Java中对称密钥、非对称密钥和数字签名的用法

1、非对称密钥：

 

package com.mysec;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import static com.mysec.myutil.Util.println;
public class MDTest {

/**
 * @param args
 */
public static void main(String[] args) {
// TODO Auto-generated method stub

try {
byte[] pw1 = new String("dkfdsfsdflasdfasdfasdf").getBytes();
byte[] pw2 = new String("dkfdsfsdflasdfasdfasdf").getBytes();
//MD2/MD5/SHA1
//非对称密钥
MessageDigest md = MessageDigest.getInstance("MD5");
System.out.println("服务提供者："+md.getProvider());
byte[] b1 = new String("这是散列字节").getBytes();

md.update(b1);
byte[] r1 = md.digest(pw1);

md.update(b1);
byte[] r2 = md.digest(pw2);

println("pw1加密后："+new String(r1));
println("pw2加密后："+new String(r2));
//转换为16进制方便读取放入数据库
println(convertHex(r1));
println(convertHex(r2));
println(md.isEqual(r1, r2));

//println(md.getAlgorithm());
//println(md.getDigestLength());

} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static String convertHex(byte[] b){
StringBuffer sb = new StringBuffer();
for(byte tmp:b){
sb.append(Integer.toHexString(tmp&0XFF));
}
return sb.toString();
}

}

 

 2、对称密钥算法

 

package com.mysec;
import static com.mysec.myutil.Util.println;

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
public class CipherTest {

/**
 * @param args
 * @throws NoSuchPaddingException 
 * @throws NoSuchAlgorithmException 
 */
public static byte[] encoder(Key key,String text){
return null;
}
public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
// TODO Auto-generated method stub
//对称算法名  
String info = "this is a my info!";
KeyGenerator generator = KeyGenerator.getInstance("DES");
//初始化长度，DES只能是56
generator.init(56);
//生成密钥
Key key = generator.generateKey();
byte[] keyEncode = key.getEncoded();
println("密钥是："+toHexString(keyEncode));

Cipher cipher  = Cipher.getInstance("DES/ECB/PKCS5Padding");
println(cipher.getProvider().getName());

println("原文："+info);
//用cipher进行加密
cipher.init(Cipher.ENCRYPT_MODE,key);
byte[] encoderResult = cipher.doFinal(info.getBytes());
println("密文:"+toHexString(encoderResult));

//用cipher进行解密
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] decryptResult = cipher.doFinal(encoderResult);
println("解密后:"+new String(decryptResult));
}

public static String toHexString(byte[] b){
StringBuffer sb = new StringBuffer();
for(int i=0;i<b.length;i++){
sb.append(Integer.toHexString(b[i]&0XFF));
}
return sb.toString();
}

}

 

 3、数字签名

package com.mysec;

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import static com.mysec.myutil.Util.println;
public class SignTest {

/**
 * @param args
 */
public static void main(String[] args) throws Exception{
// TODO Auto-generated method stub
String info = "this is my info!";

//获得密钥对
KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
//初始化长度
generator.initialize(1024);
//生成密钥对
KeyPair keyPair = generator.generateKeyPair();
//获得私钥
PrivateKey privateKey = keyPair.getPrivate();
println("私钥是："+toHexString(privateKey.getEncoded()));
//获得公钥
PublicKey publicKey = keyPair.getPublic();
println("公钥是："+toHexString(publicKey.getEncoded()));


Signature sign = Signature.getInstance("MD5WithRSA");
//对私钥进行签名
sign.initSign(privateKey);
sign.update(info.getBytes());
//获得签名值
byte[] signature = sign.sign();
println("签名值是:"+toHexString(signature));

//用公钥初始化签名对象
sign.initVerify(publicKey);
//这里应该是解密后的信息，这里直接用原来的
sign.update(info.getBytes());

//签证签名
if(sign.verify(signature)){
System.out.println("验证签名成功！");
}else{
System.out.println("验证签名失败！");

}
}

public static String toHexString(byte[] b){
StringBuffer sb = new StringBuffer();
for(int i=0;i<b.length;i++){
sb.append(Integer.toHexString(b[i]&0XFF));
}
return sb.toString();
}

}