Glossary

Cryptography (Crypto) - Cryptography is a mathematical process of encrypting (scrambling) information, for example, the text "Hello World" can be encrypted into "1($f#%g*T" until decrypted into the original information, this is done by changing the 'value' (Hex, Binary, Oct,..etc...) of the characters, and by adding false values. Encrypted text does not have to have the same number of characters as the original text. Example from the novel: "The math behind crypto is good and solid, and you and me get access to the same crypto that banks and the National Security Agency use."

Decryption (Decrypt) - Decryption is the process of un-encrypting a piece of information, returning the scrambled information into its original, readable state. For example. Turning the "1($f%g*T" from above back into "Hello World". Example from novel: "I want you to unlock this phone and then decrypt the files in its memory" (Carrie Johnstone to Marcus)

Key - A key is something that is used to encrypt information in an unique way. For example, if you encrypted information with the key "Hello World 1", the result would be different than if the key was "Hello World 2", and the same would apply when decrypting information. Because of this, it is very difficult to decrypt an encrypted piece of information without the key. In the novel, this is used so other people cannot decrypt the secret messages Marcus sends without his key. Example from novel: Turing could figure out how to crack any Nazi message, no matter what key it used

Cipher - A cipher is the 'rule' used to encrypt information, for example, a character's hex value can be changed so it is two times the original value,  or it can be changed in other ways, so it's unpredictable. Machines that try different ciphers and different keys in very high speeds have been invented to solve this, but with a really complicated Cipher, machines will always get stuck at a certain point. Example from novel: "Any time you had a cipher, you were vulnerable to someone smarter than you coming up with a way of breaking it."


Bayesian Analysis - Bayesian statistics and analysis covers a very large area of mathematics, but the use of Bayesian analysis mentioned in this book is the type used in spam filters and related technological uses, this is where every word in 'spam' files are counted to make a word histogram, and the same for non-spam files. This way, other files that contain the words that appeared the most in spam files would be considered spam, and the same for non-spam files. Bayesian analysis can be used on pretty much anything, including pictures, which can be sorted by the patterns of the pixels. Example from book: "It's part of something called Bayesian analysis and it's been around for centuries now. Without it, we couldn't do spam­filtering.