Question

Explain in detail the differences between steam and block ciphers?

Answer 1

Answer)

The difference between steam and block cipher are as follows:

Block Cipher is defined as a deterministic and computable function of kk-bit keys which means converting the plain text blocks to cipher text blocks. When we encrypt the plain text block with the same key then we will get the same results. So as to encrypt or decrypt the message we don’t use the cipher directly but use it in a mode of operation. The electronic code book mode (ECB) would cut the message in blocks and applies the cipher to every block and provides the output to the resulting block.

The Stream Cipher is defined as a function which can directly map the kk-bit keys and the random length plain texts to cipher text. This is done in such a manner that the prefixes of the plain text to the prefix of the cipher text. Which means we can compute the start of the cipher text before the trailing part of the plain text. Incase if the plain text is repeated then the corresponding cipher text would not be the same. It might differ in that part of the message which will be encrypted in different ways.

Hope this answer helps. :) Happy to help.