Cryptography before the modern era was synonymous with encryption, the conversion of information into a readable state into a non-sensitive one. The sender of an encrypted message shares the decoding technique with only the intended recipients to prevent access to adversaries. The cryptography literature often uses the names Alice ("A") for the sender, Bob ("B") for the intended recipient and Eve ("eavesdropper"). Since the development of rotor encryption machines during the First World War and the advent of computers in the Second World War, the methods used to perform cryptology have become more and more.
Modern cryptography is strongly based on mathematical theory and computer practice; Cryptographic algorithms are designed around the calculation of hardness of assumptions, which make these algorithms difficult to practice in any adversary. It is theoretically possible to break such a system, but it is impossible to do so by any known practical means. These diagrams are therefore qualified as secure by calculation; these solutions are continuously adapted to require interactive factorization algorithms and faster computer technology for theoretical progress, for example.
Cryptanalysis of new mechanical devices has proven to be both difficult and laborious. In the United Kingdom, repetitive tasks performed for more efficient means of World War II spurred development during Bletchley Park's cryptanalytic efforts. The Colossus is the first fully electronic, digital and programmable computer in the world, which helped decrypt the numbers generated by the German army from the Lorenz SZ40 / 42 machines.