Javascript must be enabled for this encryption/decryption demo

I use my blog as literally an online journal to record my activities and thoughts so I can look back at them later. Writing things down can also be therapeutic. As a side benefit, it serves as a form of communication with my friends and randoms (it helped me get my apartment).

The problem is that I have to constantly censor myself as I do not want other people reading some of my more personal thoughts, especially ones about people that read my blog. I want my blog to be public, but I want to also add some private text.

My solution is to use cryptography. I will encrypt text I don't want people to read, this way the text is not available anywhere (not even on the server). The difficulty is in making it easy to do both encryption and decryption and doing so in a secure manner, i.e. do everything locally.

I turned to Javascript, as it is ubiquitous and it would allow me to do client side decryption. I found this site that uses Javascript to do 256-bit AES encryption and decryption. This encryption was more than enough for my purposes.

I then modded the code to do dynamic text with CSS. The result is the little demo at the top. When you enter the key into the prompt box, it decrypts the scrambled text on the fly without reloading the page! Better yet, it's all done locally, so not even the server ever sees the plain text.


Here's how you can use it for your site:

1. Encrypt your text (be sure to remember the key!)


2. Download the decryption Javascript code and include it in the header of your blog/site


3. Use one of the two following code templates to put the encrypted text and decryption link on your page, depending on whether or not you want the encrypted text to show by default.
   
   
   • Show the encrypted text on the page along with a link to decrypt it
     
     
     <a href="javascript:Decrypt_text('unique_name');">Decrypt text</a>

<div id="unique_name">Encrypted text from step 1</div>
     
   
   
   • Hide the encrypted text and only show the decryption link
     
     
     <a href="javascript:Decrypt_text('unique_name', 'Encrypted text from step 1');">Show encrypted text</a>

<div id="unique_name"></div>
     
   
   Note 1: "unique_name" is the ID of the div (it appears in both lines of code) and ID's, have to be unique. In other words, if you use this code multiple times for multiple blocks of encrypted text, you have to change "unique_name" to "encrypted", "encrypted2", "encrypted_text_about_bob", etc. because the same name cannot be used twice.

The encrypted text is secure as long as you keep the key secret. The key is like a super-ultra secure password. You can use the same key over and over for multiple encryptions (so you don't have to remember/store multiple keys). If you want select people to see the encrypted text, you can give them the key. You may want to use a set of keys, one for super private, one for the gf, one for close friends, etc.

FAQ

1. Is this secure?
   • Yes, the encryption used is very secure.


2. Is there a back door? Can you read my encrypted text?
   • No. No one without the key can read the encrypted text and I don't know how to make a good back door.


3. Is this going to install bad stuff on my computer or break stuff? Is this adware crap? Is this a virus?
   • No. I don't know how to do that.


4. I lost the key, can you help me decrypt the text?
   • No. You lose the key and there's pretty much no way to decrypt the text, that is, until we get quantum computers.


5. Do you have a quantum computer?
   • Yes, but I don't know how to use it.

Disclaimer: Not to be used if encryption is illegal in your country or used for illegal purposes.


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Posted by BambangOke at 4:24 PM | Permalink | Comments | links to this post