1. Authentication What you know? What you have? What you are?

2. Authentication CSCE 522 - Farkas/Eastman -- Fall 20052 Authentication Allows an entity (a user or a system) to prove its identity to another entity Typically, the entity whose identity is verified reveals knowledge of some secret S to the verifier Strong authentication: the entity reveals knowledge of S to the verifier without revealing S to the verifier

3. Authentication CSCE 522 - Farkas/Eastman -- Fall 20053 Authentication Information Must be securely maintained by the system.

4. Authentication CSCE 522 - Farkas/Eastman -- Fall 20054 Elements of Authentication Person/group/code/system Distinguishing characteristic Proprietor/system owner/administrator Authentication mechanism Access control mechanism

5. Authentication CSCE 522 - Farkas/Eastman -- Fall 20055 Authentication Requirements System must ensure Data exchange is established with addressed peer entity and not with an entity that masquerades or replays previous messages Data source is the one claimed

6. Authentication CSCE 522 - Farkas/Eastman -- Fall 20056 Authentication vs. Identification Identification – Who are you? Authentication – Why should we believe you? Authentication generally follows identification

7. Authentication CSCE 522 - Farkas/Eastman -- Fall 20057 User Authentication What the user knows Password, personal information What the user possesses Physical key, ticket, passport, token, smart card What the user is (biometrics) Fingerprints, voiceprint, signature dynamics

8. Authentication CSCE 522 - Farkas/Eastman -- Fall 20058 Passwords For each user, system stores (user name, F(password)), where F is some transformation (e.g., one-way hash) in a password file When user enters the password, system computes F(password); match provides proof of identity

9. Authentication CSCE 522 - Farkas/Eastman -- Fall 20059 F(password) Password  F(password): easy F(password)  password: hard Password is not stored in the system

10. Authentication CSCE 522 - Farkas/Eastman -- Fall 200510 Vulnerabilities of Passwords Easy to guess or snoop No control on sharing Visible if unencrypted in networks Susceptible for replay attacks if encrypted naively

11. Authentication CSCE 522 - Farkas/Eastman -- Fall 200511 Advantages of Passwords Easy to modify compromised password System well understood by most users Specialized hardware not needed

12. Authentication CSCE 522 - Farkas/Eastman -- Fall 200512 Weak Passwords Bell Labs study (Morris and Thompson, 1979), 3289 passwords were examined Summary: 2831 passwords (86% of the sample) were weak, i.e., either too easy to predict or too short

13. Authentication CSCE 522 - Farkas/Eastman -- Fall 200513 Study Details 15 single ASCII characters 72 two ASCII characters 464 three ASCII characters 477 four ASCII characters 706 five letters (all lower case or all upper case) 605 six letters, all lower case 492 weak passwords (name, dictionary words, etc.)

14. Authentication CSCE 522 - Farkas/Eastman -- Fall 200514 Password Attacks Guessing attack Dictionary attack Social engineering Spoofing attack Other attacks (covered later)

15. Authentication CSCE 522 - Farkas/Eastman -- Fall 200515 Guessing Attack Exploits human tendency to use easy to remember passwords Trial-and-error attack Easy to detect and block (failed logins) Need audit mechanism

16. Authentication CSCE 522 - Farkas/Eastman -- Fall 200516 Dictionary Attack Attack 1: Create dictionary of common words and names and their simple transformations Use these to guess password Attack 2: Usually F is public and so is the password file (encrypted) Compute F(word) for each word in dictionary Find match

17. Authentication CSCE 522 - Farkas/Eastman -- Fall 200517 Social Engineering Attacker asks for password by masquerading as somebody else (not necessarily an authenticated user) May be difficult to detect Protection against social engineering: strict security policy and user education

18. Authentication CSCE 522 - Farkas/Eastman -- Fall 200518 Login Spoofing Create a fake login screen Capture login and password when user attempts to log in Present a fake failed login screen User may not even notice there is a problem

19. Authentication CSCE 522 - Farkas/Eastman -- Fall 200519 Password Defenses Password salt Password management policies Lamport’s scheme One time passwords Time synchronization Challenge response

20. Authentication CSCE 522 - Farkas/Eastman -- Fall 200520 Password Salt Used to make dictionary attack more difficult Salt is a 12 bit number between 0 and 4095 Derived from system clock and the process ID Compute F(password+salt); both salt and F(password+salt) are stored in the password table User: gives password, system finds salt and computes F(password+salt) and checks for match Note: with salt, the same password is computed in 4096 ways

21. Authentication CSCE 522 - Farkas/Eastman -- Fall 200521 Password Management Policies Educate users to make better choices Define rules for good password selection and ask users to follow them Ask or force users to change their password periodically Actively attempt to break user’s passwords and force users to change broken ones Screen password choices

22. Authentication CSCE 522 - Farkas/Eastman -- Fall 200522 Lamport’s scheme Doesn’t require any special hardware System computes F(x),F 2 (x),…, F 100 (x) (this allows 100 logins before password change) System stores user’s name and F 100 (x) User supplies F 99 (x) the first time If the login is correct, system replaces F 100 (x) with F 99 (x) Next login: user supplies F 98 (x) … and so on User calculates F n (x) using a hand-held calculator, a workstation, or other devices

23. Authentication CSCE 522 - Farkas/Eastman -- Fall 200523 One-time Password Use the password exactly once! Often done for initial assigned passwords User must change password before doing anything else

24. Authentication CSCE 522 - Farkas/Eastman -- Fall 200524 Time Synchronized There is a hand-held authenticator It contains an internal clock, a secret key, and a display Display outputs a function of the current time and the key It changes about once per minute User supplies the user id and the display value Host uses the secret key, the function and its clock to calculate the expected output Login is valid if the values match

25. Authentication CSCE 522 - Farkas/Eastman -- Fall 200525 Challenge/Response Work station Host Network  Non-repeating challenges from the host  The device requires a keypad User ID Challenge Response

26. Authentication CSCE 522 - Farkas/Eastman -- Fall 200526 Challenge/Response Problems Key database is extremely sensitive This can be avoided if public key algorithms are used

27. Authentication CSCE 522 - Farkas/Eastman -- Fall 200527 Devices with Personal Identification Number (PIN) Devices are subject to theft Some devices require PIN (something the user knows) PIN is used by the device to authenticate the user

28. Authentication CSCE 522 - Farkas/Eastman -- Fall 200528 Smart Cards Portable devices with a CPU, I/O ports, and some nonvolatile memory Can carry out computation required by public key algorithms and transmit directly to the host Some use biometrics data about the user instead of the PIN

29. Authentication CSCE 522 - Farkas/Eastman -- Fall 200529 Biometrics Fingerprint Retina scan Voice pattern Signature Typing style Hand geometry

30. Authentication CSCE 522 - Farkas/Eastman -- Fall 200530 Problems with Biometrics Expensive Retina scan (min. cost) about $ 2,200 Voice (min. cost) about $ 1,500 Signature (min. cost) about $ 1,000 False readings Retina scan 1/10,000,000+ Signature 1/50 Fingerprint 1/500 Can’t be modified when compromised

31. Authentication CSCE 522 - Farkas/Eastman -- Fall 200531 Errors in Biometrics False rejection rate (FRR) Authorized subject is rejected False acceptance rate (FAR) Unauthorized subject is accepted Crossover error rate (CER) FRR = FAR

32. Authentication CSCE 522 - Farkas/Eastman -- Fall 200532 Two-factor Authentication Require two forms of authentication Password + smart card PIN + hand geometry

33. Authentication CSCE 522 - Farkas/Eastman -- Fall 200533 Wellness Center Identification – SSN Authorization – hand geometry High change of random hands matching Low chance of your friend’s hand matching yours

34. Authentication CSCE 522 - Farkas/Eastman -- Fall 200534 Single Sign-On (SSO) Provide identification and authorization once for a set of related systems VIP limited SSO Kerberos (ker-ber-OUS) Symmetric key cryptosystem Trusted third party (Key Distribution Center (KDC) – a trusted third party

35. Authentication CSCE 522 - Farkas/Eastman -- Fall 200535 Responsibility for Data Data owner (data administrator) Sets policies Data custodian (database administrator) Implements policies Data user (database user) Follows policies

36. Authentication CSCE 522 - Farkas/Eastman -- Fall 200536 Chapter Topic Review Access control Identification and authentication Possible threats Miscellaneous examples