TRIPLE DES

Domain	Definition
Computing	Triple DES A product cipher which, like DES, operates on 64-bit data blocks. There are several forms, each of which uses the DES cipher 3 times. Some forms use two 56-bit keys, some use three. The DES "modes of operation" may also be used with triple-DES. (1995-05-11). Source: The Free On-line Dictionary of Computing.
Source: compiled by the editor from various references; see credits.

Specialty Definition: Triple DES

Triple DES (also 3DES) is the encrypt-decrypt-encrypt EDE mode of the Data Encryption Standard (DES) cipher algorithm.

The encryption is done by

C = encrypt_k₃(decrypt_k₂(encrypt_k₁(P))).

with

P ... plaintext

C ... ciphertext

k_i ... key #i

encrypt, decrypt ... DES

Because DES is not a group, using it in EDE mode will increase its key size by a factor 3 (or 2 in the case of k₁ = k₃); in the case of DES this totals to 168 (or 112) bits. If k₁ = k₂ or k₂ = k₃, triple DES is equal to DES.

The use of three steps is essential to prevent meet-in-the-middle attacks. The choice of decryption for the middle step (as opposed to encryption) does not affect the security of the algorithm but instead lets tools that implement triple DES interoperate with legacy single DES tools.

See also:

Data Encryption Standard
Substitution cipher
Cryptology

Frequency of Internet Keywords: TRIPLE DES

Anagrams: TRIPLE DES

Scrabble® Enable2K-Verified Anagrams
	Words within the letters "d-e-e-i-l-p-r-s-t"
	-1 letter: epistler, peltries, perlites, preedits, priested, relisted, reptiles, respited.
	-2 letters: despite, diester, dieters, epistle, leister, pedlers, pelites, pelters, periled, perlite, pestier, pestled, petrels, preedit, preside, reedits, replied, replies, reptile, resiled, resited, respelt, respite, resplit, retiled, retiles, speiled, speired, spelter, spieled, spieler, spiered, spirted, sterile, striped, tripled, triples.
	-3 letters: delist, desert, desire, deters, diesel, dieter.
	Words containing the letters "d-e-e-i-l-p-r-s-t"
	+1 letter: plaistered, splintered.
	+2 letters: interpleads.
	+3 letters: depilatories, disreputable, heteroploids, postdelivery, presidential, proselytised, proselytized, reduplicates, slipstreamed, stepchildren.
	+4 letters: descriptively, disrespectful, fieldstripped, interpleaders, lepidopterans, lepidopterist, lepidopterous, predilections, presterilized, pteridologies, tetraploidies.
	+5 letters: demultiplexers, despiritualize, disrespectable, drapeabilities, electrodeposit, heteroploidies, lepidopterists, polyneuritides, preestablished, presidentially, rehospitalized, superinsulated, unpredictables.
Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro.