JAVA加密算法6

关键字: dsa, 公钥, 私钥, 数字签名, 非对称加密
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！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
*
* @author 梁栋
* @version 1.0
* @since 1.0
*/
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。
*
*
* public static final String KEY_ALGORITHM = "RSA";
* public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
*
**/
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 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 map = new HashMap(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 initKey() throws Exception {
return initKey(DEFAULT_SEED);
}

/**
* 取得私钥
*
* @param keyMap
* @return
* @throws Exception
*/
public static String getPrivateKey(Map 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 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
*
* @author 梁栋
* @version 1.0
* @since 1.0
*/
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。
*
*
* public static final String KEY_ALGORITHM = "RSA";
* public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
*
**/
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 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 map = new HashMap(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 initKey() throws Exception {
return initKey(DEFAULT_SEED);
}

/**
* 取得私钥
*
* @param keyMap
* @return
* @throws Exception
*/
public static String getPrivateKey(Map 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 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;

/**
*
* @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 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;

/**
*
* @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 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


注意状态为true，就验证成功！