Java安全之数字签名

.security;

import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

public class SignatureTest {
private static final String KEY_PAIR_ALGOGRITHM = "DSA";
private static final String SIGNATURE_ALGOGRITHM = "SHA1withDSA";
private static final String PUBLIC_KEY_PATH = "public.key";
private static final String PRIVATE_KEY_PATH = "private.key";
private static final String SIGNATURE_PATH = "signature.dat";

@Test //生成公钥与私钥并保存至文件
public void testGenerateKeyPair() throws Exception {
KeyPairGenerator generator = KeyPairGenerator.getInstance(KEY_PAIR_ALGOGRITHM);
KeyPair keyPair = generator.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();

writeKey(PUBLIC_KEY_PATH, publicKey);
writeKey(PRIVATE_KEY_PATH, privateKey);
}

@Test
public void testSign() throws Exception {
String myInfo = "《Java》精讲公从号";
PrivateKey privateKey = PrivateKey.class.cast(readKey(PRIVATE_KEY_PATH));
//初始化一个Signature对象，并用私钥对信息签名，JDK(7)支持的数字签名算法有很多，
//具体可参见http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Signature
Signature signature = Signature.getInstance(SIGNATURE_ALGOGRITHM);
//私钥签名
signature.initSign(privateKey);
//更新待签名数据
signature.update(myInfo.getBytes());
//得到数字签名
byte[] signed = signature.sign();

//把信息和签名保存在一个文件中
writeObjects(SIGNATURE_PATH, myInfo, signed);
}

@Test
public void testVerify() throws Exception {
PublicKey publicKey = PublicKey.class.cast(readKey(PUBLIC_KEY_PATH));

List

//初始化签名引擎类
Signature signature = Signature.getInstance(SIGNATURE_ALGOGRITHM);
//公钥用于验证签名
signature.initVerify(publicKey);
//更新待待签名验证数据
signature.update(info.getBytes());
//测试签名是否正确
System.out.println(signature.verify(signed) ? "签名正确" : "签名错误");
}
public void writeKey(String path, Key key) throws Exception {
FileOutputStream fos = new FileOutputStream(path);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(key);
oos.close();
}

public Key readKey(String path) throws Exception {
FileInputStream fis = new FileInputStream(path);
ObjectInputStream bis = new ObjectInputStream(fis);
Object object = bis.readObject();
bis.close();
return (Key) object;
}

public void writeObjects(String path, Serializable... objects) throws Exception {
if(objects!=null) {
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(path));
for(Serializable object : objects) {
oos.writeObject(object);
}
oos.close();
}
}

public List

boolean flag = true;
while(flag) {
try {
objects.add(ois.readObject());
} catch (EOFException e) {
//表示流中已无对象可读
break;
}
}
ois.close();
return objects;
}

}