CryptoData

Easily and quickly to encrypt / decrypt:
Private messages via e-mail, blogs, social networks, forums, websites, images, etc

This addon allows you to encrypt and decrypt the text: selected or manually entered text, as well as whole site
The encryption process is based on the US military standard Advanced Encryption Standard (AES)
https://en.wikipedia.org/wiki/Advanced_Encryption_Standard

JavaScript implementation (AES CTR) belongs to Chris Veness:
http://www.movable-type.co.uk/scripts/aes.html

All encryption and decryption is performed only on the client side without the involvement of external resources or Web services.

Examples encrypting the selected portion of text and web-site:
http://www.s3blog.org/crypto-data/examples.html

For users:
* Simply select the plain or encrypted text in your web browser, open the context menu by clicking the right mouse button, and you can easily encrypt or decrypt any text.

* There is also a possibility of automatic decryption.

For webmasters:
* With this extension you can encrypt any content on the server, e.g. html, javascript or images.
Even if website uses a secure HTTPS-connection and access to his page requires HTTP-authentication, it does not mean that you are fully protected!
There are many ways to steal your information, for example by using a proxy, sniffer or Trojan horse program (eg such as Zeus)
But when you use addon CryptoData attacker could only get a set of useless characters!

* For convenience webmasters CryptoData sends cookie s3crypt_site_enable = true to the encrypted site. Thus, the site can recognize that the client has CryptoData and it can get the encrypted content.

* An example of the implementation of the encryption algorithm on the server side:
http://www.s3blog.org/crypto-data.html

forums mozillaZine:
http://forums.mozillazine.org/viewtopic.php?t=2902265