Explanation of Triple-DES

Question

Give a brief explanation of the term Triple-DES.

Answer 1

For some time it has been frequent practice to protect as well as transport a key for DES encryption with the triple-DES. This means that the plaintext is, in consequence, encrypted 3 times.

A number of modes of the triple-encryption have been proposed which are illustrated below:

i) DES-EEE3: Three DES encryptions with the three dissimilar keys.

ii) DES-EDE3: Three DES operations in sequence encrypt-decrypt-encrypt with the three dissimilar keys.

iii) DES-EEE2 and DES-EDE2: Same the pervious formats excluding that the first and third operations employ the same key.