Java实现RSR对文件加密

说明bcprov-ext-jdk16-141.jar包在 http://www.bouncycastle.org/ 上下载

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*/

package rsa;

import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
*
* @author Administrator
*/
public class GenKey {
public static void main(String[] args){//创建密钥
try {
//创建密钥对生成器
KeyPairGenerator KPG = KeyPairGenerator.getInstance("RSA");
//初始化密钥生成器
KPG.initialize(1024);
//生成密钥对
KeyPair KP=KPG.genKeyPair();
//获取公钥和密钥
PublicKey pbKey=KP.getPublic();
PrivateKey prKey=KP.getPrivate();
//保存公钥到文件
FileOutputStream out=new FileOutputStream("RSAPublic.dat");
ObjectOutputStream fileOut=new ObjectOutputStream(out);
fileOut.writeObject(pbKey);
//保存密钥到文件
FileOutputStream outPrivate=new FileOutputStream("RSAPrivate.dat");
ObjectOutputStream privateOut=new ObjectOutputStream(outPrivate);
privateOut.writeObject(prKey);
} catch (Exception ex) {
Logger.getLogger(GenKey.class.getName()).log(Level.SEVERE, null, ex);
}

}

}

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package rsatest;

import cipherinputstream.EncryptAndDecrypt;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.security.Key;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.crypto.Cipher;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

/**
*
* @author Administrator
*/
public class RRSSA {

public static void main(String[] args) {
//要用作加密或解密的文件名
String dataFileName = args[0];
//是区分是加密还是解密，加密为encrypt,解密为decrypt
String opMode = args[1];
String keyFileName = null;
//密钥存放的文件名
if (opMode.equalsIgnoreCase("encrypt")) {
keyFileName = "RSAPublic.dat";
} else {
keyFileName = "RSAPrivate.dat";
}

try {
//生成密钥
FileInputStream keyFIS = new FileInputStream(keyFileName);
ObjectInputStream OIS = new ObjectInputStream(keyFIS);
Key key = (Key) OIS.readObject();

//创建并初始化密码器
Cipher cp = Cipher.getInstance("RSA", new BouncyCastleProvider());//此处不能少
//BouncyCastLeProvider类在bcprov-ext-jdk16-141.jar中
if (opMode.equalsIgnoreCase("encrypt")) {

cp.init(Cipher.ENCRYPT_MODE, key);
} else if (opMode.equalsIgnoreCase("decrypt")) {
cp.init(Cipher.DECRYPT_MODE, key);
} else {
return;
}

FileInputStream dataFIS = new FileInputStream(dataFileName);
//取得要加密的数据
int size = dataFIS.available();
byte[] encryptByte = new byte[size];
dataFIS.read(encryptByte);

//如果是加密操作
if (opMode.equalsIgnoreCase("encrypt")) {
//建立文件输出流
FileOutputStream FOS = new FileOutputStream("mi.txt");
//RSA算法必须采用分块加密
//取得RSA加密的块的大小
int blockSize = cp.getBlockSize();
//根据给定的输入长度 inputLen（以字节为单位），返回保存下一个 update 或 doFinal 操作结果所需的输出缓冲区长度（以字节为单位）。
int outputBlockSize = cp.getOutputSize(encryptByte.length);

//确定要加密的次数(加密块的个数)
int leavedSize = encryptByte.length % blockSize;
int blocksNum = leavedSize == 0 ? encryptByte.length / blockSize
: encryptByte.length / blockSize + 1;

byte[] cipherData = new byte[blocksNum * outputBlockSize];

//对每块数据分别加密
for (int i = 0; i < blocksNum; i++) {

if ((encryptByte.length - i * blockSize) > blockSize) {
cp.doFinal(encryptByte, i * blockSize, blockSize, cipherData, i * outputBlockSize);
} else {
cp.doFinal(encryptByte, i * blockSize, encryptByte.length - i * blockSize, cipherData, i * outputBlockSize);
}

}

FOS.write(cipherData);

FOS.close();

} else {//如果是解密操作

FileOutputStream FOS = new FileOutputStream("jiemi.txt");
int blockSize = cp.getBlockSize();
int j = 0;

//分别对各块数据进行解密
while ((encryptByte.length - j * blockSize) > 0) {
FOS.write(cp.doFinal(encryptByte, j * blockSize, blockSize));
j++;
}

FOS.close();

}
} catch (Exception ex) {
Logger.getLogger(EncryptAndDecrypt.class.getName()).log(Level.SEVERE, null, ex);
}
}
}