java RSA生成明文公钥私钥，对文件进行加密解密

java RSA生成明文公钥私钥，对文件进行加密解密

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.math.BigInteger;
import java.security.GeneralSecurityException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class Test {
	//RSA算法对文件加密
	public void encryptByRSA(String fileName, String saveFileName, String keyFileName) throws Exception {
		long start = System.currentTimeMillis();
		try {
			KeyGenerator keygen = KeyGenerator.getInstance("AES");
			SecureRandom random = new SecureRandom();
			keygen.init(random);
			SecretKey key = keygen.generateKey();
			String[] result = readKeyUtil(new File(keyFileName));
			RSAPublicKey key2 = getPublicKey(result[0],result[1]);
			Cipher cipher = Cipher.getInstance("RSA");
			cipher.init(Cipher.WRAP_MODE, key2);
			byte[] wrappedKey = cipher.wrap(key);
			DataOutputStream out = new DataOutputStream(new FileOutputStream(saveFileName));
			out.writeInt(wrappedKey.length);
			out.write(wrappedKey);
			InputStream in = new FileInputStream(fileName);
			cipher = Cipher.getInstance("AES");
			cipher.init(Cipher.ENCRYPT_MODE, key);
			crypt(in, out, cipher);
			in.close();
			out.close();
		} catch (GeneralSecurityException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		long end = System.currentTimeMillis();
		System.out.println("总共耗时："+(end-start));
	}
	//RSA算法对文件解密
	public void decryptByRSA(String fileName, String saveFileName, String keyFileName) throws Exception {
		try {
			DataInputStream in = new DataInputStream(new FileInputStream(fileName));
			int length = in.readInt();
			byte[] wrappedKey = new byte[length];
			in.read(wrappedKey, 0, length);
			String[] result = readKeyUtil(new File(keyFileName));
			RSAPrivateKey key2 = getPrivateKey(result[0],result[1]);
		
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.UNWRAP_MODE, key2);
		Key key = cipher.unwrap(wrappedKey, "AES", Cipher.SECRET_KEY);
		
		OutputStream out = new FileOutputStream(saveFileName);
		cipher = Cipher.getInstance("AES");
		cipher.init(Cipher.DECRYPT_MODE, key);
		
		crypt(in, out, cipher);
		in.close();
		out.close();
	} catch (GeneralSecurityException e) {
		e.printStackTrace();
	} catch (IOException e) {
		e.printStackTrace();
	}
}

//对数据块加密
public void crypt(InputStream in, OutputStream out, Cipher cipher) throws IOException, GeneralSecurityException {
	int blockSize = cipher.getBlockSize();
	int outputSize = cipher.getOutputSize(blockSize);
	byte[] inBytes = new byte[blockSize];
	byte[] outBytes = new byte[outputSize];
	
	int inLength = 0;
	boolean next = true;
	while (next) {
		inLength = in.read(inBytes);
		System.out.println(inLength);
		if (inLength == blockSize) {
			int outLength = cipher.update(inBytes, 0, blockSize, outBytes);
			out.write(outBytes, 0, outLength);
		} else {
			next = false;
		}
	}
	if (inLength > 0) {
		outBytes = cipher.doFinal(inBytes, 0, inLength);
	} else {
		outBytes = cipher.doFinal();
	}
	out.write(outBytes);
}

//生成RSA密钥对
public void generateRSAKey(String savePath) throws Exception {
	try {
		KeyPairGenerator keygen = KeyPairGenerator.getInstance("RSA");
		SecureRandom random = new SecureRandom();
		keygen.initialize(RSA_KEYSIZE, random);
		KeyPair keyPair = keygen.generateKeyPair();
		RSAPublicKey puk=(RSAPublicKey) keyPair.getPublic();
		createXmlFile(puk.getModulus().toString(), puk.getPublicExponent().toString(),savePath + "\\public.xml");
		RSAPrivateKey prk=(RSAPrivateKey) keyPair.getPrivate();
		createXmlFile(prk.getModulus().toString(), prk.getPrivateExponent().toString(),savePath + "\\private.xml");
		/*OutputStreamWriter osw  = new OutputStreamWriter(new FileOutputStream(savePath + "\\public.xml"));
		// 得到公钥字符串 
		System.out.println(puk.getModulus());
		System.out.println(puk.getPublicExponent());
		System.out.println(prk.getModulus());
		System.out.println(prk.getPrivateExponent());
        // 得到私钥字符串 
		osw.write(createXmlFile(puk.getModulus().toString(), puk.getPublicExponent().toString()));
		osw.close();
		osw = new OutputStreamWriter(new FileOutputStream(savePath + "\\private.xml"));
		osw.write(createXmlFile(prk.getModulus().toString(), prk.getPrivateExponent().toString()));
		osw.close();*/
	} catch (NoSuchAlgorithmException e) {
		e.printStackTrace();
	}
}

   /**
  * 使用模和指数生成RSA公钥
  * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
  * /None/NoPadding】
  * 
  * @param modulus
  *            模
  * @param exponent
  *            指数
  * @return
  */
 public static RSAPublicKey getPublicKey(String modulus, String exponent) {
     try {
         BigInteger b1 = new BigInteger(modulus);
         BigInteger b2 = new BigInteger(exponent);
         KeyFactory keyFactory = KeyFactory.getInstance("RSA");
         RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
         return (RSAPublicKey) keyFactory.generatePublic(keySpec);
     } catch (Exception e) {
         e.printStackTrace();
         return null;
     }
 }

 /**
  * 使用模和指数生成RSA私钥
  * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
  * /None/NoPadding】
  * 
  * @param modulus
  *            模
  * @param exponent
  *            指数
  * @return
  */
 public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {
     try {
         BigInteger b1 = new BigInteger(modulus);
         BigInteger b2 = new BigInteger(exponent);
         KeyFactory keyFactory = KeyFactory.getInstance("RSA");
         RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);
         return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
     } catch (Exception e) {
         e.printStackTrace();
         return null;
     }
 }

/**
 * 生成xml字符串
 * @return
 * @throws Exception 
 */
public static void createXmlFile(String Modulus,String Exponent,String filepath) throws Exception{
	 Document document = DocumentHelper.createDocument();
     Element root = document.addElement( "root" );
     Element supercarElement= root.addElement("Modulus");

     supercarElement.addText(Modulus);
     Element supercarElement2= root.addElement("Exponent");

     supercarElement2.addText(Exponent);
     // 写入到一个新的文件中 
     writer(document,filepath);
}
/** 
 * 把document对象写入新的文件 
 *  
 * @param document 
 * @throws Exception 
 */  
public static void writer(Document document,String path) throws Exception {  
    // 紧凑的格式  
    // 排版缩进的格式  
    OutputFormat format = OutputFormat.createPrettyPrint();  
    // 设置编码  
    format.setEncoding("UTF-8");  
    // 创建XMLWriter对象,指定了写出文件及编码格式  
    XMLWriter writer = new XMLWriter(new OutputStreamWriter(  
            new FileOutputStream(new File(path)), "UTF-8"), format);  
    // 写入  
    writer.write(document);  
    // 立即写入  
    writer.flush();  
    // 关闭操作  
    writer.close();  
}

public String[] readKeyUtil(File file) throws DocumentException{
	 // 创建saxReader对象  
    SAXReader reader = new SAXReader();  
    // 通过read方法读取一个文件 转换成Document对象  
    Document document = reader.read(file);  
    //获取根节点元素对象  
    Element node = document.getRootElement();  
    Element ele = node.element("Modulus");
    String Modulus = ele.getTextTrim();
    Element ele1 = node.element("Exponent");
    String Exponent = ele1.getTextTrim();
	return new String[]{Modulus,Exponent};
}

private static final int RSA_KEYSIZE = 1024;
public static void main(String[] args) throws Exception {
	//生成xml格式的公钥和私钥
	new Test().generateRSAKey("C://ZJY//1//");
	//对文件进行加密
	new Test().encryptByRSA("C://ZJY//12345.txt", "C://ZJY//123456.txt", "C:/ZJY/1/public.xml");
	//对文件进行解密
	new Test().decryptByRSA("C://ZJY//123456.txt", "C://ZJY//1234567.txt", "C:/ZJY/1/private.xml");
	
}

}