Large File Encryption is Too Slow!! Help

Question

I am trying to write some methods to handle encryption of zip files, most are very large (over 200 mb). At first it was attempted to load the file into memory, create a Base64encoded string and encrypt that back out to a file. But not nearly enough memory to do that, and generally as files get larger, it would not be possible to support that. So instead I am opting for something like CipherOutputStreams, read in, write out without buffer. on Small files, this is great (smaller than 1 mb) as it happens instantly. But when it get up to the 200MB minimum size of our zips, it takes hours. Is there any way I can speed this up? (See code below)
import java.util.*;
import java.io.*;
import java.util.zip.*;
import javax.crypto.*;
import javax.crypto.spec.*;
public class EncryptedZipUtil
  private static final String ALGO = "DESede";
  private static final String CIPHER_ALGO = "DESede/CBC/PKCS5Padding";
  private static final byte[] IV_PARAMS = new byte[] {
          127, 111, 13, 120, 12, 34, 56, 78
  private static final String ENCODING = "UTF-8";
  private static final byte[] ENCRIPTION_KEY = "Encryption key must be at least 30 characters long".getBytes();
  private static Cipher getCipher(int mode) throws Throwable
      DESedeKeySpec spec = new DESedeKeySpec(ENCRIPTION_KEY);
      SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGO);
      SecretKey theKey = keyFactory.generateSecret(spec);
      Cipher dcipher = Cipher.getInstance(CIPHER_ALGO);
      IvParameterSpec IvParameters = new IvParameterSpec(IV_PARAMS);
      dcipher.init(mode, theKey, IvParameters);
      return dcipher;
  public static ZipInputStream getDecryptedZipStream(File f) throws SecurityException, IOException
    FileInputStream fin = new FileInputStream(f);
    return new ZipInputStream(new CipherInputStream(fin,getCipher(Cipher.DECRYPT_MODE)));
  public static void streamEncryptZipFile(File zipFile, File outzip) throws Throwable
    FileInputStream fin = new FileInputStream(zipFile);
    CipherOutputStream cos = new CipherOutputStream(new FileOutputStream(outzip),getCipher(Cipher.ENCRYPT_MODE));
    while(fin.available() != 0)
      cos.write(fin.read());
    fin.close();
    cos.close();
  public static void streamDecryptZipFile(File e_zipFile, File outzip) throws Throwable
    CipherInputStream cin = new CipherInputStream(new FileInputStream(e_zipFile),getCipher(Cipher.DECRYPT_MODE));
    FileOutputStream fos = new FileOutputStream(outzip);
    int the_byte = -1;
    while((the_byte = cin.read()) != -1)
      fos.write(the_byte);
    cin.close();
    fos.close();
  public static void main(String[] args) throws Throwable
    EncryptedZipUtil.streamEncryptZipFile("D:\\ziptest\\original.zip","D:\\ziptest\\encrypted.zip");
    EncryptedZipUtil.streamDecryptZipFile("D:\\ziptest\\encrypted.zip","D:\\ziptest\\decrypted.zip");
}Like I said, the code here works great with small files. Quick, correct and simple. My Machine is 2.8ghz P4, with 1024mb Ram, and when I run this on my larger files, it uses 99% CPU and no memory in addition to the standard JVM Heap.
Any advice would be greatly appreciated

Answer 1

Nice answer, but for additional duke points I've though of an issue with it: although this defeintly speeds up encrypt/decrypt time, there is no longer any way for me to access this file as a stream directly: if you see the method getDecryptedZipStream(File f), since the file is generally a zip, getting a stream in this manner wont work if we want to thumb through the contents and extract entries on the fly, because now the encryption is done in chunks rather than by bytes which the underlying stream would be should we want to browse the zip. So this solution doesn't solve all aspects of the issue. My alternative was then to imagine that I would enncrypt the individual contents of the zips prior to zipping and leave the zip intact. I could the browse the zip but can not access any of the data without decrypting each file first. I don't know if that is the best solution as of yet.