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15th Century Encryption · 2005-05-13

What we have here, if we had javascript enabled, is an implementation of a very famous symmetric encryption algorithm. It is an old algorithm based on swapping characters according to a 'passphrase' and alledgedly invented by Leone Battista Alberti. It is one of the polyalphabetic algorithms. It serves very well for short messages. It even is unbreakable, given one uses passphrases, that are at least as long as the message. For long messages it failes miserably, for one can attack it using statistical methods.

How to use it: Choose a passphrase. Type it to the 'passphrase' field. Type your message to the 'message' field. Click the 'encrypt' button. The encrypted message appears. To decrypt a message type it to the message field and press decrypt. Since we use javascript to deploy the algorithm, no information is transmitted through the net, by the way.

Of course the whole thing is more or less proof of concept. It is only tested with Mozilla 1.7. See the code here if you are interested: encrypt.js


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