What is CypherBunk?

It offers easy Ad-Hoc encryption for friends.

It uses Symmetric Keys, so you and your friends have to have an agreed upon Cypher Key.

You don't have to have PGP keys or some other setup in advance. You can just encrypt the message and tell them what the key is later.

Can LocalMESS Decrypt My Message?

Nope. I wrote this entirely in Javascript so that no text is submitted to my server. It only stays in your browser.

You'l notice you didn't have to agree to any cookies on my site. That's because I disapprove of tracking people.

Still worried? Well, I encourage you to save this page to your computer and do all your encryption offline to be sure. I wrote this page as a SINGLE HTML file (no links to CSS, JS, or even IMG) so that you can download 1 single file, and it will instantly work on your local machine with no internet (unless you use a URL for a Key, then it needs internet to fetch the Key).

How Secure is CypherBunk?

If you are looking for strong encryption, you are better off exploring PGP with AES/RSA.

While CypherBunk is weaker, it is much more than a simple 1-to-1 cypher. As long as you use a fairly long key, the encryption is "good enough" for most people. It would take a LOT of compute power to be able to crack CypherBunk.

The easiest way to "crack" CypherBunk is to guess the key. So don't treat the Key like a password.

The best cypher keys are ones you could copy and paste from reliably consistent & lengthy sources (I recommend over 100,000 characters for your Cypher Key).

What Key Should I Use?

Web Pages that don't change often make great keys, as we use the HTML on the web page like a giant password.

Linking to eBooks, Dictionaries, Discographies, Glossaries, or other fairly static lists can be a great key.

Don't link to Dynamic Web Pages. Even a page that displays the current date would break, because if the key changes by even 1 character, the message can no longer be decrypted with that URL.

If you and your friends regularly use a specific URL as a Key, you may consider using a URL shortening service like bit.ly, because then you just have to remember the short URL, yet you can have a massive key.

How Do I Know if my Cypher Key is Good Enough?

After you encrypt/decrypt something, click on the Star icon at the top right.

This will show you your Encryption Score.

The higher the score the better, but anything over 50% is decent.

How do I Decrypt a Spreadsheet?

If someone sent you a spreadsheet that was encrypted with CypherBunk, you will need to open it with a text editor (Wordpad, Notepad++, VIM, etc).

It may look like garbage, but just copy the raw text of the document & paste it in as the "Message."

Be sure to set the Cypher Key you and your friends use, and click "Decrypt this Cyphertext."

Static Javascript Keys:

After encrypting/decrypting a message, if you click on the Key icon at the top right you can see a pre-computed Static Key.

Using such a key will increase performance, but you need to ensure that your machine is physically secure, as you will have effectively copied your symmetric key to your hard drive.

These keys can be convenient, as they can be distributed to others to use to decrypt a message.

Use Case:

Alice wants to send an encrypted message to Bob, but they don't have access to their personal computers, but have access to something with a simple web-browser.

Alice accesses this page, types her message, encrypts it with a key that either she and Bob both know, or she could communicate verbally (like a shortened bit.ly link to Lorem Ipsum), and sends the encrypted message to Bob.

Bob sees the message that just looks like numbers, understands this is a cypher text, and waits to be told what key to use to decrypt it.

Alice tells Bob to go to a bit.ly link for the key.

Bob goes to this page, provides the bit.ly link as the decryption key, pastes the encrypted message, and is able to decrypt it successfully.

Troubleshooting:

"Failed to fetch Encryption Key" can mean your URL is invalid or that the Website doesn't allow remote fetching of their content, so you will have to use another site. Libraries like JS or CSS are often good ways around this, because those sites generally WANT you to link to them & they often offer versioned URLs that won't change over time.

"ERROR: Invalid Cypher Key" means the key you are decrypting with does NOT match the key the message was encrypted with. CypherBunk is good at trimming out erroneous characters in the Message, but any variation in the CypherKey will cause it to fail. If you are using a URL as a Key, the site may have changed its content. If you are using pasted text as the Key, you may have copied/pasted differently than the person who encrypted the message. Even 1 character different will break the decryption, so ensure you and your friends have agreed upon the key (including leading/trailing spaces or newlines).