1 / 15

Cryptography and Network Security

Cryptography and Network Security. Professor Dr. M. Ismail Jabiullah Department of Software Engineering Daffodil International University. Topics. Cryptography Cryptographic Terms Cryptographic Components Encryption/Decryption Types of Cryptographic Algorithms Symmetric Key Cryptography

zeke
Download Presentation

Cryptography and Network Security

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Cryptography and Network Security Professor Dr. M. Ismail Jabiullah Department of Software Engineering Daffodil International University

  2. Topics • Cryptography • Cryptographic Terms • Cryptographic Components • Encryption/Decryption • Types of Cryptographic Algorithms • Symmetric Key Cryptography • Caesar Cipher • Concepts • Problems

  3. 0 1 2 3 4 5 6 7 8 9 10 11 12 A B C D E F G H I J K L M 13 14 15 16 17 18 19 20 21 22 23 24 25 N O P Q R S T U V W X Y Z Text space for writing documents

  4. Plaintext in KKey Algorithm Ciphertext in Ciphertext in Key Algorithm Plaintext in Text Number Number Text ~ Text Number Number Text C 2 K = 4 6 G G 6 K = 4 2 C O 14 18 S S 18 14 O M 12 Forward 16 Q Q 16 Backward 12 M P 15 19 T T 19 15 P U 20 24 Y Y 24 20 U T 19 23 X X 23 19 T E 4 8 I I 8 4 E R 17 21 V V 21 17 R Caesar Cipher Ciphertext : GSQTYXIV Plaintext : COMPUTER

  5. Caesar Cipher Perform the Encryption/decryption operation with key value 5 COME HERE PAY MORE MONEY

  6. Caesar Cipher • Julius Caesar • Process: • Replace each letter of the alphabet with letter standing three places further down the alphabet. • The alphabet is wrapped around, so that the letter following Z is A. • Advantages: • Simply try all possible 25 ways. • Key values are within 25. • Characteristics • The encryption and decryption algorithms are known. • There are only 25 keys to try. • The language of the plaintext is known and easily recognizable.

  7. Caesar Cipher

  8. Cryptography Components • Plaintext • Sender • Receiver • Encryption Algorithm • Ciphertext • Decryption Algorithm

  9. Key Elements Plaintext = P Encryption Algorithm = E Decryption Algorithm = D Ciphertext = C Key = K

  10. Symmetric-key Cryptography Or Single Key Cryptography Private Key Cryptography

  11. Public-key Cryptography Public-key algorithms are more efficient for short messages.

  12. Signing the Whole Document

  13. Cryptography Algorithms in the world are in two types: • Symmetric-key Cryptography Algorithms or • Secret key Cryptography Algorithms or • Single key Cryptography Algorithms • Asymmetric-key Cryptography Algorithms or • Public key Cryptography Algorithms or • Public-Private key Cryptography Algorithms

  14. Problems • Perform Encryption and Decryption for at least 3 plaintext with key values more than 15.

  15. That’s All For Today

More Related