ASCIIWeb is a moderately secure program to take plaintext and convert it into ciphertext. The main purpose of this program is to provide a compatible encryption algorithm that will run on virtually any modern computer and web browser, so that if you are away from your main computer (traveling/at a computer lab/at work) and need to send email in a relatively secure fashion, you can do so regardless of the encryption software present on your current computer. Keep in mind that while ASCIIWeb uses a fairly secure algorithm to encrypt messages, it is unclear how well this cipher stands up to determined cryptanalysis. That being said, if you do not label your correspondence with links to this algorithm, it should be very difficult to decipher the raw text. Also, this cipher is only as strong as your passphrase - be sure to use a lengthy phrase that is hard to guess but easy to remember (RLPassWeb or DiceWare may help you with this). This program contains a limited version of RLPassWeb for direct short-password use - for the full version, use the link above.
ASCIIWeb is based off of the Theta Encryption System for the TI-83 calculator. This is the sixth iteration of the algorithm. The algorithm used is very loosely based on the Vignere cipher method, with a number of enhancements made possible by computerization. Simply put, ASCIIWeb takes your text and uses a Vignere-like cipher to shift it multiple times, each time doing a character-for-character shift with an individual hash created from your password and the session key (the hash itself also changes with each iteration). To see how the program steps through the encryption, a "debug" version is also available (but runs much slower).
New features in 1.0.3 are: "session key" functionality for increased security, easier operation, optimized algorithm for decreased encryption time, added ident option, updated contacts, asciicode dropped in this version: too many unresolved bugs. NOTE: This version of ASCIIWeb is not backward-compatible with previous versions - text encoded with ealier versions CAN NOT be decrypted using this version! If you need to decrypt such text, previous versions are still available on the Products page. Also note that unlike previous versions of the algorithm, plaintext can no longer be "decrypted."
Signed Source Algorithm
©2003 Theta Pi Software
By using or viewing the ASCIIWeb code, you agree to the following License: You may place these pages on your website, as long as you place a link back to Theta Pi Software, and the scripts retain their original and intact code (HTML may be modified, as long as copyright info and actual script remains intact). There are no restrictions on the use of the encrypted data. However, you may not sell ASCIIWeb, or any program containing, either in part or in full, the ASCIIWeb algorithm, HTML, or documentation. You also agree that you are using this program AT YOUR OWN RISK, and to hold David Kibrick and Theta Pi Software harmless from any and all liabilities, such as loss of data, that may result from the use of this program.