Notes for October 28, 1998
- Greetings and Felicitations!
- Office hours 3:00-4:00PM today.
- Security lab seminar 1:00-2:00PM in 1131 EU-II. We will talk about ongoing projects!
- Puzzle of the Day
- Intrusion Detection Systems
- Anomaly detectors: look for unusual patterns
- Misuse detectors: look for sequences known to cause problems
- Specification detectors: look for actions outside specifications
- Misuse Detection
- Look for specific patterns that indicate a security violation
- Basis: need a database or ruleset of attack signatures
- Issues: handling log data, correllating logs
- Problems: can't find new attacks
- Specification Detection
- Look for violations of specifications
- Basis: need a representation of specifications
- Issues: similar to misuse detection
- Advantage: can detect attacks you don't know about.
- Ciphers v. Codes
- Attacks: ciphertext-only, known plaintext, known ciphertext
- Classical Ciphers
- monoalphabetic (simple substitution):
f(a) = a + k mod n
- example: Cæsar with k = 3,
RENAISSANCE -> UHQDLVVDQFH
- polyalphabetic: Vigenère,
a + ki mod n
- cryptanalysis: do index of coincidence to see if it's
monoalphabetic or polyalphabetic, then Kasiski method.
- problem: eliminate periodicity of key
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Page last modified on 11/5/98