The document discusses stream ciphers and block ciphers, highlighting that stream ciphers encrypt data one byte at a time using a key stream, while block ciphers encrypt data in fixed-size blocks. It explains the function of key streams in stream ciphers and contrasts it with the deterministic approach of block ciphers. Additionally, it humorously notes that the author is not available to answer questions.

1. 1

2. Daffodil International University
SUBMITTED BY
NILOY BISWAS (171-35-225)
TANVIR ISLAM (171-35-239)
Submitted to
RidwanullahYousuf
Lecturer,
Department of SWE
Daffodil International University
2
DATE: 01 April 2019

3. A stream cipher is a symmetric key cipher where each
plain text symbol is encrypted one at a time with the
corresponding key stream to give a symbol of cipher
text stream
 stream cipher
 How does Stream Cipher work?
Unlike block ciphers that operate on chunks of input text,
a stream cipher operates on a byte-at-a-time basis using an
input stream. Actually, a stream cipher works using two
data streams. The second data stream is the stream of key
data. The key data stream is generated by a function whose
seed is the encryption key.
3

4.  stream cipher
Example:
4

5. 5

6. 6

7.  Block cipher
A block cipher is an encryption method
that applies a deterministic algorithm
along with a symmetric key to encrypt
a block of text, rather than encrypting
one bit at a time as in stream ciphers.
7

8.  Example of Block Cipher:
8

9. 9

10. Block Cipher VS Stream cipher
10

11. 11

12. If you have any question… please keep it for yourself. I’m not google!
12