# Popular maths talks

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## History of cryptography

University of Salford (06/03/2012).

Abstract:

Cryptography is the process by which messages are communicated through secret means. Cipher cryptography converts messages by applying some cipher algorithm with a secret key to a plaintext message, converting it into a ciphertext message that cannot be read by interceptors. Cryptanalysis is the science that attempts to decipher these messages without access to the secret key.

This talk will introduce substitution ciphers and demonstrate the processes of encrypting and breaking some examples of these. As cryptanalysis develops, more ingenious ciphers must be created in a constant between cryptographers and cryptanalysts. Later, cryptography becomes mechanised and the efforts of codebreakers at Bletchley Park in World War II will be briefly decribed. Later still, cryptography becomes computerised and an idea will be given of Public key cryptography.

This talk will provide a gentle introduction and will assume no prior knowledge of cryptography.