• loop-AES
  
• dm-crypt
  
• cryptsetup
  
• SD4L
  
• TrueCrypt

Many organisations need to encrypt sensitive files but do not have the funds to buy disk encryption software. Fortunately, there is a good selection of open source software available to download at no charge that offers good functionality. There are many different tools that allow for disk encryption.

To provide an insight into the open source software that is available, we have compiled a list of 5 notable disk encryption tools. Hopefully, there will be something of interest here for anyone who wants easy-to-use data encryption and security.

Most of these tools are command-line only, but they are so simple that even the most CLI-challenged newbie should be able to use them with little effort. All are highly portable, small in size, and have few or no library dependencies.

TrueCrypt encrypts and decrypts files on the fly, as they are loaded or saved, without user intervention. TrueCrypt can encrypt files and store them in a container file that acts as a virtual disk, or make an entire partitions or disk into an encrypted volume in both Microsoft and Linux. The software depends on a personal password or key that you create when configuring a TrueCrypt volume. Without this key, no data on an encrypted volume can be read (not even offline).

In contrast to the cooperative preparations required for setting up private key encryption, such as secret-sharing and close coordination between sender and receiver, you can act entirely on your own to create and publish two numbers that enable anyone, using the RSA encryption formula, to send a private message to you through a public channel. The message becomes "First Class" e-mail, so to speak, as if sealed in an envelope. Using the two numbers you have published, anyone can scramble a message and send it to you. You are the only one who can unscramble it--not even the sender of the message can decrypt the ciphertext.