aes.java

密码学中RSA,AES和数值签名的实现。。。。

import java.io.*;
import java.security.*;
import javax.crypto.*;
import com.sun.crypto.provider.SunJCE;
import java.math.BigInteger;

public class AES
{
 public final static String filename = "secret.key";
 /*
 生成密匙
 */
 public static void createKey() {
	 try
	 {
	 KeyGenerator keygen = KeyGenerator.getInstance("AES");
	 SecureRandom random = new SecureRandom();
	 keygen.init(random);
	 SecretKey key = keygen.generateKey();
	 byte[] t = key.getEncoded();
	 BigInteger tem = new BigInteger(t);
	 System.out.println("密匙："+tem);
     writeKey(key);
	 }
	 catch (Exception e)
	 {
		 e.printStackTrace();
	 }

 }

 /*
 加密
 */
 public static boolean Encrypt(String mingpath, String mipath) {
      try
      {
		FileInputStream fin = new FileInputStream(mingpath);
		FileOutputStream fout = new FileOutputStream(mipath);
		Cipher cipher = Cipher.getInstance("AES");
		Key key = (Key)getKey();
		if(key==null){
			System.out.println("请先生成密匙！！");
			return false;
		}
		cipher.init(Cipher.ENCRYPT_MODE,key);
		crypt(fin,fout,cipher,true);
		fin.close();
		fout.close();
		return true;
      }
      catch (Exception e)
      {
		//  e.printStackTrace();
		  System.out.println("待加密的ming.txt无法找到请确认其存在！");
		  return false;
      }  
 }

  /*
解密
 */
 public static boolean Decrypt(String mipath, String demingpath) {
      try
      {
		FileInputStream fin = new FileInputStream(mipath);
		FileOutputStream fout = new FileOutputStream(demingpath);
		Cipher cipher = Cipher.getInstance("AES");
		Key key = (Key)getKey();
		if(key==null) {
			System.out.println("请先生成密匙！！");
			return false;
		}
		cipher.init(Cipher.DECRYPT_MODE,key);
		crypt(fin,fout,cipher,false);
		fin.close();
		fout.close();
		return true;
      }
      catch (Exception e)
      {
		//  e.printStackTrace();
		System.out.println("待解密的mi.txt无法找到请确认其存在！");
        return false;
	}  
 }

 public static void crypt(InputStream in, OutputStream out, Cipher cipher,boolean flag) {
	 try
	 {
  int blockSize = cipher.getBlockSize();
  int outputSize = cipher.getOutputSize(blockSize);
  byte[] inBytes = new byte[blockSize];
  byte[] outBytes = new byte[outputSize];
  
  int inLength = 0;
  boolean more = true;
  if(flag) System.out.print("密文的char值：");
  while(more){
   inLength = in.read(inBytes);
   if(inLength == blockSize){
    int outLength = cipher.update(inBytes, 0,blockSize,outBytes);
    out.write(outBytes,0,outLength);
	if(flag) {
	for(int i=0;i<outLength;i++)
	System.out.print(outBytes[i]);
   }
   }
   else more = false;
  }
  if(inLength > 0){
   outBytes = cipher.doFinal(inBytes,0,inLength);
  }
  else{
   outBytes = cipher.doFinal();
  }
   if(flag){
	   for(int i=0;i<outBytes.length;i++)
		  System.out.print(outBytes[i]);
	   System.out.print("\n");

   }
  out.write(outBytes);
	 }
	 catch (Exception e)
	 {
		 e.printStackTrace();
	 }
 }
/**
 * 将密匙作为对象写入文件
 * @param obj
 */
private static void writeKey(Object obj) {
	File file = new File(filename);
	try {
		FileOutputStream out = new FileOutputStream(file);
		ObjectOutputStream objout = new ObjectOutputStream(out);
	    objout.writeObject(obj);
	    out.close();
	    objout.close(); 
	} catch (FileNotFoundException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	} catch (IOException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
}
/*
从文件中取出密匙
*/
public static Object getKey() {
	File file = new File(filename);
	Security.addProvider(new SunJCE());
	try {
		FileInputStream fin = new FileInputStream(file);
		ObjectInputStream oin = new ObjectInputStream(fin);
		Object obj = oin.readObject();
		return obj;
	} catch (FileNotFoundException e) {
		// TODO Auto-generated catch block
	} catch (IOException e) {
		// TODO Auto-generated catch block
	} catch (ClassNotFoundException e) {
		// TODO Auto-generated catch block
	}
	return null;
}
/*
从文件中读取字符串
*/
public static String getString(String path) {
	File file = new File(path);
	StringBuffer buffer = new StringBuffer();
	byte[] bytes = new byte[1024];
	int i = 0;
	try
	{
		FileInputStream fin = new FileInputStream(file);
		
		while((i=fin.read(bytes))>0) {
           buffer.append(new String(bytes,0,i));
		}

		fin.close();
	}
	catch (Exception e)
	{
		e.printStackTrace();
	}
	return buffer.toString();
}

/*
将字符串写入文件中
*/
public static void storeString(String str, String path) {
   File file = new File(path);
   try
   {
	 FileOutputStream fout = new FileOutputStream(file);
	 fout.write(str.getBytes());
	 fout.close();
   }
   catch (Exception e)
   {
	 e.printStackTrace();
   }
}

public static void main(String[] args) {
	String in = null;
	BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
	System.out.println("可选输入:");
	System.out.println("1:生成密匙。2:加密。3:解密。4:退出。");
	try
	{
		while(true){
			in = read.readLine();
		   if(in.equals("1")){
			System.out.println("生成密匙中.....");
            createKey();
			System.out.println("密匙已经生成！");
		   }else if(in.equals("2")){
			System.out.println("加密文件中.....");
            boolean f = Encrypt("ming.txt","mi.txt");
			if(f){
		    System.out.println("加密成功！");
			}
		   } else if(in.equals("3")){
			System.out.println("解密文件中......");
          boolean f= Decrypt("mi.txt","deming.txt");
		  if(f){
		   System.out.println("解密成功！明文在文件deming.txt中");
		  }
		   } else if(in.equals("4")){
			   System.out.println("Byte Byte!");
			   break;
		   } else{
			   System.out.println("输入有误，请按提示键操作!");
		   }
		}
	}
	catch (Exception e)
	{
		e.printStackTrace();
		System.out.println("抱歉，发生异常了！");
		return ;
	}
}
}