Android Open Source - AndroidCloud File D Encryption

• Back to Security/application  ↑

From Project

Back to project page AndroidCloud.

License

The source code is released under:

GNU General Public License

Java Source Code

package com.twlkyao.utils;
/*ww  w .j av a  2  s .c om*/
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import android.util.Log;

/**
 * File encryption and decryption.
 * @author Shiyao Qi
 * @date 2013.12.16
 * @email qishiyao2008@126.com
 */
/**
 * Implement the file encryption/decryption method.
 */
public class FileDEncryption {
  
     /*
        * ???????????????? 
        * @param keyStr ?????
        * @return 
        * @throws UnsupportedEncodingException
        */
  /**
   * Generate the byte array according to the string for TripleDES.
   * @param keyStr The string.
   * @return The generated byte array.
   * @throws UnsupportedEncodingException
   */
  public static byte[] build3DesKey(String keyStr) throws UnsupportedEncodingException{
    byte[] key = new byte[24];    //????24????????????????0
    byte[] temp = keyStr.getBytes("UTF-8");    //???????????
    
    /*
     * ???????
     * System.arraycopy(??????????????????????????????)
     */
    if(key.length > temp.length){
      //??temp???24???????temp??????????key???
      System.arraycopy(temp, 0, key, 0, temp.length);
    }else{
      //??temp??24???????temp??24???????key???
      System.arraycopy(temp, 0, key, 0, key.length);
    }
    return key;
  }
  
  /**
   * Use Algorithm:algorithm and Key:encKey to encrypt
   * the file:srcFilepath and store it in destFilepath.
   * @param srcFilepath The file path of the file to be encrypted.
   * @param algorithm The algorithm to be used.
   * @param encKey The encrypt key to be used.
   * @param destFilepath The file path to save the encrypted file.
   * @return True, if the encryption succeeds.
   */
  public boolean Encryption (String srcFilepath, String algorithm, String encKey, String destFilepath) {
    
    boolean flag = true;
    SecretKey enkey;
    try {
      enkey = new SecretKeySpec(build3DesKey(encKey), algorithm);
      Cipher cipher = Cipher.getInstance(algorithm); // Creates a new Cipher for the specified algorithm.
      cipher.init(Cipher.ENCRYPT_MODE, enkey); // Initial to ENCRYTP_MODE
      
      InputStream is = new FileInputStream(srcFilepath);
      
      File destFile = new File(destFilepath); // Create a new File instance.
      if(!destFile.exists()) { // Only create a new file, if the file does not exists.
        try {
          destFile.createNewFile(); // Create a new, empty file.
        } catch (IOException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
//          return false;
        }
      }
      

      OutputStream out = new FileOutputStream(destFile);
      CipherInputStream cis = new CipherInputStream(is, cipher);
      byte[] buffer = new byte[1024];
      int r;
      while ((r = cis.read(buffer)) > 0) {
        out.write(buffer, 0, r);
      }
      cis.close();
      is.close();
      out.close();
    } catch (UnsupportedEncodingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (NoSuchAlgorithmException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (NoSuchPaddingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (InvalidKeyException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block
//      e.printStackTrace();
      Log.e("FileNotFound", e.toString());
      flag = false;
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    }
    
    return flag;
  }
  
  /**
   * Use Algorithm:algorithm and Key:encKey to decrypt
   * the file:srcFilepath and store it in destFilepath.
   * @param srcFilepath The file path of the file to be decrypted.
   * @param algorithm The algorithm to be used.
   * @param encKey The encrypt key to be used.
   * @param destFilepath The file path to save the decrypted file.
   * @return The decrypt status.
   */
  public boolean Decryption(String srcFilepath, String algorithm, String decKey, String destFilepath) {
    
    boolean flag = true;
    SecretKey deskey;
    try {
      deskey = new SecretKeySpec(build3DesKey(decKey), algorithm);
      Cipher cipher = Cipher.getInstance(algorithm); // Creates a new Cipher for the specified algorithm.
      cipher.init(Cipher.DECRYPT_MODE, deskey); // Initial to ENCRYTP_MODE
      InputStream is = new FileInputStream(srcFilepath);
      File destFile = new File(destFilepath);

      if(!destFile.exists()){
        destFile.createNewFile();
      }
      OutputStream out = new FileOutputStream(destFile);
      CipherOutputStream cos = new CipherOutputStream(out, cipher);
      byte[] buffer = new byte[1024];
      int r;
      while ((r = is.read(buffer)) >= 0) {
        cos.write(buffer, 0, r);
      }
        cos.close();
        out.close();
        is.close();
    } catch (UnsupportedEncodingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (NoSuchAlgorithmException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (NoSuchPaddingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (InvalidKeyException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      flag = false;
    }
    
    return flag;
  }
}

Java Source Code List

• Back to Security/application  ↑