Match the following symmetric block ciphers with corresponding block and key…
2018
Match the following symmetric block ciphers with corresponding block and key sizes:
\(\begin{array} {} & \textbf{List-I} & & \textbf{List-II} \\ \text{(a)} & \text{}\text{DES} & \text{(i)} & \text{block size 64 and key size ranges between 32 and 448} \\ \text{(b)} & \text{IDEA} & \text{(ii)} & \text{block size 64 and key size 64} \\ \text{(c)} & \text{BLOW FISH} & \text{(iii)} & \text{block size 128 and key sizes 128, 192, 256} \\ \text{(d)} & \text{AES} & \text{(iv)} & \text{block size 64 and key size 128} \\ \end{array}\)
\(Code:\)
- A.
(a)-(iv); (b)-(ii); (c)-(i); (d)-(iii)
- B.
(a)-(ii); (b)-(iv); (c)-(i); (d)-(iii)
- C.
(a)-(ii); (b)-(iv); (c)-(iii); (d)-(i)
- D.
(a)-(iv); (b)-(ii); (c)-(iii); (d)-(i)
Attempted by 170 students.
Show answer & explanation
Correct answer: B
Correct matching and brief justification: DES → block size 64, key size 64 (56-bit effective); IDEA → block size 64, key size 128; Blowfish → block size 64, key sizes 32–448; AES → block size 128, key sizes 128/192/256.
DES: uses a 64-bit block and a 64-bit key field (of which 8 bits are parity, so the effective key length is 56 bits).
IDEA: uses a 64-bit block and a 128-bit key.
Blowfish: uses a 64-bit block and variable key sizes from 32 up to 448 bits.
AES: uses a 128-bit block and supports key sizes of 128, 192, or 256 bits.
Therefore the correct mapping is: DES → (block 64, key 64), IDEA → (block 64, key 128), Blowfish → (block 64, key 32–448), AES → (block 128, key 128/192/256).
A video solution is available for this question — log in and enroll to watch it.