不需要考虑具体的加密解密问题。甲乙双方可以经过相应配置，通过双方的tomcat配置有效的SSL服务，简化上述代码实现，完全通过证书配置完成SSL双向认证！