A handful of arcane mathematicians way back in the 18th and 19th centuries aspired to invent a useless mathematical theory that would shine for its beauty alone, unstained by practical applications.

Introduction to ciphers and substitution. Alice and Bob and Carl and Julius: terminology and Caesar Cipher ; The key to the matter: generalizing the Caesar Cipher ; Multiplicative ciphers ; Affine ...

Encryption, the transformation of data into a form that prevents anyone unauthorized from understanding that data, is a fundamental technology that enables online commerce, secure communication, and ...

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Public-key encryption, as noted in the profile of cryptographer Bruce Schneier, is complicated in detail but simple in outline. The article below is an outline of the principles of the most common ...