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NUMBER THEORY

NUMBER THEORY. Chapter 5: Cryptology. Era of Electronic. Electronic communication Electronic Banking. Terminology. Cryptology: Discipline Cryptography: Design & Implementation Cryptoanalysis : Breaking the system. Terminology. Plaintext: secret message

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NUMBER THEORY

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  1. NUMBER THEORY Chapter 5: Cryptology

  2. Era of Electronic • Electronic communication • Electronic Banking

  3. Terminology • Cryptology: Discipline • Cryptography: Design & Implementation • Cryptoanalysis: Breaking the system

  4. Terminology • Plaintext: secret message • Cipher: method to alter the plaintext • Cybertext: message has been altered

  5. Terminology • encryption/enciphering: process • decryption/deciphering: process

  6. Letter ↔ Integer

  7. Character Cipher Caesar cipher

  8. Exercise

  9. How to decipher?

  10. Exercise

  11. Character Cipher Affine transformation

  12. Complete system of residue!

  13. Exercise:

  14. Secure? • Character cipher is not safe

  15. frequency

  16. Block Cipher Vigenere cipher

  17. Ci=Pi+ki

  18. Exercise • Use the key “SECRET”

  19. Block Cipher Digraphic cipher

  20. Numerical equivalent

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