NPTEL-Internetwork Security-Week2-Quiz-2

Question

Q1. Which cipher is commonly used in network-based symmetric cryptographic applications?

 (A) Linear cipher

 (B) Block cipher

 (C) Permutation cipher

 (D) Stream cipher

Answer 1

stream cipher

Answer 2

Answer is both option B) and D).

Types of symmetric-key algorithms

Symmetric-key encryption can use either stream ciphers or block ciphers.^[4]

• Stream ciphers encrypt the digits (typically bytes) of a message one at a time.
• Block ciphers take a number of bits and encrypt them as a single unit, padding the plaintext so that it is a multiple of the block size. Blocks of 64 bits were commonly used. The Advanced Encryption Standard (AES) algorithm approved by NIST in December 2001, and the GCM block cipher mode of operation use 128-bit blocks.

Refer d link below for more information. Wiki says so. :). Yeah!!!

https://en.wikipedia.org/wiki/Symmetric-key_algorithm