Java加密技术之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
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！

通过java代码实现如下：

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  http://www.bt285.cn http://www.5a520.cn   
*     
* @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：

import static org.junit.Assert.*;      
     
import java.util.Map;      
     
import org.junit.Test;      
     
/** *//**    
*     
* @author 梁栋  http://www.5a520.cn  http://www.feng123.com  
* @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：

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