Kerckhoffs Institute - design template

1. Kerckhoffs tips Mail info@kerckhoffs-institute.org to register otherwise lecturers at the other universities may not know you Register officially with TU/e, RUN & UT otherwise your marks cannot be transferred Regularly check www.kerckhoffs-institute.org/ otherwise you may not be up to date on the schedules Did you take Algebra & Security as homologation? otherwise you may not be able to pass Cryptography I Join the Kerckhoffs student association Auguste otherwise you will not be able to make friends with all your peers Join the mailing list http://mailman.science.ru.nl/mailman/listinfo/kerckhoffs-students otherwise we will not be able to reach you.

2. Introduction toComputer Security Pieter.Hartel@utwente.nl

3. IntroSec 3 Overview Course organisation Definitions Design Cryptography Security Protocols Coursework

4. Course Organisation

5. IntroSec 5 Course objectives Learn about the most important concepts in computer security Be able to appreciate the role of security techniques in an overall security approach Be able to find, understand and survey basic security literature Breadth, not depth....

6. IntroSec 6 Assessment Written examination (50%) Social Engineering Experiment (25%) Stage I: Physical penetration testing (24%) Stage II: Digital penetration testing (1%) Paper for mini conference (25%) Team of three Peer review Mark set by students and moderator 5 best papers presented at mini conf. Prize for best presentation Exceptionally: Paper + experiment (50%)

7. IntroSec 7 Survey Have you taken any of these? TU/e: Security (3ec/2IS05) RU: Security (3ec/I00086 or 6ec/IBI002) UT: Network security (5ec/265400) Something else that is relevant?

8. IntroSec 8 http://dies.cs.utwente.nl/~pieter/IntroSec Twente: differentTwente: different

9. Definitions

10. IntroSec 10 Security is protection of assets. Talk about the bullets in the order given by the subscripts; There is a loop! Attack is malicious external fault, internal fault is vulnerabilityTalk about the bullets in the order given by the subscripts; There is a loop! Attack is malicious external fault, internal fault is vulnerability

11. IntroSec 11 Definitions Availability: authorised users want the computer/system to work as they expect it to, when they expect it to Reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time Safety: being protected against non-desirable events (not specifically malicious) Confidentiality: to stop unauthorised users from reading sensitive information Integrity: Every data item/system component is as the last authorised modifier left it Maintainability: ease with which a software product can be modified Authorisation requires authentication and audit!

12. IntroSec 12 Dependability vs. Security

13. IntroSec 13 Access control model � AU3 Authentication: determine who makes request Authorisation: determine who is trusted to do which operation on an object Auditing: make it possible to determine what happened and why

14. IntroSec 14 Privacy vs. Security Privacy is the right of an individual to determine what information about oneself to share with others Security can help Selectively encrypt data Security can hinder Calling home to prevent piracy (Audit) logging

15. Design

16. IntroSec 16 Goals Good: As secure as the real world [Lam04] Defense in depth Be explicit about: naming, typing, freshness, assumptions, goals, limitations etc [And95a] Bad: Design security as an afterthought Security by obscurity [Ker1883] Make it complicated Defense in dept: firewall+sandbox+application-level checking Money talks, though. Many companies have learned that although people may complain about inadequate security, they won�t spend much money, sacrifice many features, or put up with much inconvenience to improve it. This strongly suggests that bad security is not really costing them much. Firewalls and antivirus programs are the only really successful security products, and they are carefully designed to require no end user setup and to interfere very little with daily life. The experience of the past few years confirms this analysis. Virus attacks have increased, and people are now more likely to buy a firewall and antivirus software and to install patches that fix security flaws. Vendors are making their systems more secure, at some cost in backward compatibility and user convenience. But the changes have not been dramatic. Defense in dept: firewall+sandbox+application-level checking Money talks, though. Many companies have learned that although people may complain about inadequate security, they won�t spend much money, sacrifice many features, or put up with much inconvenience to improve it. This strongly suggests that bad security is not really costing them much. Firewalls and antivirus programs are the only really successful security products, and they are carefully designed to require no end user setup and to interfere very little with daily life. The experience of the past few years confirms this analysis. Virus attacks have increased, and people are now more likely to buy a firewall and antivirus software and to install patches that fix security flaws. Vendors are making their systems more secure, at some cost in backward compatibility and user convenience. But the changes have not been dramatic.

17. IntroSec 17 Tools Assurance � does it work? Risk management Protocol verification Policy � what is supposed to happen? Access control Mechanisms � how should it happen? Tamper resistance Biometrics Cryptography, Hashing, Random numbers But first an attack...

18. IntroSec 18 Attacks Definition: a successful exploitation of a vulnerability Examples: Attacker shuts you out by trying to log in as you Cold boot attack (watch the movie)

19. Cryptography Twente: One slide each on Symmetric Ciphers Asymmetric Ciphers HashingTwente: One slide each on Symmetric Ciphers Asymmetric Ciphers Hashing

20. IntroSec 20 Algorithms + keys Cipher (aka cryptosystem) �Public� algorithm + Secret keys �Public�: discussion Keys must be the same�Public�: discussion Keys must be the same

21. IntroSec 21 Symmetric ciphers Public algorithm + one secret key Standard algorithms: DES, AES Example: one time pad �Public�: discussion Keys must be the same�Public�: discussion Keys must be the same

22. IntroSec 22 Asymmetric ciphers Public algorithm+private key+public key Standard algoritms: RSA, El Gamal Example: El Gamal Multiplicative group Zn*={1...n-1} Prime n, generator g Private key: x ? Zn* Public key: h = gx Salt: y?RZn* Enc(m,h): (c,d) = (mhy, gy) Dec((c,d),x): c/dx Exercise: prove that this works... g is a generator of Zn* if all elements of Zn* can be expressed as g^i for some i c/gy^x=m.g^x^y/g^y^x=m 2.113 Definition The integers modulo n, denoted Zn, is the set of (equivalence classes of) integers {0,1,2, ... , n-1}. Addition, subtraction, and multiplication in Zn are performed modulo n. 2.124 Definition The multiplicative group of Zn is Zn* = { a (- Zn | gcd(a, n) = 1 } In particular, if n is a prime, then Zn* = { a | 1 <= a <= n - 1} g is a generator of Zn* if all elements of Zn* can be expressed as g^i for some i c/gy^x=m.g^x^y/g^y^x=m 2.113 Definition The integers modulo n, denoted Zn, is the set of (equivalence classes of) integers {0,1,2, ... , n-1}. Addition, subtraction, and multiplication in Zn are performed modulo n. 2.124 Definition The multiplicative group of Zn is Zn* = { a (- Zn | gcd(a, n) = 1 } In particular, if n is a prime, then Zn* = { a | 1 <= a <= n - 1}

23. IntroSec 23 Random numbers Pseudo random in SW True random in HW Standard statistical tests NIST web site For example Linear Congruential Method r0 = s rn+1=(a rn+c) mod m Cyclic ? Deterministic ? 0 < m modulus 0 <= a < m multiplier 0 <= c < m increment 0 <= X0 < m seed 0 < m modulus 0 <= a < m multiplier 0 <= c < m increment 0 <= X0 < m seed

24. IntroSec 24 Hash functions Map arbitrary bit string to fixed size output Easy to calculate for given input Practically impossible to invert Extremely unlikely that two inputs give the same hash For example Knuth�s variant on Division Hash(n) = n(n+h) mod m Try it out�

25. IntroSec 25 Visual Cryptography

26. Security Protocols

27. IntroSec 27 Definitions Sequence of communications by two or more parties to achieve security objective(s) Not like this:

28. IntroSec 28 Eve can: See all messages Delete, alter, inject and redirect messages Initiate new communications Reuse messages from past sessions Eve cannot: Solve �hard� problems Guess pseudo-random values (eg. nonces) Get another identity (identity theft) Time computations What to do: Make everything explicit Dolev Yao attacker model

29. IntroSec 29 Design is hard ��Security protocols are three line programs that people still manage to get wrong�� (Roger Needham)

30. IntroSec 30 Authentication protocol (1) What�s the problem with this? The nonce Nb leaks, so it cannot be used to secure the session

31. IntroSec 31 Authentication protocol (2) (Wo)man in the middle attack:

32. IntroSec 32 Authentication protocol (3) Does it work now?

33. IntroSec 33 Conclusions Consider the system as a whole Know your enemy Be explicit Use standard tools

34. Coursework

35. IntroSec 35 Penetration test Stage I and III : gain possession of a marked notebook on the UT campus by using social engineering. Stage II : capture a number of flags on a remote server by using standard penetration testing tools. Paper : solve a problem and validate the solution.

36. IntroSec 36 Paper topics Ranking Attack Scenarios Ethics in Physical Penetration Testing The Personal Chief Security Officer Efficient Implementation of Searchable Encryption Data-based Access Control Privacy Breach from Inter-OSN Inferences Security and Privacy in Body Sensor Networks Tracking Insiders Presenting Soft Policies Alternate Password Entry Methods for Mobile Devices

37. IntroSec 37 What to do next (1) Constraints pentesting 12 groups at UT only Sorry, not possible in Nijmegen or Eindhoven Constraint group size 3 By Tuesday 31 Aug at noon, send email to trajce.dimkov@utwente.nl First, second and third topic choice Team name Allocation published same day

38. IntroSec 38 What to do next (2) By the end of this class: Choose team, topic & notebook target Sign documents. By the 5th of September: Read the references associated with the topic. Write outline+abstract for the paper. Scout the notebook target. On the 6th of September after lecture: The physical penetration testing exercise starts. Meet with supervisors to discuss the paper. Labwork 2-5pm room Carr� 1175 (bring laptop!)