Java加密技术（六）——数字签名算法DSA

接下来我们介绍DSA数字签名，非对称加密的另一种实现。
DSA
DSA-Digital Signature Algorithm 是Schnorr和ElGamal签名算法的变种，被美国NIST作为DSS(DigitalSignature Standard)。简单的说，这是一种更高级的验证方式，用作数字签名。不单单只有公钥、私钥，还有数字签名。私钥加密生成数字签名，公钥验证数据及签名。如果数据和签名不匹配则认为验证失败！数字签名的作用就是校验数据在传输过程中不被修改。数字签名，是单向加密的升级！

1. 
2. 

通过java代码实现如下： Coder类见 Java加密技术（一）

Java代码  

1. import java.security.Key;  
2. import java.security.KeyFactory;  
3. import java.security.KeyPair;  
4. import java.security.KeyPairGenerator;  
5. import java.security.PrivateKey;  
6. import java.security.PublicKey;  
7. import java.security.SecureRandom;  
8. import java.security.Signature;  
9. import java.security.interfaces.DSAPrivateKey;  
10. import java.security.interfaces.DSAPublicKey;  
11. import java.security.spec.PKCS8EncodedKeySpec;  
12. import java.security.spec.X509EncodedKeySpec;  
13. import java.util.HashMap;  
14. import java.util.Map;  
15.   
16. /** 
17.  * DSA安全编码组件 
18.  *  
19.  * @author 梁栋 
20.  * @version 1.0 
21.  * @since 1.0 
22.  */  
23. public abstract class DSACoder extends Coder {  
24.   
25.     public static final String ALGORITHM = "DSA";  
26.   
27.     /** 
28.      * 默认密钥字节数 
29.      *  
30.      * <pre> 
31.      * DSA  
32.      * Default Keysize 1024   
33.      * Keysize must be a multiple of 64, ranging from 512 to 1024 (inclusive). 
34.      * </pre> 
35.      */  
36.     private static final int KEY_SIZE = 1024;  
37.   
38.     /** 
39.      * 默认种子 
40.      */  
41.     private static final String DEFAULT_SEED = "0f22507a10bbddd07d8a3082122966e3";  
42.   
43.     private static final String PUBLIC_KEY = "DSAPublicKey";  
44.     private static final String PRIVATE_KEY = "DSAPrivateKey";  
45.   
46.     /** 
47.      * 用私钥对信息生成数字签名 
48.      *  
49.      * @param data 
50.      *            加密数据 
51.      * @param privateKey 
52.      *            私钥 
53.      *  
54.      * @return 
55.      * @throws Exception 
56.      */  
57.     public static String sign(byte[] data, String privateKey) throws Exception {  
58.         // 解密由base64编码的私钥  
59.         byte[] keyBytes = decryptBASE64(privateKey);  
60.   
61.         // 构造PKCS8EncodedKeySpec对象  
62.         PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);  
63.   
64.         // KEY_ALGORITHM 指定的加密算法  
65.         KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);  
66.   
67.         // 取私钥匙对象  
68.         PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);  
69.   
70.         // 用私钥对信息生成数字签名  
71.         Signature signature = Signature.getInstance(keyFactory.getAlgorithm());  
72.         signature.initSign(priKey);  
73.         signature.update(data);  
74.   
75.         return encryptBASE64(signature.sign());  
76.     }  
77.   
78.     /** 
79.      * 校验数字签名 
80.      *  
81.      * @param data 
82.      *            加密数据 
83.      * @param publicKey 
84.      *            公钥 
85.      * @param sign 
86.      *            数字签名 
87.      *  
88.      * @return 校验成功返回true 失败返回false 
89.      * @throws Exception 
90.      *  
91.      */  
92.     public static boolean verify(byte[] data, String publicKey, String sign)  
93.             throws Exception {  
94.   
95.         // 解密由base64编码的公钥  
96.         byte[] keyBytes = decryptBASE64(publicKey);  
97.   
98.         // 构造X509EncodedKeySpec对象  
99.         X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);  
100.   
101.         // ALGORITHM 指定的加密算法  
102.         KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);  
103.   
104.         // 取公钥匙对象  
105.         PublicKey pubKey = keyFactory.generatePublic(keySpec);  
106.   
107.         Signature signature = Signature.getInstance(keyFactory.getAlgorithm());  
108.         signature.initVerify(pubKey);  
109.         signature.update(data);  
110.   
111.         // 验证签名是否正常  
112.         return signature.verify(decryptBASE64(sign));  
113.     }  
114.   
115.     /** 
116.      * 生成密钥 
117.      *  
118.      * @param seed 
119.      *            种子 
120.      * @return 密钥对象 
121.      * @throws Exception 
122.      */  
123.     public static Map<String, Object> initKey(String seed) throws Exception {  
124.         KeyPairGenerator keygen = KeyPairGenerator.getInstance(ALGORITHM);  
125.         // 初始化随机产生器  
126.         SecureRandom secureRandom = new SecureRandom();  
127.         secureRandom.setSeed(seed.getBytes());  
128.         keygen.initialize(KEY_SIZE, secureRandom);  
129.   
130.         KeyPair keys = keygen.genKeyPair();  
131.   
132.         DSAPublicKey publicKey = (DSAPublicKey) keys.getPublic();  
133.         DSAPrivateKey privateKey = (DSAPrivateKey) keys.getPrivate();  
134.   
135.         Map<String, Object> map = new HashMap<String, Object>(2);  
136.         map.put(PUBLIC_KEY, publicKey);  
137.         map.put(PRIVATE_KEY, privateKey);  
138.   
139.         return map;  
140.     }  
141.   
142.     /** 
143.      * 默认生成密钥 
144.      *  
145.      * @return 密钥对象 
146.      * @throws Exception 
147.      */  
148.     public static Map<String, Object> initKey() throws Exception {  
149.         return initKey(DEFAULT_SEED);  
150.     }  
151.   
152.     /** 
153.      * 取得私钥 
154.      *  
155.      * @param keyMap 
156.      * @return 
157.      * @throws Exception 
158.      */  
159.     public static String getPrivateKey(Map<String, Object> keyMap)  
160.             throws Exception {  
161.         Key key = (Key) keyMap.get(PRIVATE_KEY);  
162.   
163.         return encryptBASE64(key.getEncoded());  
164.     }  
165.   
166.     /** 
167.      * 取得公钥 
168.      *  
169.      * @param keyMap 
170.      * @return 
171.      * @throws Exception 
172.      */  
173.     public static String getPublicKey(Map<String, Object> keyMap)  
174.             throws Exception {  
175.         Key key = (Key) keyMap.get(PUBLIC_KEY);  
176.   
177.         return encryptBASE64(key.getEncoded());  
178.     }  
179. }  

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());
	}
}

再给出一个测试类：

Java代码  

1. import static org.junit.Assert.*;  
2.   
3. import java.util.Map;  
4.   
5. import org.junit.Test;  
6.   
7. /** 
8.  *  
9.  * @author 梁栋 
10.  * @version 1.0 
11.  * @since 1.0 
12.  */  
13. public class DSACoderTest {  
14.   
15.     @Test  
16.     public void test() throws Exception {  
17.         String inputStr = "abc";  
18.         byte[] data = inputStr.getBytes();  
19.   
20.         // 构建密钥  
21.         Map<String, Object> keyMap = DSACoder.initKey();  
22.   
23.         // 获得密钥  
24.         String publicKey = DSACoder.getPublicKey(keyMap);  
25.         String privateKey = DSACoder.getPrivateKey(keyMap);  
26.   
27.         System.err.println("公钥:\r" + publicKey);  
28.         System.err.println("私钥:\r" + privateKey);  
29.   
30.         // 产生签名  
31.         String sign = DSACoder.sign(data, privateKey);  
32.         System.err.println("签名:\r" + sign);  
33.   
34.         // 验证签名  
35.         boolean status = DSACoder.verify(data, publicKey, sign);  
36.         System.err.println("状态:\r" + status);  
37.         assertTrue(status);  
38.   
39.     }  
40.   
41. }  

import static org.junit.Assert.*;

import java.util.Map;

import org.junit.Test;

/**
 * 
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
public class DSACoderTest {

	@Test
	public void test() throws Exception {
		String inputStr = "abc";
		byte[] data = inputStr.getBytes();

		// 构建密钥
		Map<String, Object> keyMap = DSACoder.initKey();

		// 获得密钥
		String publicKey = DSACoder.getPublicKey(keyMap);
		String privateKey = DSACoder.getPrivateKey(keyMap);

		System.err.println("公钥:\r" + publicKey);
		System.err.println("私钥:\r" + privateKey);

		// 产生签名
		String sign = DSACoder.sign(data, privateKey);
		System.err.println("签名:\r" + sign);

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

	}

}

控制台输出：

Console代码  

1. 公钥:  
2. MIIBtzCCASwGByqGSM44BAEwggEfAoGBAP1/U4EddRIpUt9KnC7s5Of2EbdSPO9EAMMeP4C2USZp  
3. RV1AIlH7WT2NWPq/xfW6MPbLm1Vs14E7gB00b/JmYLdrmVClpJ+f6AR7ECLCT7up1/63xhv4O1fn  
4. xqimFQ8E+4P208UewwI1VBNaFpEy9nXzrith1yrv8iIDGZ3RSAHHAhUAl2BQjxUjC8yykrmCouuE  
5. C/BYHPUCgYEA9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCBgLRJ  
6. FnEj6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTxvqhRkImo  
7. g9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSoDgYQAAoGAIu4RUlcQLp49PI0MrbssOY+3uySVnp0TULSv  
8. 5T4VaHoKzsLHgGTrwOvsGA+V3yCNl2WDu3D84bSLF7liTWgOj+SMOEaPk4VyRTlLXZWGPsf1Mfd9  
9. 21XAbMeVyKDSHHVGbMjBScajf3bXooYQMlyoHiOt/WrCo+mv7efstMM0PGo=  
10.   
11. 私钥:  
12. MIIBTAIBADCCASwGByqGSM44BAEwggEfAoGBAP1/U4EddRIpUt9KnC7s5Of2EbdSPO9EAMMeP4C2  
13. USZpRV1AIlH7WT2NWPq/xfW6MPbLm1Vs14E7gB00b/JmYLdrmVClpJ+f6AR7ECLCT7up1/63xhv4  
14. O1fnxqimFQ8E+4P208UewwI1VBNaFpEy9nXzrith1yrv8iIDGZ3RSAHHAhUAl2BQjxUjC8yykrmC  
15. ouuEC/BYHPUCgYEA9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCB  
16. gLRJFnEj6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTxvqhR  
17. kImog9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSoEFwIVAIegLUtmm2oQKQJTOiLugHTSjl/q  
18.   
19. 签名:  
20. MC0CFQCMg0J/uZmF8GuRpr3TNq48w60nDwIUJCyYNah+HtbU6NcQfy8Ac6LeLQs=  
21.   
22. 状态:  
23. true  

公钥:
MIIBtzCCASwGByqGSM44BAEwggEfAoGBAP1/U4EddRIpUt9KnC7s5Of2EbdSPO9EAMMeP4C2USZp
RV1AIlH7WT2NWPq/xfW6MPbLm1Vs14E7gB00b/JmYLdrmVClpJ+f6AR7ECLCT7up1/63xhv4O1fn
xqimFQ8E+4P208UewwI1VBNaFpEy9nXzrith1yrv8iIDGZ3RSAHHAhUAl2BQjxUjC8yykrmCouuE
C/BYHPUCgYEA9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCBgLRJ
FnEj6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTxvqhRkImo
g9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSoDgYQAAoGAIu4RUlcQLp49PI0MrbssOY+3uySVnp0TULSv
5T4VaHoKzsLHgGTrwOvsGA+V3yCNl2WDu3D84bSLF7liTWgOj+SMOEaPk4VyRTlLXZWGPsf1Mfd9
21XAbMeVyKDSHHVGbMjBScajf3bXooYQMlyoHiOt/WrCo+mv7efstMM0PGo=

私钥:
MIIBTAIBADCCASwGByqGSM44BAEwggEfAoGBAP1/U4EddRIpUt9KnC7s5Of2EbdSPO9EAMMeP4C2
USZpRV1AIlH7WT2NWPq/xfW6MPbLm1Vs14E7gB00b/JmYLdrmVClpJ+f6AR7ECLCT7up1/63xhv4
O1fnxqimFQ8E+4P208UewwI1VBNaFpEy9nXzrith1yrv8iIDGZ3RSAHHAhUAl2BQjxUjC8yykrmC
ouuEC/BYHPUCgYEA9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCB
gLRJFnEj6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTxvqhR
kImog9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSoEFwIVAIegLUtmm2oQKQJTOiLugHTSjl/q

签名:
MC0CFQCMg0J/uZmF8GuRpr3TNq48w60nDwIUJCyYNah+HtbU6NcQfy8Ac6LeLQs=

状态:
true

注意状态为true，就验证成功！