Android Open Source - Easy_File_Encrypt Simple Crypto

• Back to Development/encrypt  ↑

From Project

Back to project page Easy_File_Encrypt.

License

The source code is released under:

Copyright (c) 2011, 2012, Hunter Davis All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are m...

Java Source Code

package com.hunterdavis.easyfileencrypt;
//from  w  w w.j  a  v  a  2  s  . c  o m
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.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

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

/**
 * Usage:
 * 
 * <pre>
 * String crypto = SimpleCrypto.encrypt(masterpassword, cleartext)
 * ...
 * String cleartext = SimpleCrypto.decrypt(masterpassword, crypto)
 * </pre>
 * 
 * @author ferenc.hechler
 */
public class SimpleCrypto {

  public static byte[] encryptBytes(byte[] seed, byte[] cleartext)
      throws Exception {
    byte[] rawKey = getRawKey(seed);
    return encrypt(rawKey, cleartext);
  }

  public static byte[] decryptBytes(byte[] seed, byte[] encrypted)
      throws Exception {
    byte[] rawKey = getRawKey(seed);
    return decrypt(rawKey, encrypted);
  }

  public static String encrypt(String seed, String cleartext)
      throws Exception {
    byte[] rawKey = getRawKey(seed.getBytes());
    byte[] result = encrypt(rawKey, cleartext.getBytes());
    return toHex(result);
  }

  public static String decrypt(String seed, String encrypted)
      throws Exception {
    byte[] rawKey = getRawKey(seed.getBytes());
    byte[] enc = toByte(encrypted);
    byte[] result = decrypt(rawKey, enc);
    return new String(result);
  }

  public Boolean encryptFile(File in, File out, String seed) throws IOException,
      InvalidKeyException {
    byte[] raw = null;
    try {
      raw = getRawKey(seed.getBytes());
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = null;
    try {
      cipher = Cipher.getInstance("AES");
    } catch (NoSuchAlgorithmException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (NoSuchPaddingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
    

    FileInputStream is = new FileInputStream(in);
    CipherOutputStream os = new CipherOutputStream(
        new FileOutputStream(out), cipher);

    copy(is, os);

    os.close();
    return true;
  }
  


  public Boolean decryptFile(File in, File out, String seed)  throws IOException,
  InvalidKeyException {
    byte[] raw = null;
    try {
      raw = getRawKey(seed.getBytes());
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = null;
    try {
      cipher = Cipher.getInstance("AES");
    } catch (NoSuchAlgorithmException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (NoSuchPaddingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    
    CipherInputStream is = new CipherInputStream(new FileInputStream(in),
        cipher);
    FileOutputStream os = new FileOutputStream(out);

    copy(is, os);

    is.close();
    os.close();
    return true;
  }
  
  private void copy(InputStream is, OutputStream os) throws IOException {
      int i;
      byte[] b = new byte[1024];
      while((i=is.read(b))!=-1) {
        os.write(b, 0, i);
      }
    }

  private static byte[] getRawKey(byte[] seed) throws Exception {
    KeyGenerator kgen = KeyGenerator.getInstance("AES");
    SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
    sr.setSeed(seed);
    kgen.init(128, sr); // 192 and 256 bits may not be available
    SecretKey skey = kgen.generateKey();
    byte[] raw = skey.getEncoded();
    return raw;
  }

  private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
    byte[] encrypted = cipher.doFinal(clear);
    return encrypted;
  }

  private static byte[] decrypt(byte[] raw, byte[] encrypted)
      throws Exception {
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    byte[] decrypted = cipher.doFinal(encrypted);
    return decrypted;
  }

  public static String toHex(String txt) {
    return toHex(txt.getBytes());
  }

  public static String fromHex(String hex) {
    return new String(toByte(hex));
  }

  public static byte[] toByte(String hexString) {
    int len = hexString.length() / 2;
    byte[] result = new byte[len];
    for (int i = 0; i < len; i++)
      result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
          16).byteValue();
    return result;
  }

  public static String toHex(byte[] buf) {
    if (buf == null)
      return "";
    StringBuffer result = new StringBuffer(2 * buf.length);
    for (int i = 0; i < buf.length; i++) {
      appendHex(result, buf[i]);
    }
    return result.toString();
  }

  private final static String HEX = "0123456789ABCDEF";

  private static void appendHex(StringBuffer sb, byte b) {
    sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
  }

}

Java Source Code List

• Back to Development/encrypt  ↑