在构建Java代码实现前,我们需要完成证书的制作。 
1.生成keyStroe文件 
在命令行下执行以下命令:

Shell代码

keytool -genkey -validity 36000 -alias www.zlex.org -keyalg RSA -keystore d:\zlex.keystore

其中 
-genkey表示生成密钥 
-validity指定证书有效期,这里是36000天 
-alias指定别名,这里是www.zlex.org 
-keyalg指定算法,这里是RSA 
-keystore指定存储位置,这里是d:\zlex.keystore 

在这里我使用的密码为 123456 

控制台输出: 

Console代码

输入keystore密码:
再次输入新密码:
您的名字与姓氏是什么?
  [Unknown]:  www.zlex.org
您的组织单位名称是什么?
  [Unknown]:  zlex
您的组织名称是什么?
  [Unknown]:  zlex
您所在的城市或区域名称是什么?
  [Unknown]:  BJ
您所在的州或省份名称是什么?
  [Unknown]:  BJ
该单位的两字母国家代码是什么
  [Unknown]:  CN
CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN 正确吗?
  [否]:  Y

输入<tomcat>的主密码
        (如果和 keystore 密码相同,按回车):
再次输入新密码:

这时,在D盘下会生成一个zlex.keystore的文件。 

2.生成自签名证书 
光有keyStore文件是不够的,还需要证书文件,证书才是直接提供给外界使用的公钥凭证。 
导出证书: 

Shell代码

keytool -export -keystore d:\zlex.keystore -alias www.zlex.org -file d:\zlex.cer -rfc

其中 
-export指定为导出操作 
-keystore指定keystore文件 
-alias指定导出keystore文件中的别名 
-file指向导出路径 
-rfc以文本格式输出,也就是以BASE64编码输出 
这里的密码是 123456 

控制台输出: 

Console代码

输入keystore密码:
保存在文件中的认证 <d:\zlex.cer>

当然,使用方是需要导入证书的! 
可以通过自签名证书完成CAS单点登录系统的构建!

Ok,准备工作完成,开始Java实现! 

通过java代码实现如下:Coder类见 Java加密算法(一)

Java代码

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;

/**
 *
 * 证书组件
 * 
 */
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";

	/**
	 * 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);
	}
}

再给出一个测试类: 

Java代码 

import static org.junit.Assert.*;

import org.junit.Test;

/**
 * 
 * 数字证书测试
 * 
 */
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";

	@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);

	}
}

控制台输出: 

Console代码

公钥加密——私钥解密
加密前: Ceritificate

解密后: Ceritificate

私钥加密——公钥解密
加密前: sign

解密后: sign
私钥签名——公钥验证签名
签名:
pqBn5m6PJlfOjH0A6U2o2mUmBsfgyEY1NWCbiyA/I5Gc3gaVNVIdj/zkGNZRqTjhf3+J9a9z9EI7
6F2eWYd7punHx5oh6hfNgcKbVb52EfItl4QEN+djbXiPynn07+Lbg1NOjULnpEd6ZhLP1YwrEAuM
OfvX0e7/wplxLbySaKQ=

状态:
true

由此完成了证书验证体系!

同样,我们可以对代码做签名——代码签名!

通过工具JarSigner可以完成代码签名。 
这里我们对tools.jar做代码签名,命令如下: 

Shell代码

jarsigner -storetype jks -keystore zlex.keystore -verbose tools.jar www.zlex.org

控制台输出: 

Console代码

输入密钥库的口令短语:
 正在更新: META-INF/WWW_ZLEX.SF
 正在更新: META-INF/WWW_ZLEX.RSA
  正在签名: org/zlex/security/Security.class
  正在签名: org/zlex/tool/Main$1.class
  正在签名: org/zlex/tool/Main$2.class
  正在签名: org/zlex/tool/Main.class

警告:
签名者证书将在六个月内过期。

此时,我们可以对签名后的jar做验证!

验证tools.jar,命令如下: 

Shell代码

jarsigner -verify -verbose -certs tools.jar

控制台输出: 

Console代码 

402 Sat Jun 20 16:25:14 CST 2009 META-INF/MANIFEST.MF
         532 Sat Jun 20 16:25:14 CST 2009 META-INF/WWW_ZLEX.SF
         889 Sat Jun 20 16:25:14 CST 2009 META-INF/WWW_ZLEX.RSA
sm       590 Wed Dec 10 13:03:42 CST 2008 org/zlex/security/Security.class

      X.509, CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
      [证书将在 09-9-18 下午3:27 到期]

sm       705 Tue Dec 16 18:00:56 CST 2008 org/zlex/tool/Main$1.class

      X.509, CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
      [证书将在 09-9-18 下午3:27 到期]

sm       779 Tue Dec 16 18:00:56 CST 2008 org/zlex/tool/Main$2.class

      X.509, CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
      [证书将在 09-9-18 下午3:27 到期]

sm     12672 Tue Dec 16 18:00:56 CST 2008 org/zlex/tool/Main.class

      X.509, CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN
      [证书将在 09-9-18 下午3:27 到期]


  s = 已验证签名
  m = 在清单中列出条目
  k = 在密钥库中至少找到了一个证书
  i = 在身份作用域内至少找到了一个证书

jar 已验证。

警告:
此 jar 包含签名者证书将在六个月内过期的条目。

代码签名认证的用途主要是对发布的软件做验证,支持 Sun Java .jar (Java Applet) 文件(J2SE)和 J2ME MIDlet Suite 文件。