Security and privacy (Part 2)

1. 29 November 2010 Security and privacy(Part 2)

2. Documentation Reminders • Functional Spec • What the program does • Context, uses cases, interfaces (definition, not screen shots) • Revise to reflect reality • User manuals • Document, help screens, tool tips, … • Describe how handled on your website

3. Documentation Reminders (2) • Installation Guide & Administrator Manual • Whatever is needed to get your system up • Including where to find your code or executable • Make NO assumptions, BUT you can point to other documents or web sites (e.g., tell them to download and install a prereq and give them a web site reference) • Assume that the machine that you are running on caught fire …

4. Documentation Reminders (3) • Design document • Overall architecture • Picture • Be specific • Decomposition • Including code file structure • Naming conventions • Interfaces by tool • Database design • Decisions • If you were taking over the project, what would you ask? • Think of possible enhancements and ask yourself if there is enough information to get started

5. ENCRYPTION

6. Security Level of Encrypted Data • Unconditionally Secure • Unlimited resources + unlimited time • Still the plaintext CANNOT be recovered from the ciphertext • Computationally Secure • Cost of breaking a ciphertext exceeds the value of the hidden information • The time taken to break the ciphertext exceeds the useful lifetime of the information

7. Types of Attacks • Ciphertext only • adversary has only ciphertext • goal is to find plaintext, possibly key • Known plaintext • adversary has plaintext and ciphertext • goal is to find key • Chosen plaintext • adversary can get a specific plaintext enciphered • goal is to find key

8. Attack Mechanisms • Brute force • Statistical analysis • Knowledge of natural language • Examples: • All English words have vowels • There are only 2 1-letter words in English • High probability that u follows q • …

9. PRIVATE KEY

10. Caesar Cipher • Substitute the letter 3 ahead for each one • Example: • Et tu, Brute • Hw wx, Euxwh • Quite sufficient for its time • High illiteracy • New idea

11. Simple Caesar cipher through each rotor But rotors shifted at different rates Roller 1 rotated one position after every encryption Roller 2 rotated every 26 times… Enigma Machine(Germany, World War II)

12. Private Key Cryptography • Sender, receiver share common key • Keys may be the same, or trivial to derive from one another • Sometimes called symmetric cryptography or classical cryptography • Two basic types • Transposition ciphers (rearrange bits) • Substitution ciphers • Product ciphers • Combinations of the two basic types

13. DES (Data Encryption Standard) • A block cipher: • encrypts blocks of 64 bits using a 64 bit key • outputs 64 bits of ciphertext • A product cipher • performs both transposition (permutation) and substitution on the bits • Considered weak • Susceptible to brute force attack • http://www.tropsoft.com/strongenc/des.htm

14. Cracking DES • 1998: Electronic Frontier Foundation cracked DES in 56 hrs using a supercomputer • 1999: Distributed.net cracked DES in 22 hrs • With specialized hardware, DES can be cracked in less than an hour.

15. History of DES • IBM develops Lucifer for banking systems (1970’s ) NIST and NSA evaluate and modify Lucifer (1974) • Modified Lucifer adopted as federal standard (1976) • Name changed to Data Encryption Standard (DES) • Defined in FIPS (46-3) and ANSI standard X9.32 • NIST defines Triple DES (3DES) (1999) • Single DES use deprecated - only legacy systems. • NIST approves Advanced Encryption Std. (AES) (2001) • AES (128-bit block) • Attack published in 2009 • Current state of the art is AES-256

16. PUBLIC KEY

17. Public Key Cryptography • Two keys • Private key known only to individual • Public key available to anyone • Public key, private key inverses • Confidentiality • encipher using public key • decipher using private key • Integrity/authentication • encipher using private key • decipher using public one

18. Public Key Requirements • Computationally easy to encipher or decipher a message given the appropriate key • Computationally infeasible to derive the private key from the public key • Computationally infeasible to determine the private key using a chosen plaintext attack

19. RSA • Public key algorithm described in 1977 by Rivest, Shamir, and Adelman • Exponentiation cipher • Relies on the difficulty of factoring a large integer • RSA Labs FAQ document (good intro) http://www.rsasecurity.com/rsalabs/node.asp?id=2152

20. RSA Usage for Encryption • Public key: (n,e); private key: (n,d) • Public key to encipher • Private key to decipher • Encryption • Encipher: c = me mod n • Decipher: m = cd mod n

21. RSA Basics for choosing keys • Choose two large primes p and q • n =pq • Choose e • Less than n • Relatively prime to (p-1)(q-1) • Choose d • (ed-1) divisible by (p-1)(q-1) • Public key: (n,e); private key: (n,d) • A Guide to RSA

22. Summary • Private key (classical) cryptosystems • encipher and decipher using the same key • Public key cryptosystems • encipher and decipher using different keys • computationally infeasible to derive one from the other

23. AUTHENTICATION

24. Authentication • Assurance of the identity of the party that you’re talking to • Primary technologies • Digital Signature • Kerberos

25. Digital Signature • Authenticates origin, contents of message in a manner provable to a disinterested third party (“judge”) • Sender cannot deny having sent message (service is “nonrepudiation”) • Limited to technical proofs • Inability to deny one’s cryptographic key was used to sign • One could claim the cryptographic key was stolen or compromised • Legal proofs, etc., probably required • Protocols based on both public and private key technologies

26. RSA for Digital Signature • Public key: (n,e); private key: (n,d) • Public key to sign • Private key to validate • Digital signature • Sign: s = md mod n; send (s,m) • Validate: m = se mod n

27. Kerberos • Authentication system • Central server plays role of trusted third party • Ticket (credential) • Issuer vouches for identity of requester of service • Authenticator • Identifies sender • User must • Authenticate to the system • Obtain ticket to use server S • Problems • Relies on synchronized clocks • Vulnerable to attack

28. “Using encryption on the Internet is the equivalent of arranging an armored car to deliver credit card information from someone living in a cardboard box to someone living on a park bench” – Gene Spafford (Purdue) NETWORK SECURITY

29. Firewall Techniques • Filtering • Doesn’t allow unauthorized messages through • Can be used for both sending and receiving • Most common method • Proxy • The firewall actually sends and receives the information • Sets up separate sessions and controls what passes in the secure part of the network

30. DMZ: Demilitarized Zone • Arrangement of firewalls to form a buffer or transition environment between networks with different trust levels Fire wall Fire wall Internal resources Internet

31. Fire wall Fire wall Fire wall Internal resources Internet Three Tier DMZ Web Server App Server

32. When you walk into the store, the big-screen displays "Hello Tom," your shopping habits, and other information from Minority Report PRIVACY

33. Some Views on Privacy • “All this secrecy is making life harder, more expensive, dangerous …” Peter Cochran, former head of BT (British Telecom) Research • “You have zero privacy anyway.” Scott McNealy, CEO Sun Microsystems • “By 2010, privacy will become a meaningless concept in western society” Gartner report, 2000

34. Legal Realities of Privacy • Self-regulation approach in US, Japan • Comprehensive laws in Europe, Canada, Australia • European Union • Limits data collection • Requires comprehensive disclosures • Prohibits data export to unsafe countries • Or any country for some types of data

35. Aspects of Privacy • Anonymity • Security • Transparency and Control: knowing what is being collected

36. Privacy and Trust • Right of individuals to determine if, when, how, and to what extent data about themselves will be collected, stored, transmitted, used, and shared with others • Includes • right to browse the Internet or use applications without being tracked unless permission is granted in advanced • right to be left alone • True privacy implies invisibility • Without invisibility, we require trust

37. Technologies • privacy aware technologies (reactive) • non-privacy-related solutions that enable users to protect their privacy • Examples • password and file-access security programs • unsubscribe • encryption • access control • privacy enhancing technologies (proactive) • solutions that help consumers and companies protect their privacy, identity, data and actions • Examples • popup blockers • anonymizers • Internet history clearing tools • anti-spyware software

38. Impediments to Privacy • Surveillance • Data collection and sharing • Cookies • Web site last year was discovered capturing cookies that it retained for 5 years • Sniffing, Snarfing, Snorting • All are forms of capturing packets as they pass through the network • Differ by how much information is captured and what is done with it

39. P3P • Platform for Privacy Preference • World Wide Web Consortium (W3C) project • Voluntary standard still in draft form • Structures a web site’s policies in a machine readable format • Allows browsers to understand the policy and behave according to a user’s defined preferences

40. Privacy and Wireless • “Wardriver” program: scans for broadcast SSIDs • broadcasting improves network access, but at a cost • once the program finds the SSID • obtains the IP address • obtains the MAC address • … • Lowe’s was penetrated this way • Stole credit card numbers