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Kerckhoffs's principle. Kerckhoffs's principle (also called Kerckhoffs's desideratum, assumption, axiom, doctrine or law) of cryptography was stated by Dutch-born cryptographer Auguste Kerckhoffs in the 19th century. The principle holds that a cryptosystem should be secure, even if everything about the system, except the key, is public knowledge.
Cryptography. Cryptography, or cryptology (from Ancient Greek: κρυπτός, romanized : kryptós "hidden, secret"; and γράφειν graphein, "to write", or -λογία -logia, "study", respectively [ 1] ), is the practice and study of techniques for secure communication in the presence of adversarial behavior. [ 2]
ElGamal encryption can be defined over any cyclic group, like multiplicative group of integers modulo n if and only if n is 1, 2, 4, p k or 2p k, where p is an odd prime and k > 0. Its security depends upon the difficulty of a certain problem in related to computing discrete logarithms.
In Shared Key authentication, the WEP key is used for authentication in a four-step challenge–response handshake: The client sends an authentication request to the access point. The access point replies with a clear-text challenge. The client encrypts the challenge-text using the configured WEP key and sends it back in another authentication ...
Definition. A nonce is an arbitrary number used only once in a cryptographic communication, in the spirit of a nonce word. They are often random or pseudo-random numbers. Many nonces also include a timestamp to ensure exact timeliness, though this requires clock synchronisation between organisations. The addition of a client nonce (" cnonce ...
Rotor machine. In cryptography, a rotor machine is an electro-mechanical stream cipher device used for encrypting and decrypting messages. Rotor machines were the cryptographic state-of-the-art for much of the 20th century; they were in widespread use in the 1920s–1970s. The most famous example is the German Enigma machine, the output of ...
Public-key cryptography. An unpredictable (typically large and random) number is used to begin generation of an acceptable pair of keys suitable for use by an asymmetric key algorithm. In an asymmetric key encryption scheme, anyone can encrypt messages using a public key, but only the holder of the paired private key can decrypt such a message.
A cryptographic hash function ( CHF) is a hash algorithm (a map of an arbitrary binary string to a binary string with a fixed size of bits) that has special properties desirable for a cryptographic application: [ 1] finding an input string that matches a given hash value (a pre-image) is unfeasible, assuming all input strings are equally likely.