UGC NET Computer Science July 2018 - II Question 45

Question 45

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45. Match the following symmetric block ciphers with corresponding block and key sizes : 

List - I	List - II
(a) DES	(i) block size 64 and key size ranges between 32 and 448
(b) IDEA	(ii) block size 64 and key size 64
(c) BLOW FISH	(iii) block size 128 and key sizes 128, 192, 256
(d) AES	(iv) block size 64 and key size 128

Code :

	(a)	(b)	(c)	(d)
(1)	(iv)	(ii)	(i)	(iii)
(2)	(ii)	(iv)	(i)	(iii)
(3)	(ii)	(iv)	(iii)	(i)
(4)	(iv)	(ii)	(iii)	(i)

Answer : (2)

Explanation Question 45

DES:
DES(Data Encryption Standard) is an implementation of a Feistel Cipher. It uses 16 round Feistel structure. The block size is 64-bit. Though, key length is 64-bit, DES has an effective key length of 56 bits, since 8 of the 64 bits of the key are not used by the encryption algorithm (function as check bits only).

IDEA:
International Data Encryption Algorithm (IDEA)
DEA operates on 64-bit blocks using a 128-bit key

BLOW FISH:
- Blowfish Cryptosystem
64-bit block cipher with variable length key. The key length is variable ,it can be in the range of 32~448 bits: default 128 bits key length

AES:
Advanced Encryption Standard
Key sizes :128, 192 or 256 bits
Block sizes: 128 bits

Hence, Correct Match are (a) → (ii), (b) → (iv), (c) → (i), (d) → (iii)

So, option 2 is correct answer

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