codebreaker

Codebreaker is a term for a person who attempts to decipher coded or encrypted information without access to the key. In cryptology, a codebreaker conducts cryptanalysis, with the goal of recovering plaintext, keys, or otherwise compromising a cryptosystem. The role is often contrasted with that of a cryptographer, who designs and defends ciphers, and with an attacker who encodes messages.

Codebreaking relies on methods such as frequency analysis, pattern recognition, mathematical analysis, and, increasingly, computational tools. Practitioners may use known-plaintext or chosen-plaintext attacks, exploit weaknesses in system design, or employ statistical and heuristic techniques to infer the correct plaintext. In modern practice, codebreakers may work with digital ciphertext and specialized software, and may also study side-channel information and other operational data.

Historically, codebreaking has played a pivotal role in warfare and intelligence. In the 1930s and 1940s, Polish mathematicians such as Marian Rejewski and colleagues reconstructed the German Enigma machine and laid groundwork that was later expanded by British cryptanalysts at Bletchley Park. Alan Turing, Gordon Welchman, and others developed machines and methods, including the Bombe and advanced analytic techniques, which significantly shortened World War II. After the war, cryptanalysis evolved alongside cryptography, becoming essential to national security, finance, and digital communications. Today, codebreakers work in government, academia, and industry to test systems, assess vulnerabilities, and advance the science of cryptanalysis.