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！
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.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;
public abstract class DSACoder
extends Coder {
public static final String ALGORITHM =
"DSA";
private static final int KEY_SIZE =
1024;
private static final String DEFAULT_SEED =
"0f22507a10bbddd07d8a3082122966e3";
private static final String PUBLIC_KEY =
"DSAPublicKey";
private static final String PRIVATE_KEY =
"DSAPrivateKey";
public static String sign(
byte[] data, String privateKey)
throws Exception {
byte[] keyBytes = decryptBASE64(privateKey); PKCS8EncodedKeySpec pkcs8KeySpec =
new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM); PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec); Signature signature = Signature.getInstance(keyFactory.getAlgorithm()); signature.initSign(priKey); signature.update(data);
return encryptBASE64(signature.sign()); }
public static boolean verify(
byte[] data, String publicKey, String sign)
throws Exception {
byte[] keyBytes = decryptBASE64(publicKey); X509EncodedKeySpec keySpec =
new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM); PublicKey pubKey = keyFactory.generatePublic(keySpec); Signature signature = Signature.getInstance(keyFactory.getAlgorithm()); signature.initVerify(pubKey); signature.update(data);
return signature.verify(decryptBASE64(sign)); }
public static Map<String, Object> initKey(String seed)
throws Exception { KeyPairGenerator keygen = KeyPairGenerator.getInstance(ALGORITHM); 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; }
public static Map<String, Object> initKey()
throws Exception {
return initKey(DEFAULT_SEED); }
public static String getPrivateKey(Map<String, Object> keyMap)
throws Exception { Key key = (Key) keyMap.get(PRIVATE_KEY);
return encryptBASE64(key.getEncoded()); }
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.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
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(); Map<String, Object> keyMap = DSACoder.initKey(); String publicKey = DSACoder.getPublicKey(keyMap); String privateKey = DSACoder.getPrivateKey(keyMap); System.err.println(
"公钥:\r" + publicKey); System.err.println(
"私钥:\r" + privateKey); String sign = DSACoder.sign(data, privateKey); System.err.println(
"签名:\r" + sign);
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<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
注意状态为true，就验证成功！
