Network Security & Cryptography
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This document discusses cryptography and its role in information security. It describes different types of security attacks like interception, modification, and fabrication. It also summarizes common security services like confidentiality, authentication, integrity, and different encryption techniques like symmetric key cryptography, public key cryptography, Caesar cipher and RSA algorithm. The document concludes with explanations of firewalls and their technical working as a security measure to monitor and control access between networks.
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Network Security & Cryptography
- 1. 1 Cryptography: An Innovative Technique for Information Security DR. HIMANSHU GUPTA, SENIOR FACULTY MEMBER, AMITY UNIVERSITY, NOIDA, INDIA
- 4. 4 Security Attacks Information source Information destination Interruption • Attack on availability
- 5. 5 Security Attacks Information source Information destination Interception • Attack on confidentiality
- 7. 7 Security Attacks Information source Information destination Fabrication • Attack on authenticity
- 8. 8 Classify Security Attacks passive attacks - eavesdropping on, or monitoring of, transmissions to: obtain message contents, or monitor traffic flows active attacks – modification of data stream to: masquerade of one entity as some other replay previous messages modify messages in transit denial of service
- 9. 9 Security Attacks Release of message contents Traffic analysis • eavesdropping, monitoring transmissions Passive threats
- 11. 11 Security Attacks Masquerade Denial of service • some modification of the data stream Active threats Replay Modification of message contents
- 13. 13 Security Services Confidentiality – protection from passive attacks Authentication – you are who you say you are Integrity – received as sent, no modifications, insertions, shuffling or replays
- 14. 14 Security Services Nonrepudiation – can’t deny a message was sent or received Access Control – ability to limit and control access to host systems and apps Availability – attacks affecting loss or reduction on availability
- 16. 16 Cryptography Cryptography -- from the Greek for “secret writing” -- is the mathematical “scrambling” of data so that only someone with the necessary key can “unscramble” it. Cryptography allows secure transmission of private information over insecure channels (for example packet-switched networks). Cryptography also allows secure storage of sensitive data on any computer.
- 17. 17 The language of cryptography symmetric key crypto: sender, receiver keys identical public-key crypto: encryption key public, decryption key secret (private) plaintext plaintextciphertext K A encryption algorithm decryption algorithm K B
- 20. 20 Secure Communication over Insecure Medium
- 21. 21 Caesar Cipher Technique: A general concept of Cryptography In cryptography, a Caesar cipher, also known as a shift cipher, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a shift of 3, A would be replaced by D, B would become E, and so on. The method is named after Julius Caesar, who used it to communicate with his
- 22. 22 Caesar cipher is to replace each plaintext letter with one a fixed number of places down the alphabet. This example is with a shift of three, so that a B in the plaintext becomes E in the ciphertext. C = P + K, Here K=3
- 23. 23 Example P (Plain Text): AMITY K (Key) = 4 C = P + 4 C (Cipher Text): EQMXC
- 24. 24 RSA Encryption Algorithm For example. make p = 7and q = 13 We then calculate N = 7∗13 = 91 and (p−1)(q−1) = 72 We next select ke relatively prime to 72 and< 72, yielding 5 Finally,we calculate kd such that ke*kd mod 72 = 1, yielding 29 We how have our keys Public key, ke, N = 5, 91 Private key, kd , N = 29, 91 Encrypting the message 69 with the public key results in the cyphertext 62 Cyphertext can be decoded with the private key Public key can be distributed in cleartext to anyone who wants to communicate with holder
- 25. 25 Encryption and Decryption using RSA Asymmetric Cryptography
- 26. 26 What is a Firewall? a choke point of control and monitoring interconnects networks with differing trust imposes restrictions on network services only authorized traffic is allowed auditing and controlling access can implement alarms for abnormal behavior
- 29. 29 Thank You!!!!
- 30. 30 Have A Nice Week!!!