本篇的主要內容為Java證書體系的實現。
請大家在閱讀本篇內容時先閱讀 Java加密技術（四），預先了解RSA加密算法。
在構建Java代碼實現前，我們需要完成證書的制作。
1.生成keyStroe文件
在命令行下執行以下命令：
Shell代碼
keytool -genkey -alias www.zlex.org -keyalg RSA -keystore d:\zlex.keystore
其中
-genkey表示生成密鑰
-alias指定別名，這裡是www.zlex.org
-keyalg指定算法，這裡是RSA
-keystore指定存儲位置，這裡是d:\zlex.keystore
在這裡我使用的密碼為 123456
控制台輸出：
Console代碼
輸入keystore密碼：
再次輸入新密碼:
您的名字與姓氏是什麼？
[Unknown]： www.zlex.org
您的組織單位名稱是什麼？
[Unknown]： zlex
您的組織名稱是什麼？
[Unknown]： zlex
您所在的城市或區域名稱是什麼？
[Unknown]： BJ
您所在的州或省份名稱是什麼？
[Unknown]： BJ
該單位的兩字母國家代碼是什麼
[Unknown]： CN
CN=www.zlex.org, OU=zlex, O=zlex, L=BJ, ST=BJ, C=CN 正確嗎？
[否]： Y
輸入<tomcat>的主密碼
（如果和 keystore 密碼相同，按回車）：
再次輸入新密碼:
這時，在D盤下會生成一個zlex.keystore的文件。
2.生成自簽名證書
光有keyStore文件是不夠的，還需要證書文件，證書才是直接提供給外界使用的公鑰憑證。
導出證書：
Shell代碼
keytool -export -keystore d：\zlex.keystore -alias www.zlex.org -file d：\zlex.cer -rfc
其中
-export指定為導出操作
-keystore指定keystore文件
-alias指定導出keystore文件中的別名
-file指向導出路徑
-rfc以文本格式輸出，也就是以BASE64編碼輸出
這裡的密碼是 123456
控制台輸出：
Console代碼
輸入keystore密碼：
保存在文件中的認證 <d:\zlex.cer>
當然，使用方是需要注冊證書的！
Ok，准備工作完成，開始Java實現！
通過java代碼實現如下：Coder類見 Java加密技術（一）
Java代碼
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;
/**
* 證書組件
*
* @author 梁棟
* @version 1.0
* @since 1.0
*/
public abstract class CertificateCoder extends Coder {
/**
* Java密鑰庫(Java Key Store，JKS)KEY_STORE
*/
public static final String KEY_STORE = "JKS";
public static final String X509 = "X.509";
/**
* 由KeyStore獲得私鑰
*
* @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獲得公鑰
*
* @param certificatePath
* @return
* @throws Exception
*/
private static PublicKey getPublicKey(String certificatePath)
throws Exception {
Certificate certificate = getCertificate(certificatePath);
PublicKey key = certificate.getPublicKey();
return key;
}
/**
* 獲得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;
}
/**
* 獲得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;
}
/**
* 獲得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;
}
/**
* 私鑰加密
*
* @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 {
// 取得私鑰
PrivateKey privateKey = getPrivateKey(keyStorePath, alias, password);
// 對數據加密
Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
return cipher.doFinal(data);
}
/**
* 私鑰解密
*
* @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 {
// 取得私鑰
PrivateKey privateKey = getPrivateKey(keyStorePath, alias, password);
// 對數據加密
Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return cipher.doFinal(data);
}
/**
* 公鑰加密
*
* @param data
* @param certificatePath
* @return
* @throws Exception
*/
public static byte[] encryptByPublicKey(byte[] data, String certificatePath)
throws Exception {
// 取得公鑰
PublicKey publicKey = getPublicKey(certificatePath);
// 對數據加密
Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
return cipher.doFinal(data);
}
/**
* 公鑰解密
*
* @param data
* @param certificatePath
* @return
* @throws Exception
*/
public static byte[] decryptByPublicKey(byte[] data, String certificatePath)
throws Exception {
// 取得公鑰
PublicKey publicKey = getPublicKey(certificatePath);
// 對數據加密
Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, publicKey);
return cipher.doFinal(data);
}
/**
* 驗證Certificate
*
* @param certificatePath
* @return
*/
public static boolean verifyCertificate(String certificatePath) {
return verifyCertificate(new Date(), certificatePath);
}
/**
* 驗證Certificate是否過期或無效
*
* @param date
* @param certificatePath
* @return
*/
public static boolean verifyCertificate(Date date, String certificatePath) {
boolean status = true;
try {
// 取得證書
Certificate certificate = getCertificate(certificatePath);
// 驗證證書是否過期或無效
status = verifyCertificate(date, certificate);
} catch (Exception e) {
status = false;
}
return status;
}
/**
* 驗證證書是否過期或無效
*
* @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;
}
/**
* 簽名
*
* @param keyStorePath
* @param alias
* @param password
*
* @return
* @throws Exception
*/
public static String sign(byte[] sign, String keyStorePath, String alias,
String password) throws Exception {
// 獲得證書
X509Certificate x509Certificate = (X509Certificate) getCertificate(
keyStorePath, alias, password);
// 獲取私鑰
KeyStore ks = getKeyStore(keyStorePath, password);
// 取得私鑰
PrivateKey privateKey = (PrivateKey) ks.getKey(alias, password
.toCharArray());
// 構建簽名
Signature signature = Signature.getInstance(x509Certificate
.getSigAlgName());
signature.initSign(privateKey);
signature.update(sign);
return encryptBASE64(signature.sign());
}
/**
* 驗證簽名
*
* @param data
* @param sign
* @param certificatePath
* @return
* @throws Exception
*/
public static boolean verify(byte[] data, String sign,
String certificatePath) throws Exception {
// 獲得證書
X509Certificate x509Certificate = (X509Certificate) getCertificate(certificatePath);
// 獲得公鑰
PublicKey publicKey = x509Certificate.getPublicKey();
// 構建簽名
Signature signature = Signature.getInstance(x509Certificate
.getSigAlgName());
signature.initVerify(publicKey);
signature.update(data);
return signature.verify(decryptBASE64(sign));
}
/**
* 驗證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;
}
/**
* 驗證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);
}
}
再給出一個測試類：
Java代碼
import static org.junit.Assert.*;
import org.junit.Test;
/**
*
* @author 梁棟
* @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";
@Test
public void test() throws Exception {
System.err.println("公鑰加密——私鑰解密");
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" + "解密後: " + outputStr);
// 驗證數據一致
assertArrayEquals(data, decrypt);
// 驗證證書有效
assertTrue(CertificateCoder.verifyCertificate(certificatePath));
}
@Test
public void testSign() throws Exception {
System.err.println("私鑰加密——公鑰解密");
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" + "解密後: " + outputStr);
assertEquals(inputStr, outputStr);
System.err.println("私鑰簽名——公鑰驗證簽名");
// 產生簽名
String sign = CertificateCoder.sign(encodedData, keyStorePath, alias,
password);
System.err.println("簽名:\r" + sign);
// 驗證簽名
boolean status = CertificateCoder.verify(encodedData, sign,
certificatePath);
System.err.println("狀態:\r" + status);
assertTrue(status);
}
}
控制台輸出：
Console代碼
公鑰加密——私鑰解密
加密前: Ceritificate
解密後: Ceritificate
私鑰加密——公鑰解密
加密前: sign
解密後: sign
私鑰簽名——公鑰驗證簽名
簽名:
pqBn5m6PJlfOjH0A6U2o2mUmBsfgyEY1NWCbiyA/I5Gc3gaVNVIdj/zkGNZRqTjhf3+J9a9z9EI7
6F2eWYd7punHx5oh6hfNgcKbVb52EfItl4QEN+djbXiPynn07+Lbg1NOjULnpEd6ZhLP1YwrEAuM
OfvX0e7/wplxLbySaKQ=
狀態:
true
由此完成了證書驗證體系！
