Encrypting Files

Encrypting files is very much like encrypting strings. However, with large files, it may be wise to empty the cipher streams. However, if the file is too large, or if there are multiple files, then it may be wise to apply CipherStreams—not to be confused with Stream Cipher.

CipherStreams inherit most of their behavior from InputStream and OutputStream of Java, with the modification that you can decrypt a file you read, or encrypt a file you write with the supplied cipher.

Exercise 3: Encrypting a File

The following exercise displays how to encrypt a file. You can find this file in the code repository.

1. Open the Chapter10 project in IDEA if it's not already open.
2. Create a new Java class, using the File | New | Java Class menu.
3. Enter Exercise3 as Name, and then select OK. You should now have an empty class in your project:

   package com.packt.java.chapter10;
   public class Exercise3 {
   }

4. Add a main method in which you'll write the...