x = Cryptography

"Substitution ciphers: Ancient - Renaissance"

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 focus on substitution ciphers and demonstrate the processes of encrypting and breaking some examples of these. The focus is on the battle between cryptographers - who create cipher systems - and cryptanalysts - who attempt to break them. As cryptanalysis develops more ingenious ciphers must be created and this constant struggle evolves from Roman generals, through the Golden Age of Islam to political intrigue in Renaissance Europe.
This talk will provide a gentle introduction and will assume no prior knowledge of cryptography.

2. Get the article

An article on this topic, "Ciphers through the ages" by Peter Rowlett, appears in issue 10 of iSquared Magazine (Winter 2009/10), on pages 24-27. Download issue 10 of iSquared Magazine for free.

3. Get the companion audio podcast

Download companion audio podcast episode to this talk & article, which extends the topic by covering cracking the Vigenere cipher, from the Travels in a Mathematical World podcast.