From Citizendium, the Citizens' Compendium
- See also changes related to Cryptography, or pages that link to Cryptography or to this page or whose text .
- Information security : The set of policies and protective measures used to ensure appropriate confidentiality, integrity and availability to information; usually assumed to be information in a computer or telecommunications network but the principles extend to people and the physical world
- Cryptology : The theory and practice of protecting the content of communications, and of defeating the protective measures
- Information theory : Theory of the probability of transmission of messages with specified accuracy when the bits of information constituting the messages are subject, with certain probabilities, to transmission failure, distortion, and accidental additions.
- Signals intelligence : the practice of acquiring information through monitoring the electromagnetic signals deliberately trasmitted by an opponent, including communications (COMINT) and non-communications electronics such as radar (ELINT).
- Communications intelligence : The subset of SIGINT concerned with signals intended to be intelligible to human beings, in the form of voice, messages, or images.
Modes of encryption
- Bulk encryption : The encipherment of all traffic on a digital transmission medium, without awareness of multiplexed channels, data link protocols, etc., in the medium.
- Message encryption : Add brief definition or description
- IPsec : Internet Protocl security is a set of protocols for providing encryption and/or authentication services for Internet packets.
- Secure Sockets Layer : Add brief definition or description
- Transport Layer Security : Add brief definition or description
- Cipher : A means of combining plaintext (of letters or numbers, or bits), using an algorithm that mathematically manipulates the individual elements of plaintext, into ciphertext, a form unintelligible to any recipient that does not know both the algorithm and a randomizing factor called a cryptographic key
- Alphabetic substitution : Add brief definition or description
- Advanced Encryption Standard : A US government standard issued in 2002 for a stronger block cipher to succeed the earlier Data Encryption Standard.
- Data Encryption Standard : A block cipher specification issued by the U.S. government in 1976, intended for sensitive but unclassified data. It is now obsolescent, succeeded by the Advanced Encryption Standard, but still used in commercial systems.
- Diffie-Hellman : A technique that allows two parties to safely establish a shared secret for use as a cryptographic key, even if someone is eavesdropping on their interaction. It requires that the parties have some means of authentication to be sure they are talking to the right person.
- Enigma machine : The primary high-security cryptographic communications security machine of Nazi Germany. Unknown to the Germans, it had been substantially cryptanalyzed by the British Government Code and Cipher School, with French, Polish, and U.S. help.
- Feistel cipher : Add brief definition or description
- Hagelin machine : Add brief definition or description
- One-time pad : A cipher system in which the cryptographic key, i.e. the secret used to encrypt and decrypt messages, is a sequence of random values, each one of which is only ever used once, and only to encrypt one particular letter or word.
- Playfair cipher : Add brief definition or description
- Pretty Good Privacy : E-mail encryption package created by Phillip Zimmerman.
- Rotor machine : Add brief definition or description
- Vigenère cipher : Add brief definition or description
- PURPLE machine : WWII Japanese cipher machine used for diplomatic communications; system broken by U.S. and made available to U.K. in exchange for ULTRA communications intelligence on Germany
- SIGABA : Add brief definition or description
- Quantum cryptography : Add brief definition or description
- TACLANE : A family, designated TSEC/KG-175, of bulk encryption devices specified by the National Security Agency, which work with high-speed IEEE 802.3/Ethernet interfaces
- FASTLANE : A family of U.S. National Security Agency approved encryption devices for Asynchronous Transfer Mode (ATM), Synchronous Digital Hierarchy (SDH) and Synchronous Optical Network (SONET) transmission systems
- Code (cryptography) : A means of substituting, for the linguistically meaningful symbols of plaintext composed of words or other symbols meaningful to humans, into inherently meaningless numbers, letters, or words that make no sense to a recipient who is not in possession of a codebook or other means of reversing the substitution of symbols
- Cryptanalysis : The sub-field of cryptology which deals with breaking into existing codes and ciphers.
- ULTRA : ULTRA was the main code word, in the Second World War, for British signals intelligence directed at Nazi Germany.
- Internet Key Exchange : Add brief definition or description
- Key generation (cryptographic) : Add brief definition or description
- Key management (cryptographic) : Add brief definition or description
- Session key : Add brief definition or description
- Claude Shannon : (1916-2001) A theoretical mathematician and electrical engineer, one of the foundational researchers in computer and communications design.
- William Friedman : Possibly the greatest cryptologist in history, he pioneered the application of mathematics to cryptanalysis and built the U.S. Army Signal Intelligence Service technical base.
- Auguste Kerckhoffs : A 19th Century French writer, famous for giving some axioms for cryptography.
- Alan Turing : British mathematician, code breaker and computer pioneer.
- Communications Security Establishment : The Canadian government organization responsible for communications security and signals intelligence
- Defense Signals Directorate : Signals intelligence and information security organization of Australia
- FAPSI : A communications intelligence and information security organization in Russia, which became independent of the KGB at the end of the Soviet Union, but now has been absorbed back into the FSB
- Government Communications Headquarters : The British government agency responsible for signals intelligence and information assurance
- Government Communications Security Bureau : The organization, in the government of New Zealand, which has responsibility for information security and signals intelligence
- National Security Agency : An organization within the United States Department of Defense, with the dual roles of the principal signals intelligence agency in the United States intelligence community, but also having the responsibility for information assurance of military, diplomatic, and other critical communications.
- Politics of cryptography : Political and legal controversy over the use and export of cryptography
- Privacy : Add brief definition or description
- Steganography : The study of techniques for hiding a secret message within an apparently innocent message.
- Covert channel : Add brief definition or description
- Authentication : Add brief definition or description
- Digital certificate : A means by which the user of a public key can obtain it from a central repository, with high confidence that key is correct and has not been revoked
- Digital signature : A technique based on public key cryptography to allow people to "sign" documents using their private keys.
- Extensible Authentication Protocol : Add brief definition or description
- Public Key Infrastructure : Add brief definition or description
- Random number generator : A member of a sequence of which the successive values cannot be predicted, produced by measurement of physical phenomena, appropriate algorithms, or a combination of the two
- Unicity distance : Add brief definition or description
- Zero-knowledge protocol : Add brief definition or description