lock.java

/* Initial implementation for a folder lock
 * Author: Ankur Shrivastava
 * License: GPLv3
 */
import java.io.*;
import java.util.Enumeration;
import java.util.zip.*;

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

import java.security.MessageDigest;

class Lock
{
    public static void main (String args[])
    {
        // functions here
    }
    
    public static void unzip(String filename)
    {
        /*  takes filename as agrument and unzips the file
         */
        try
        {
            FileInputStream fis = new FileInputStream(filename); // read the file
            ZipInputStream zis = new ZipInputStream(fis); // open file in zip stream
            byte buf[] = new byte[1024]; // buffer to hold temperory data
            ZipEntry entry; // to hold file entries
            entry = zis.getNextEntry(); // get file entery
            while (entry != null) // loop till we have entries
            {
                System.out.println("Name-> " + entry.getName()); 
                System.out.println("CSize-> " + entry.getCompressedSize());
                System.out.println("Size-> " + entry.getSize());
                FileOutputStream fos = new FileOutputStream("New-" +entry.getName()); // open file for entry
                int len;
                while ((len = zis.read(buf,0,buf.length)) != -1) // loop till end of data for the file
                {
                    fos.write(buf,0,len); // write data in uncompressed file
                }
                fos.close(); // close file
                entry = zis.getNextEntry(); // get next file
                System.out.println();
            }
        }
        catch (Exception e) // catch all exceptions #TODO proper clean up
        {
            System.out.println("Error " + e);
        }
    }

    public static void zip(String files[],String filename)
    {
        /* Takes array of files to be ziped
         * zipes and stores them in the file -> filename
         */
        try
        {
            FileOutputStream fos = new FileOutputStream(filename); // open file to be written
            ZipOutputStream zos = new ZipOutputStream(fos); // open the zip stream
            byte buf[] = new byte[1024]; // data buffer
            ZipEntry entry; // entry
            for (int i =0; i< files.length;i++) // go through files one by one
            {
                entry = new ZipEntry(files[i]);// init entry
                zos.putNextEntry(entry); // add entery to zip file
                FileInputStream fis = new FileInputStream(files[i]); // read teh file
                int len;
                while ((len = fis.read(buf,0,buf.length)) != -1) // read till end
                {
                    zos.write(buf,0,len); // write file entry
                }
                fis.close();
                zos.closeEntry();
            }
            zos.close();
        }
        catch (Exception e) // catch all exceptions #TODO proper cleanup
        {
             System.out.println("Error " + e);           
        }
    }

    public static byte[] getKey(String password)
    {
        /*
         * Takes a string as input and returns its MD5 in byte[]
         */
        try
        {
            MessageDigest md5 = MessageDigest.getInstance("MD5"); // get the MD5 instance
            return md5.digest(password.getBytes()); // get md5 of key ( byte[] )
        }
        catch(Exception e)
        {
              System.out.println("Error " + e);                    
        }
            return new byte[1];
    }

    public static void encrypt(String filename, String password)
    {
        /*
         * Takes filename and password as argument and creates a encrypted file by name filename.enc
         */
        try
        {
            FileInputStream fis = new FileInputStream(filename); // file to be encrypted
            FileOutputStream fos = new FileOutputStream(filename+".enc"); // encrtpted file
            byte[] keyBytes = getKey(password); // get md5 hash of the password
            SecretKeySpec key = new SecretKeySpec(keyBytes,"AES"); // secret key for aes
            Cipher cipher = Cipher.getInstance("AES"); // get cipher
            cipher.init(Cipher.ENCRYPT_MODE,key); // init cipher
            CipherInputStream cis = new CipherInputStream(fis,cipher); // get chiper input stream, to read teh file
            byte buf[] = new byte[1024];
            int len;
            while( (len = cis.read(buf,0,buf.length)) != -1) // read till end
            {
                fos.write(buf,0,len); // write out to encrypted file
            }
            cis.close();
            fos.close();
            fis.close();
        }
        catch (Exception e) // catch all exceptions #TODO proper cleanup
        {
            System.out.println("Error " + e);
        }
    }

    public static void decrypt(String filename, String password)
    {
        /*
         * Takes filename and password as arguments and decrypts file "filename.enc" stores it as filename
         */
        try
        {
            FileInputStream fis = new FileInputStream(filename+".enc"); // file to be decrypted
            FileOutputStream fos = new FileOutputStream(filename); // decrtpted file
            byte[] keyBytes = getKey(password); // get md5 hash of the password
            SecretKeySpec key = new SecretKeySpec(keyBytes,"AES"); // secret key for aes
            Cipher cipher = Cipher.getInstance("AES"); // get cipher
            cipher.init(Cipher.DECRYPT_MODE,key); // init cipher
            CipherInputStream cis = new CipherInputStream(fis,cipher); // get chiper input stream, to read teh file
            byte buf[] = new byte[1024];
            int len;
            while( (len = cis.read(buf,0,buf.length)) != -1) // read till end
            {
                fos.write(buf,0,len); // write out to encrypted file
            }
            cis.close();
            fos.close();
            fis.close();
        }
        catch (Exception e) // catch all exceptions #TODO proper cleanup
        {
            System.out.println("Error " + e);
        }
    } 
}