Cryptosmith

A while back I wrote a post to explain the one-time pad encryption technique. It goes along with other pages that explain some fundamental cryptographic concepts.

It’s amazing how subtle a one-time pad really is. On one level they’re deceptively simple: you simply match up the text of your message with a collection of “random bits” you share with the recipient. To decrypt, the recipient matches up a copy of those “random bits” to retrieve the message.

The trick is in the definition of “random bits.” Continue Reading »

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Take a look at the following image. You should see two different ‘messages’ here.

Two messages

This particular mis-mash of messages reflects the failure of otherwise strong cryptography: the improper implementation of a one-time pad or a stream cipher. Continue Reading »

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The one-time pad is the only encryption technique that has been mathematically proven to be uncrackable. While hard to use, it has often been the choice for highly sensitive traffic. Soviet spies used one-time pads in the 1940s and -50s. The Washington-Moscow “hot line” also uses one-time pads. However, the technique is hard to use correctly.

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The exclusive or operation - a logical function applied to binary bits, like AND, OR, and NOT - is a fundamental encryption technique. It is often used in stream ciphers, which are widely used in web browsers when connecting to secure web servers. Continue Reading »

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