Alpha Crypt Text Message Encryptor

Alpha Crypt uses MD5 cryptographic signatures on top of an XOR text encryption algorithm to form a practically unbreakable hybrid.


Alpha Crypt is designed for sending messages from anywhere on the Internet, without access to other encryption software. AC will not become confused by text wrapping, missing text, or other mistakes that occur during transmission. By running along a 64-character set, it will not garble binary values, or cause a browser to crash. Other encryption methods can lose the ability to decrypt a message when any part of the message is corrupted or garbled. Alpha Crypt does not have this weakness, but rather it maintains security while preserving the ability to decrypt virtually any intact / un-garbled portion of a message, no matter how garbled the remainder of the message is. For this reason, it is especially suited for personal use in conjunction with accounts at public free email providers.


Alpha Crypt defeats word-based or probability-based attacks, as well as overcoming methods which measure statistics based on consistent input-output.


Alpha Crypt is faster than other programs, by reducing cryptology running time primarily to internal bit operations, compatible with JavaScript browsers, instead of auxiliary functions.

Encrypt or decrypt messages

Key: Time:

Critical warranty and other information

Alpha Crypt is offered as-is, without warranty. Although I would feel safe in saying that no one can read a message I send with Alpha Crypt, I do not wish to make any legally binding guarantees, express or implied. You have the freedom to be secure, but freedom is also your own responsibility. I take no liability from any use of this software.


If you plan on emailing the contents of an encrypted message, you may wish to include the following note with the encrypted text:

Note: This message was encrypted with Alpha Crypt for safe transmission. Select and copy the message text, and visit to decrypt the message (a password key is required).

In order to distribute the load from many people using Alpha Crypt, this message is dynamically updated to show the current URL. This way, many websites may post these files and share Alpha Crypt. However, if you wish, you may also use the master url: Alpha Crypt by Joseph Myers

<a href="">Alpha
Crypt by Joseph Myers</a>

Correction of some published concerns about Alpha Crypt based on the phrase "XOR encryption"

The XOR'ing of side-by-side streams of data is used in Alpha Crypt as an arithmetic method in some steps for efficiency, but is not the basis for encryption.

Particularly, Alpha Crypt is not vulnerable to well-known trivial attacks on so-called "XOR encryption" when known messages or multiple unknown messages have been encrypted with the same key stream. Alpha Crypt uses a variable, never-repeating bit stream for encryption, and is definitely never vulnerable to the recovery of the original key. An encrypted message can theoretically be recovered only if the message itself is already known (and in which case the key can still not be determined except by guessing all strings). It should be obvious that an encryption method which requires all key strings to be guessed even in the case when both the encrypted and original messages are fully known, is extremely secure.

Fake XOR "encryption" practices have become commonplace after the implementation of Alpha Crypt encryption, and unfortunately the infamy of their weaknesses is affecting the reputation of Alpha Crypt. The historic description of Alpha Crypt is being kept since it is prior art to other so-called "XOR encryption" methods (which aren't really encryption at all).


For distribution, a zip file is available, (5.15 KB: contains alphac.html, timer.js, md5.js, and alphac.js).

Libraries used

Originally from Alpha Crypt by Joseph Myers. MD5 code (md5.js) by Joseph Myers is based on md5.js by Paul Johnston and Greg Holt.

Modified copies of programs in this list are used:

Joseph K. Myers, 2002/10/10, v.2 2003/11/13, cookies @