Cryptographic tools and hashes

Encryption techniques are used to protect data from unauthorized access. Unlike the checksum algorithms we just discussed, encryption programs can reconstruct the original data with no loss. There are many algorithms available and we will discuss those most commonly used in the Linux/Unix world.

How to do it...

Let's see how to use tools such as crypt, gpg, and base64:

• The crypt command is not commonly installed on Linux systems. It's a simple and relatively insecure cryptographic utility that accepts input from stdin, requests a passphrase, and sends encrypted output to stdout:

$ crypt <input_file >output_file
        Enter passphrase:

We can provide a passphrase on the command line:

$ crypt PASSPHRASE <input_file >encrypted_file

In order to decrypt the file, use this:

$ crypt PASSPHRASE -d <encrypted_file >output_file

• gpg (GNU privacy guard) is a widely used tool for protecting files to ensure that data is not read until it reaches its intended destination...