Scambled Egg is an Open Source cryptography program for Windows and Linux that offers an easy way to decrypt and encrypt messages.

When you start the program for the first time after installation you will notice that the interface is divided into two panes; The Encrypt Mode on the left and the Decrypt Mode on the right.

The left pane displays the original message, the right the encrypted message. To encrypt text paste textual information into the left pane or add it manually. The editor supports rich text, it will for instance retain different font sizes or types.

Various encryption algorithms and codecs are selectable at the top. You can keep the default selection which uses AES and Base64 Codec, or change it to other algorithms like Blowfish or DES3. It is furthermore possible and suggested to add a password which is then needed to decrypt the message.

The decrypt mode pane displays the encrypted information. You can copy and paste the information directly into text documents, emails or message boards on the Internet, or use the Export button at the bottom to add obfuscation to the protection.

Obfuscation? When you select Export, you get the option to save the encrypted message as a png image. An attacker would have to identify the right image before attempting to decrypt the message.

The image is an actual image, which means that you can post it on the Internet or send it as an image attachment via email.

Received messages can be decrypted in the application. If the message is inside an image, you need to import that image. If it is a message, you need to paste that message into the application, select the correct algorithms and the password.

If that’s all correct you get to see the message on the left pane. You need to make sure to add the password to the Decrypt Mode pane before you import encrypted images or messages. You’d otherwise get an error, and adding the password afterwards has no effect on the process anymore.

The developer has posted two example images on the project website. One is a 28 Kilobyte png image that contains the excellent Le Petit Prince by Antoine de Saint Exupery.

The encryption software Scambled Egg is available for download at Google Code.

After that he explains why cryptography is essential for today’s internet communication: “cryptography is necessary when communicating over any untrusted medium, which includes just about any network, particularly the Internet.”

“Cryptography, then, not only protects data from theft or alteration, but can also be used for user authentication. There are, in general, three types of cryptographic schemes typically used to accomplish these goals: secret key (or symmetric) cryptography, public-key (or asymmetric) cryptography, and hash functions, each of which is described below. In all cases, the initial unencrypted data is referred to as plaintext. It is encrypted into ciphertext, which will in turn (usually) be decrypted into usable plaintext.”

After that interesting history lecture he starts with types of cryptographic algorithms over trust models to cryptographic algorithms in action. All supported by lots of figures that makes it easier to understand the concepts.

Take a look at gary kesslers site for the article.

Update: The developer is constantly adding new information to the website. You can now for instance find information about the Open Source encryption software True Crypt on the site, as well as match notes which may be interesting for programmers and math students alike.

Cryptographic algorithms in action furthermore look at the SSL “Family” of secure transaction protocols, IPsec protocol and RSA public key cryptography.

It is a long read that gets technical at times. You will also find lots of outgoing links for additional information about a concept or subject. The introduction nevertheless is one of the best that you will find about cryptography on today’s Internet.