WikiNow lets you discover the news you care about, follow the topics that matter to you and share your favourite stories with your friends.

© WikiNow

Cryptography or cryptology is the practice and study of techniques for secure communication in the presence of third parties called adversaries. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce.

Lorenz cipher machine twelve rotors with mechanism
German Lorenz cipher machine, used in World War II to encrypt very-high-level general staff messages

Cryptography or cryptology (from Greek κρυπτός kryptós, "hidden, secret"; and γράφειν graphein, "writing", or -λογία -logia, "study", respectively) is the practice and study of techniques for secure communication in the presence of third parties called adversaries. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce.

Cryptography prior to the modern age was effectively synonymous with encryption, the conversion of information from a readable state to apparent nonsense. The originator of an encrypted message (Alice) shared the decoding technique needed to recover the original information only with intended recipients (Bob), thereby precluding unwanted persons (Eve) from doing the same. The cryptography literature often uses Alice ("A") for the sender, Bob ("B") for the intended recipient, and Eve ("eavesdropper") for the adversary. Since the development of rotor cipher machines in World War I and the advent of computers in World War II, the methods used to carry out cryptology have become increasingly complex and its application more widespread.

Modern cryptography is heavily based on mathematical theory and computer science practice; cryptographic algorithms are designed around computational hardness assumptions, making such algorithms hard to break in practice by any adversary. It is theoretically possible to break such a system, but it is infeasible to do so by any known practical means. These schemes are therefore termed computationally secure; theoretical advances, e.g., improvements in integer factorization algorithms, and faster computing technology require these solutions to be continually adapted. There exist information-theoretically secure schemes that provably cannot be broken even with unlimited computing power—an example is the one-time pad—but these schemes are more difficult to implement than the best theoretically breakable but computationally secure mechanisms.

The growth of cryptographic technology has raised a number of legal issues in the information age. Cryptography's potential for use as a tool for espionage and sedition has led many governments to classify it as a weapon and to limit or even prohibit its use and export. In some jurisdictions where the use of cryptography is legal, laws permit investigators to compel the disclosure of encryption keys for documents relevant to an investigation. Cryptography also plays a major role in digital rights management and copyright infringement of digital media.

Cryptography: Crash Course Computer Science #33

Today we're going to talk about how to keep information secret, and this isn't a new goal. From as early as Julius Caesar's Caesar cipher to Mary, Queen of ...

Cryptography For Beginners

Cryptography is a complex and confusing subject. In this talk you will learn about the core components of cryptography used in software development: securing ...

Cryptography: The Science of Making and Breaking Codes

There are lots of different ways to encrypt a message, from early, simple ciphers to the famous Enigma machine. But it's tough to make a code truly unbreakable.

Lecture 1: Introduction to Cryptography by Christof Paar

For slides, a problem set and more on learning cryptography, visit www.crypto-textbook.com. The book chapter "Introduction" for this video is also available for ...

Cryptography 101 - The Basics

In this video we cover basic terminology in cryptography, including what is a ciphertext, plaintext, keys, public key crypto, and private key crypto.

A Short History of Cryptography - A Brief History of Cryptography

A Short History of Cryptography - A Brief History of Cryptography.