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Glossary of Terms (Page 3) |
Data Encryption Standard - See DES. decryption - The inverse (reverse) of encryption. DES - Data Encryption Standard, a block cipher developed by IBM and the U.S. government in the 1970's as an official standard. See also block cipher. dictionary attack - A brute force attack that tries passwords and or keys from a precompiled list of values. This is often done as a precomputation attack. Diffie-Hellman key exchange - A key exchange protocol allowing the participants to agree on a key over an insecure channel. differential cryptanalysis - A chosen plaintext attack relying on the analysis of the evolution of the differences between two plaintexts. digest - Commonly used to refer to the output of a hash function, e.g. message digest refers to the hash of a message. digital envelope - A key exchange protocol that uses a public-key cryptosystem to encrypt a secret key for a secret-key cryptosystem. digital fingerprint - See digital signature. digital signature - The encryption of a message digest with a private key. digital timestamp - A record mathematically linking a document to a time and date. discrete logarithm - Given two elements d, g, in a group such that there is an integer r satisfying g ** r = d, r is called the discrete logarithm. discrete logarithm problem - The problem of given d and g in a group, to find r such that g ** r = d. For some groups, the discrete log problem is a hard problem that can be used in public-key cryptography. distributed key - A key that is split up into many parts and shared (distributed) among different participants. See also secret sharing. DMS - Defense Messaging Service. DOD - Department of Defense. DSA - Digital Signature Algorithm. DSA is a public-key method based on the discrete log problem. DSS - Digital Signature Standard. DSA is the Digital Signature Standard. ECC - Elliptic Curve Cryptosystem; A public-key cryptosystem based on the properties of elliptic curves. ECDL - See elliptic curve discrete logarithm. EDI - Electronic (business) Data Interchange. electronic commerce (e-commerce) - Business transactions conducted over the Internet. electronic mail (e-mail) - Messages sent electronically form one person to another via the Internet. elliptic curve - The set of points (x,y) satisfying an equation of the form y ** 2 = x ** 3 + ax + b, for variables x, y and constants a, b. elliptic curve cryptosystem - See ECC. elliptic curve discrete logarithm (ECDL) problem - The problem of given two points P and Q on an elliptic curve, to find m satisfying mP = Q, assuming such and m exists. elliptic curve (factoring) method - A special-purpose factoring algorithm that attempts to find a prime factor p of an integer n my finding an elliptic curve shows number of points modulo p is divisible by only small primes. encryption - The transformation of plaintext into an apparently less readable form (called ciphertext) through a mathematical process. The ciphertext may be read by anyone who has the key that decrypts (undoes the encryption) the ciphertext. exclusive or - See XOR. exhaustive search - Checking every possibility individually till the right value is found. See also attack. expiration date - Certificates and keys may have a limited lifetime; expiration dates are used to monitor this. exponential function - A function where the variable is in the exponent of some base, for example, b ** N where N is the variable, and b is some constant. export encryption - Encryption, in any form, which leaves its country of origin. For example, encrypted information or a computer disk holding encryption algorithms that is sent out of the country. |