Message can be sent more securely using DES by a. encrypting plain text by a different randomly selected key for each transmission b. encrypting plain text by a different random key for each message transmission and sending the key to the receiver using a public key system c. using an algorithm to implement DES instead of using hardware d. designing DES with high security and not publicizing algorithm used by it  

1 Answer

Answer :

b. encrypting plain text by a different random key for each message transmission and sending the key to the receiver using a public key system

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Description : DES and public key algorithm are combined (i) to speed up encrypted message transmission (ii)to ensure higher security by using different key for each transmission (iii) as a combination is always better than individual system (iv ... e-Commerce a. i and ii b. ii and iii c. iii and iv d. i and iv  

Last Answer : a. i and ii

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Last Answer : b. Working on 64-bit blocks of plain text and 56 bit keys by applying DES algorithm for three rounds. 

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Last Answer : b. guarantees excellent security  

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Last Answer : c. i and iii 

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Last Answer : a. permutation and substitution on 64 bit blocks of plain text 

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Last Answer : d. using digital Signature system 

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Last Answer : a. Cannot be broken in reasonable time using presently available computers.  

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Last Answer : c. public keys of subscribers  

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