/*
* ABchatRSA.java
*
* Created on 2008年6月28日, 下午12:38
*在苦苦寻找答案为什么会抛出 javax.crypto.BadPaddingException: Data must start with zero
*异常后我决定将正确的答案写出来供大家参考
*大连理工大学 软件学院 郭晓鹤
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*/
package abchat.org.security;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
/**
*
* @author GuoXiaoHe
*/
public class ABchatRSA {
/** Creates a new instance of ABchatRSA */
/*构建需要的函数变量*/
private KeyPairGenerator kePaGen=null; //秘密钥匙生成器;
private KeyPair keyPair=null; //钥匙对，公尺 和米尺；
private PublicKey publicKey=null; //共匙；
private PrivateKey privateKey=null; //密匙；
private int keySize =512; //密匙长
public ABchatRSA(int keysize) {
this.keySize= keysize;
try{
this.kePaGen= KeyPairGenerator.getInstance("RSA"); //
this.kePaGen.initialize(this.keySize);
//
this.keyPair=this.kePaGen.genKeyPair();
this.privateKey=this.keyPair.getPrivate();
this.publicKey=this.keyPair.getPublic();
//this.abcharRsaCipher=Cipher.getInstance("RSA/ECB/PKCS1Padding");
}catch( Exception err){
err.printStackTrace();
}
}
public PublicKey getPublicKey()
{
return this.publicKey;
}
public PrivateKey getPrivateKey()
{
return this.privateKey;
}
public static String encripyRSA(String platxt,PublicKey publickey)
{
String cipherStr=null; //返回的加密后的字符串;
byte[]plainByte=null; //获得明文的byte数组;
byte[]cipherByte; //产生秘闻的byte数组;
Cipher cipher =null;
try{
plainByte=platxt.getBytes("ISO-8859-1");
cipher=Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE,publickey);
cipherByte=cipher.doFinal(plainByte);
cipherStr=new String(cipherByte,"ISO-8859-1");
}catch(Exception err){
err.printStackTrace();
System.out.println("error in en: "+err.toString());
}
return cipherStr;
}
public static String decripyRSA(String cphtxt,PrivateKey privateKey)
{
byte[] cipherByte =null; //获得秘闻的byte数组;
byte[] plainByte =null; //解密后的明文数组;
String plainStr =null; //解密后的明文数组;
Cipher cipher =null; //加密用;
try{
cipherByte =cphtxt.getBytes("ISO-8859-1"); //统一使用该种编码方式;
cipher =Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE,privateKey);
plainByte=cipher.doFinal(cipherByte);
plainStr=new String(plainByte,"ISO-8859-1");
}catch(Exception err)
{
err.printStackTrace();
}
return plainStr;
}
public static void main(String []args)
{
ABchatRSA arsa=new ABchatRSA(512);
String en=ABchatRSA.encripyRSA("HELLO world",arsa.getPublicKey());
String de=ABchatRSA.decripyRSA(en,arsa.getPrivateKey());
System.out.println(de);
}
}