Authentication

Richard E. Smith works for Secure Computing Corporation where he provides consulting services in network security to commercial and government organizations, including the National Security Agency. He has also served as principal systems engineer for military network guard systems and the Sidewinder Internet Firewall. He frequently lectures, writes, and conducts seminars on cryptography and computer security. He holds an M.S. and Ph.D. in computer science from the University of Minnesota and a B.S. in engineering from Boston University. 0201615991AB06252001

Preface.


What This Book Is About.



Who This Book Is For.



Acknowledgments.



1. The Authentication Landscape.


A Very Old Story.



Elements of an Authentication System.



Revised Attacks and Revised Defenses.



Security Strategies.



Authentication in Timesharing Systems.



Passwords Under Attack.



Hashed Passwords.



Attacking the Secret.



Guessing Attacks.



Social Engineering.



Sniffing Attacks.



Sniffing in Software.



Trojan Login.



Van Eck Sniffing.



Authentication Factors.



Judging Attack Prevalence.



Summary Tables.



2. Evolution of Reusable Passwords.


Passwords: Something You Know.



Authentication and Base Secrets.



Cultural Authentication.



Random Secrets.



The Unix Password System.



Attacking the Unix Password File.



The M-209 Hash.



The DES Hash.



Dictionary Attacks.



The Internet WorM.



Resisting Guessing Attacks.



Randomness and Bit Spaces.



Biases in Base Secrets.



Average Attack Space.



Summary Tables.



3. Integrating People.


Roles People Play.



Insiders and Outsiders.



Users and Administrators.



Carriers and Crackers.



Enrolling Users.



Self-Authentication.



Enrollment in Person.



Assigning an Initial Secret.



Random Secret.



Cultural Secret.



Changing the Initial Password.



Entropy and User Password Selection.



Statistical Bias in Text.



Dictionary Attacks.



Estimating Bias in Password Selection.



Restricting Password Selection.



Therapeutic Password Cracking.



Automatic Password Generation.



Proactive Password Checking.



Limitations on Password Strength.



Summary Tables.



4. Design Patterns.


Patterns in Authentication Systems.



The Role of Physical Security.



Protecting Software Authentication.



Protecting Workstations.



Hardware Protection of Authentication.



Administrative Requirements.



Physical Protection.



Ease of Authentication.



Efficient Administration.



Local Authentication.



Direct Authentication.



Indirect Authentication.



Authentication Protocols.



Indirect Authentication Protocols.



Off-Line Authentication.



Applying the Patterns.



Summary Tables.



5. Local Authentication.


Laptops and Workstations.



Workstation Encryption.



File Encryption.



Volume Encryption.



Encryption for Data Protection.



Shortcut Attacks on Encryption.



Trial-and-Error Attacks on Encryption.



Theoretical Guess-Rate Limitations.



Key-Handling Issues.



Memorized Keys.



Key-Handling Policies.



Key Escrow and Crypto Politics.



Summary Tables.



6. Picking PINs and Passwords.


Password Complexity.



Passwords and Usability.



Forcing Functions and Mouse Pads.



Different Secrets for Different Uses.



Sniffable Passwords.



PIN Applications.



Internal Passwords.



External Passwords.



Improving Internal Password Entry.



Operator-Controlled Password Display.



Report Incorrect User Names.



Allow Many Password Guesses.



Report Incorrect Password Attempts.



Avoid Periodic Password Changes.



Password Selection.



Internal Passwords.



External and Administrative Passwords.



Shared Passwords.



Multiple-Use Passwords.



Password Delegation.



Storing Written Passwords.



Physical Custody.



Locked Storage.



Electronic Storage.



Sequences and Groups of Passwords.



Password Sequences.



Forward Secrecy With Theme Words.



Passwords From Songs and Poems.



Summary Tables.



7. Biometrics.


Biometrics: Something You Are.



Promise and Reality.



Uses of Biometrics.



Biometric Techniques.



Measuring Physical Traits.



Measuring Behavioral Traits.



How Biometrics Work.



Taking a Biometric Reading.



Feedback During Biometric Input.



Forging a Physical Trait.



Building and Matching Patterns.



Example: A Trivial Hand Geometry Biometric.



Enrolling a User.



Biometric Accuracy.



Trading Off Usability and Security.



Average Attack Space.



Biometric Encryption.



Preserving Secrecy.



Authenticity of Biometric Data.



The Problem of Biometric Exploitation.



Summary Tables.



8. Authentication by Address.


Who Versus Where.



Telephone Numbers as Addresses.



Identification via Dial-Back.



Dial-Up Identification: Caller ID.



Network Addresses.



Addressing on the ARPANET.



Internet Protocol Addresses.



Attacks on Internet Addresses.



IP Address Theft.



Denial of Service Attacks.



Effective Source Authentication.



Unix Local Network Authentication.



The “Commands”.



Remote Procedure Calls, NFS, and NIS.



Authenticating a Geographical Location.



Summary Tables.



9. Authentication Tokens.


Tokens: Something You Have.



Passive Tokens.



Active Tokens.



Network Password Sniffing.



One-Time Passwords.



Counter-Based One-Time Passwords.



Clock-Based One-Time Passwords.



Attacks on One-Time Passwords.



Man in the Middle Attack.



IP Hijacking.



Incorporating a PIN.



PIN Appended to an External Password.



PIN as an Internal Password.



PIN as Part of the Base Secret.



Enrolling Users.



Summary Tables.



10. Challenge Response Passwords.


Challenge Response.



Challenge Response and X.



S/Key Authentication.



Challenge Response Issues.



User Interaction.



Known Ciphertext Attack on ANSI X9.9.



Password Token Deployment.



Soft Tokens.



Handling Multiple Servers.



Proprietary Implementations.



Evolving Windows Authentication.



LANMAN Hashing.



Attacking the LANMAN Hash.



Plaintext Passwords on Windows.



Windows Challenge Response.



Attacking Windows Challenge Response.



Windows NTLM Authentication.



Attacking the NT Password Database.



Attacking NTLM Challenge Response.



Summary Tables.



11. Indirect Authentication.


Indirect Authentication.



Network Boundary Control.



One-Time Password Products.



LAN Resource Control.



RADIUS Protocol.



A RADIUS Logon.



Protecting RADIUS Messages.



RADIUS Challenge Response.



Encrypted Connections and Windows NT.



Encrypted Connections.



Integrity Protection.



Politics, Encryption, and Technical Choices.



Windows NT Secure Channels.



Secure Channel Keying.



Attacks on Secure Channels.



Computers' Authentication Secrets.



Summary Tables.



12. Kerberos and Windows 2000.


The Key Distribution Center.



Tickets.



Needham-Schroeder.



Kerberos.



The Authentication Server.



Authenticating to a Server.



Ticket-Granting Service.



User and Workstation Authentication.



Workstation Authentication.



Preauthentication.



Ticket Delegation.



Proxiable TGT.



Forwardable TGT.



Realms and Referral Tickets.



Attacking a Kerberos Network.



Intrusion Tolerance.



Clock Synchronization.



Kerberos in Windows 2000.



Master Keys and Workstation Authentication.



Service and Proocol Support.



Summary Tables.



13. Public Keys and Off-Line Authentication.


Public Key Cryptography.



The RSA Public Key Algorithm.



Attacking RSA.



Attacking RSA Keys.



Attacking Digital Signatures.



The Digital Signature Standard.



Challenge Response Revisited.



LOCKOut Fortezza Authentication Protocol.



FIPS 196 Authentication.



Secure Sockets Layer.



Establishing Keys with SSL.



Authentication with Typical SSL.



SSL Client Authentication.



Public Keys and Biometrics.



Summary Tables.



14. Public Key Certificates.


Tying Names to Public Keys.



Certificate Authorities.



Using the Right Certificate.



Creating Certificates.



Certificate Standards.



Certificates and Access Control.



Certificate Authorities.



Proprietors as Certificate Authorities.



Commercial Certificate Authorities.



Public Key Infrastructure.



Centralized Hierarchy.



Authority Lists.



Cross-Certification.



Personal Certification.



Certified by Reputation.



Certified by a Web of Trust.



Certificate Revocation.



Certificate Revocation List.



On-line Revocation.



Timely Certification.



Certificates with Kerberos.



Summary Tables.



15. Private Key Security.


Generating Private Keys.



The Private Key Storage Problem.



Smart Cards and Private Keys.



Off-Card Key Generation.



On-Card Key Generation.



Smart Card Access Control.



PINs.



Biometrics.



Private Keys on Servers.



Novell NetWare: Key Downloading.



Safeword Virtual Smart Card: Data Uploading.



Passwords Revisited.



Summary Tables.



Notes.


Bibliography.


Web and Vendor Resources.


Glossary.


Index. 0201615991T10012001