Cryptography involves mathematical techniques for secure communication in the presence of adversaries. There are two main types: secret key cryptography which uses a single key for encryption and decryption, and public key cryptography which uses separate public and private keys. Common cryptographic algorithms discussed include DES, Triple DES, IDEA, and AES, with AES now being the standard due to the insecurity of DES and the slowness of IDEA and Triple DES.

1. CRYPTOGRAPHYPresenting by: J.P.S.M.K

2. What is CryptographyCryptography

3. In a narrow sense

4. Mangling information into apparent unintelligibility

5. Allowing a secret method of un-mangling

6. In a broader sense

7. Mathematical techniques related to information security

8. About secure communication in the presence of adversaries

9. Cryptanalysis

10. The study of methods for obtaining the meaning of encrypted information without accessing the secret information

11. Cryptology

12. Cryptography + cryptanalysisSecurity AttacksPassive attacks

13. Obtain message contents

14. Monitoring traffic flows

15. Active attacks

16. Masquerade of one entity as some other

17. Replay previous messages

18. Modify messages in transmit

19. Add, delete messages

20. Denial of serviceObjectives of Information SecurityConfidentiality (secrecy)

21. Only the sender and intended receiver should be able to understand the contents of the transmitted message

22. Authentication

23. Both the sender and receiver need to confirm the identity of other party involved in the communication

24. Data integrity

25. The content of their communication is not altered, either maliciously or by accident, in transmission.

26. Availability

27. Timely accessibility of data to authorized entities.Objectives of Information SecurityNon-repudiation

28. An entity is prevented from denying its previous commitments or actions

29. Access control