JAVA加密算法（DSA）

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！也就是说传输中的数据可以不再加密，接收方获得数据后，拿到公钥与签名比对数据是否有效！ 

通过java代码实现如下：Coder类见 java加密技术（一） 
Java代码 

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.spec.PKCS8EncodedKeySpec;   
import java.security.spec.X509EncodedKeySpec;   
import java.util.HashMap;   
import java.util.Map;   
  
  
/**  
* DSA安全编码组件  
*   
*/  
public abstract class DSACoder extends Coder {   
    /**  
     * 可以使用DSA方式获得签名，也可以使用RSA方式获得签名，注意成对儿出现。  
     *   
     * <code>  
     * public static final String KEY_ALGORITHM = "RSA";  
     * public static final String SIGNATURE_ALGORITHM = "MD5withRSA";  
     * </code>  
     **/  
    public static final String KEY_ALGORITHM = "DSA";   
    public static final String SIGNATURE_ALGORITHM = "DSA";   
  
    /**  
     * 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(KEY_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(SIGNATURE_ALGORITHM);   
        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);   
  
        // KEY_ALGORITHM 指定的加密算法   
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);   
  
        // 取公钥匙对象   
        PublicKey pubKey = keyFactory.generatePublic(keySpec);   
  
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);   
        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(KEY_ALGORITHM);   
        // 初始化随机产生器   
        SecureRandom secureRandom = new SecureRandom();   
        secureRandom.setSeed(seed.getBytes());   
        keygen.initialize(1024, secureRandom);   
  
        KeyPair keys = keygen.genKeyPair();   
  
        PublicKey publicKey = keys.getPublic();   
        PrivateKey privateKey = 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());   
    }   
}  

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.spec.PKCS8EncodedKeySpec; 
import java.security.spec.X509EncodedKeySpec; 
import java.util.HashMap; 
import java.util.Map; 


/** 
* DSA安全编码组件 
* 
*/ 
public abstract class DSACoder extends Coder { 
/** 
* 可以使用DSA方式获得签名，也可以使用RSA方式获得签名，注意成对儿出现。 
* 
* <code> 
* public static final String KEY_ALGORITHM = "RSA"; 
* public static final String SIGNATURE_ALGORITHM = "MD5withRSA"; 
* </code> 
**/ 
public static final String KEY_ALGORITHM = "DSA"; 
public static final String SIGNATURE_ALGORITHM = "DSA"; 

/** 
* 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(KEY_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(SIGNATURE_ALGORITHM); 
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); 

// KEY_ALGORITHM 指定的加密算法 
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); 

// 取公钥匙对象 
PublicKey pubKey = keyFactory.generatePublic(keySpec); 

Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM); 
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(KEY_ALGORITHM); 
// 初始化随机产生器 
SecureRandom secureRandom = new SecureRandom(); 
secureRandom.setSeed(seed.getBytes()); 
keygen.initialize(1024, secureRandom); 

KeyPair keys = keygen.genKeyPair(); 

PublicKey publicKey = keys.getPublic(); 
PrivateKey privateKey = 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()); 
} 
} 


不仅可以使用DSA算法，同样也可以使用RSA算法做数字签名，但要注意成对出现： 
public static final String KEY_ALGORITHM = "RSA"; 
public static final String SIGNATURE_ALGORITHM = "MD5withRSA"; 

再给出一个测试类： 
Java代码 
import static org.junit.Assert.*;   
  
import java.util.Map;   
  
import org.junit.Test;   
  
/**  
*   
*/  
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);   
  
    }   
  
}  

import static org.junit.Assert.*; 

import java.util.Map; 

import org.junit.Test; 

/** 
* 
*/ 
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 
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  

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