1. Authentication
Ref: Mark Stamp’s “Information Security, Principles & Practice”

2. Authentication Methods
Authentication: determining if user is allowed to access particular resource or not
Problem: authenticating human to a machine
Approaches:
Something you know (Passwords)
Something you have (ATM or smart cards)
Something you are (Biometrics)
Ref: Mark Stamp’s “Information Security, Principles & Practice”

3. Password Based Authentication
An ideal password is
something that you know
something that a computer can verify that you know
something nobody else can guess, even with unlimited computing resources
In practice it is difficult to even come close to this ideal
Ref: Mark Stamp’s “Information Security, Principles & Practice”

4. Passwords
Reasons:
Users tend to select bad passwords (dictionary words)
what if you forget them? - Many things can act as passwords (your PIN number, mother median name, birth date etc…)
passwords are not completely random (how to remember them??????)
Ref: Mark Stamp’s “Information Security, Principles & Practice”

5. Solution choose GOOD Passwords
Make strategy which guides user while creating passwords
Frank
Pikachu
251019
AustinStamp
jfIej(43j-EmmL+Y
P0kem0N
FSa7Yago
Ref: Mark Stamp’s “Information Security, Principles & Practice”

6. A Good Password

8. Solution Make strategy which guides user while creating passwords
Reactive password checking
The system runs its password cracker to find guessable passwords
The system cancels passwords that are guessed and notifies user
Consumes resources
Can be misused by Hackers
Proactive password checking
The system checks if the password is allowable at the time of selection
With guidance from the system, users can select memorable passwords that are difficult to guess
Ref: Mark Stamp’s “Information Security, Principles & Practice”

9. Password Verification
how are the passwords verified by system?
System must have password to compare it with users entry
store the table with user ID and password
Ref: Mark Stamp’s “Information Security, Principles & Practice”

10. Classical Method

11. Password Verification
how are the passwords verified by system?
Storing bare passwords is bad idea
Why not use HASH?
Many systems stores hashed passwords
Every time the entered password is hashed and the value is checked with the stored hash value

12. Hashing the Password

13. Salting Password

14. Biometrics- you are your key
Properties, any biometric should pose:
Universal
Distinguishing
Permanent
Collectable
Reliable, robust & user-friendly
Used for two purpose:
Identification – one to many mapping
Authentication – one to one mapping
Ref: Mark Stamp’s “Information Security, Principles & Practice”

15. Metric for Biometric Phases
Enrollment phase
Recognition phase
Two types of errors that decides the performance
Fraud rate
The rate of miss-authentication
Insult rate
The rate of non-recognition
Ref: Mark Stamp’s “Information Security, Principles & Practice”

16. Types of Biometric in use
Fingerprints
Hand Geometry
Iris Scan
DNA
Face
Voice
Retina
Ref: Mark Stamp’s “Information Security, Principles & Practice”

17. Examples of Galton’s minutia
Fingerprints
Loops (double) Whorl Arch
Examples of Galton’s minutia
Minutia Comparison
Ref: Mark Stamp’s “Information Security, Principles & Practice”

18. Hand Geometry
Ref: Ross, Arun, Anil Jain, and S. Pankati. "A prototype hand geometry-based verification system." Proceedings of 2nd conference on audio and video based biometric person authentication
Ref: Mark Stamp’s “Information Security, Principles & Practice”

19. Iris Scanning
Uses image processing techniques such as digital negative, wavelet transforms to find the iris codes
These codes are then matched during verification
Ref: Mark Stamp’s “Information Security, Principles & Practice”

20. NatGeo’s IRIS Scanning Story

21. NatGeo’s IRIS Scanning Story

22. Something you have
A card that has some amount of memory and computing resources
It can store some cryptographic keys and could do some computations
what if the card goes in wrong hands?
Two factor authentication can be the solution

23. To Conclude Authentication of a human to a machine is based on
something you know
something you have
something you are
passwords are a very unsatisfactory method of
authentication
Biometrics potentially offer much greater security. But, they cost money, and are not without problems
With smartcards we need to be very careful and it needs two factor authentication

24. Brainstorming Compare passwords, Biometrics and smartcards.
Discuss why passwords are more popular as compared to other two secure methods?

25. Token Based Authentication
The best way to handle authentication for multiple users to web applications
Token: random number, question, challenge
Applications:
Facebook
Twitter
Google+
GitHub

26. Server based Authentication
Traditional Method
Stateful service

27. Disadvantages of Server based Authentication
Sessions
Scalability
CORS (cross origin resource sharing)
CSRF (cross site request forgery)

28. How Tokens work? Stateless: No session information
Typical implementation
User Requests Access with Username / Password
Application validates credentials
Application provides a signed token to the client
Client stores that token and sends it along with every request
Server verifies token and responds with data

29. Token based Authentication

30. Token Based Authentication Advantages
Saves memory space
Stateless server configurations
Scalability
Easy passing the authentication
Extra Security

31. Digital Certificates
Ref: William Stallings “Cryptography and Network Security”, 4th Edition

32. Typical Encryption Scenario
Alice
Bob
Alice encrypt her message with Bob’s public key
Bob decrypts Alice’s message with his own private key

33. Typical Digital Signature Scenario
Alice
Bob
Alice encrypt her sign with private key
Alice sends Digital Signature to Bob with her message
Bob verify Alice’s signature with her public key.

34. What is Digital Certificate?
A public key and user's identity bound together
signed by someone called a Certificate Authority (CA), certifying the accuracy of the binding
CA can be an integrated or Individual Entity
It maintains the directory server
Server works only as a distributor
No authority to create the certificates
provides easy access of certificates to the users

35. Digital Certificate Format

36. Digital Certificates A certificate is public information.
Certificates are distributed by means of directories, public folders, and Web pages.
Because the certificate owner's public key is contained in a certificate, distributing a certificate also distributes the public key.
Others can choose to trust a certificate owner's private key based on the reputation of the CA that issued the certificate and based on confidence in the certificate issuing practices of the CA.

37. Certificate Authority Provider

38. X.509 Directory Services

39. X.509 ITU-T recommended Directory Standard
A part of X.500 series of recommendation for dictionary services
Issued in 1988 followed by many versions,
1993
1995
2000

40. X.509 Directory = Repository of public key certificates
Defines a framework for authentication services (certificate structure, authentication protocols)
S/MIME (Secure/Multipurpose Internet Mail Extensions), IP security, SSL (Secure Socket Layer)/TLS (Transport Layer Security), SET (Secure Electronic Transactions) are users of X.509

41. X.509 Format

42. X.509 Fields
Version: Differentiates among successive versions of the certificate format, the default is version 1.
Serial number: An integer value, unique within the issuing CA, that is unambiguously associated with this certificate.
Signature algorithm identifier: The algorithm used to sign the certificate, together with any associated parameters.
Publisher name: X.500 name of the CA that created and signed this certificate.

43. X.509 Fields
Validity Period: Consists of the first and last on which the certificate is valid.
Entity name: The name of the user to whom this certificate refers.
Entity’s public-key information: The public key of the subject, plus an identifier of the algorithm for which this key is to be used
Unique publisher identifier: An optional bit string field used to identify the issuing CA

44. X.509 Fields
Unique Entity identifier: An optional bit string field used to identify uniquely the subject
Additions/Extensions: A set of one or more extension fields.
Signature: Covers all of the other fields of the certificate; it contains the hash code of the other fields, encrypted with the CA's private key. This field includes the signature algorithm identifier.

45. Revise What is a Digital Certificate? What is a Directory ?
What is a role of Directory server?
What is CA?
What is X.509 standard?

46. Public Key Infrastructure (PKI)
Ref:
William Stallings “Cryptography and Network Security”, 4th Edition
Mark Stamp’s “Information Security, Principles & Practice”

47. What is PKI?
Set of hardware, software, people, policies, and procedures needed to create, manage, store, distribute, and revoke digital certificates based on asymmetric cryptography.
Objective: to enable secure, convenient and efficient acquisition of public keys.

48. Elements of PKI Key generation & management
Digital Signatures
PKC Algorithms
Digital Certificates
Certificate Authorities (CAs)
Dictionary Server
Dictionary Services
Certificate Revocation Lists (CRLs)
Certificate Revocation Server
Key Archival Server

49. Typical PKI Functions
Registration: The process of enrolling in a PKI. Registration usually involves some offline or online procedure for mutual authentication.
Initialization: Before a client system can operate securely, it is necessary to install key materials that have the appropriate relationship with keys stored elsewhere in the infrastructure.
Certification: This is the process in which a CA issues a certificate for a user's public key, and returns that certificate to the user's client system and/or posts that certificate in a repository.

50. Typical PKI Functions
Key pair recovery: Loss of access to the key can result from forgotten passwords/PINs, corrupted disk drives, damage to hardware tokens, and so on. Key pair recovery allows end entities to restore their encryption/decryption key pair from an authorized key backup facility
Revocation request: An authorized person advises a CA of an abnormal situation requiring certificate revocation. Reasons for revocation include private key compromise, change in affiliation, and name change.

51. Typical PKI Functions
Key pair update: All key pairs need to be updated regularly and new certificates issued. Update is required when the certificate lifetime expires and as a result of certificate revocation.
Cross certification: Two CAs exchange information used in establishing a cross-certificate. A cross-certificate is a certificate issued by one CA to another CA that contains a CA signature key used for issuing certificates.

52. Needham-Schroeder Authentication Protocol
Ref:

53. Types The Needham–Schroeder Symmetric Key Protocol
The Needham–Schroeder Public-Key Protocol

54. Needham–Schroeder Symmetric Key Protocol
Alice (A) initiates the communication to Bob (B).
S is a server trusted by both parties
Kas: symmetric key known only to A and S
Kbs: symmetric key known only to B and S
NA and NB are nonce (numbers used once) generated by A and B respectively
Kab: a symmetric, generated key, which will be the session key of the session between A and B

55. Needham–Schroeder Protocol
Alice sends a message to the server identifying herself and Bob, telling the server she wants to communicate with Bob.

56. Needham–Schroeder Protocol

57. Needham–Schroeder Protocol
Alice forwards the key to Bob who can decrypt it with the key he shares with the server, thus authenticating the data.

58. Needham–Schroeder Protocol
Alice performs a simple operation on the nonce, re-encrypts it and sends it back verifying that she is still alive and that she holds the key.

59. N-S Protocol is Vulnerable
Replay Attack
No timestamps
Man in the middle Attack
Server bypassing

60. TEST QUESTIONS
Find public and private key using RSA algorithm: P=7, Q=11, e=13, use Euclid’s Algorithm. Encrypt and Decrypt the message m=3.
Bob has a private key (37, 77) and public key (13, 77). He needs to authenticate any message from him using a signature (of course digital). He chose his sign as ‘5’. Find what will be his Digital signature. How will Alice find that the message is authenticate?
Alice and Bob agrees on q=23 and α=7. Alice chooses secret key as 3 and Bob chooses as 6. Find their public and private keys. Also find the value of common key for Diffie Hellman exchange.
Bob and Alice want to use knapsack for their secure communication. Bob has a Super increasing knapsack [7, 11, 19, 39, 79, 157, 313, 547] and he chooses n=900 and r=37. Calculate the public and private keys of Bob. What is the cipher text if Alice wants to send ‘P’ to Bob. Note: ASCII equivalent of ‘P’ is (50)16
Find public and private key using RSA algorithm: P=17, Q=11, e=7, use Euclid’s Algorithm. Encrypt and Decrypt the message m=4.
Given modulus N=143 and Public key=7, Find the values of p, q, ∅(n) and private key d.
Find public and private key using RSA algorithm: P=11, Q=3, e=3, use Euclid’s Algorithm. Encrypt and Decrypt the message m=15.

61. A real world security protocol
KERBEROS
A real world security protocol

62. What is Kerberos?
KERBEROS: As per Greek Mythology, a three headed Dog to guard the Entrance
Symmetric key based Network authentication protocol
Developed at MIT in the mid 1980s
Available as open source or in supported commercial format

63. Why Kerberos?
Sending usernames and passwords in the clear jeopardizes the security of the network
Use only N symmetric keys for N users.
Simple to implement with no PKI infrastructure

64. Design Requirements
Interactions between hosts and clients should be encrypted.
Must be convenient for users (or they won’t use it).
Protection against intercepted credentials.

65. Cryptography Approach
Private Key: Each party uses the same secret key to encode and decode messages
Uses a trusted third party (ttp) which can vouch for the identity of both parties in a transaction
Security of third party is imperative/vital/crucial.

66. How does Kerberos work?
Instead of client sending password to application server:
Request Ticket from authentication server
Ticket and encrypted request sent to application server
How to request tickets without repeatedly sending credentials?
Ticket granting ticket (TGT)

67. Entities of Kerberos
Authentication Server (AS) OR Key Distribution Center (KDC)
knows all the keys, users and services in the network , Shares unique keys with each user and services
It has a master key called KKDC , known only to KDC
Clients
Service Servers

68. How does Kerberos work? Kerberos Login
The key KA is derived from Alice’s password as
KA = h(Alice’s password)
The KDC creates the session key SA
Alice’s computer decrypts using KA to obtain SA
and the TGT
TGT = E(“Alice”, SA ;KKDC)

69. How does Kerberos work? Kerberos Tickets
REQUEST = (TGT, authenticator)
authenticator = E(timestamp; SA)
REPLY = E(“Bob”, KAB , ticket to Bob; SA)
ticket to Bob = E(“Alice”, KAB ;KB)
Talk to Bob
I want to
talk to Bob
REQUEST
Alice Computer KDC
REPLY
REPLY

70. How does Kerberos work? Granting the Service
Alice can securely talk to Bob now
She sends “ticket to Bob and authenticator” to Bob first
Authenticator= e(timestamp, KAB)
Bob can obtain KAB from ‘ticket to Bob’
Alice & Bob now use KAB for further communication

71. How does Kerberos work? Ticket Granting Tickets

72. How does Kerberos Work?: The Ticket Granting Service

73. How does Kerberos work?: The Application Server

74. Applications Authentication Authorization Confidentiality
Within small sets of networks
How secure is Kerberos?

75. Weaknesses and Solutions
If TGT stolen, can be used to access network services.
Only a problem until ticket expires in a few hours
Subject to dictionary attack
Timestamps require hacker to guess in 5 minutes
Very bad if Authentication Server compromised
Physical protection for the server

76. Single Sign on Systems (SSO)

77. Single Sign on Going to travel Sign in for booking flight ticket
Sign in for booking hotel room
Sign in for renting a car

78. Single Sign on Multi sign on is troublesome
Is it possible to just sign-on once to perform all the actions?
Single sign-on can be used to answer this question.

79. Introduction What is single sign-on (SSO)? Types of SSO.
Two single sign-on system formats:
SAML
Microsoft passport

80. SSO - Definition
Users sign onto a site only once and are given access to one or more applications in a single domain or across multiple domains.
A mechanism to verify a user across multiple applications through a single authentication challenge.
One log-in provides access to all resources of the network, LAN or WAN.

81. SSO - Types Password Synchronization Legacy SSO (Employee SSO) Web SSO
Cross domain (realm) SSO
Federated SSO

82. SSO System - SAML SAML (Security Assertion Markup Language)
an XML framework for exchanging security information over the Internet.
Is based on the concept of Assertions (statements about a user) which can be passed around
Provides a standard request/response protocol for exchanging XML messages

83. Goals of SAML
“Portable Trust” - a user, whose identity is established and verified in one domain, can invoke services in another domain
Cross-Domain Single Sign-On (SSO)
Federated Identity
Web Services - provides a means by which security assertions about messages and service requesters can be exchanged

84. Cross Domain SSO with SAML
A user authenticates to one web site (domain) and then is able to access resources at some other web sites (domains)
A user Joe is authenticated at A.com and can access resources at both A.com and B.com

85. Federated Identity with SAML
A set of service providers agrees on a way to refer to a single user even if he/she is known to each of them under a different name
The user Joe is authenticated at A.com as and can access resources at both B.com and C.com without being re-authenticated

86. SAML Assertions
Assertion : a claim, statement or declaration of fact made by some SAML authority
Types of assertions:
Authentication - the subject was authenticated by a particular means at a particular time
Authorization - the subject was granted or denied access to a specified resource
Attributes - the subject is associated with the supplied attribute

87. Microsoft Passport
Online service that allows secure access to participating Web sites or services
Uses your address as sign name
Uses one password to all Web sites
Allows to make faster, more secure online purchases

88. Microsoft Passport
The information you register with Passport is stored securely in the database
When you sign in to any participating Web sites you use your Passport: login and password
During the Internet session you can sign in to the other Web sites by clicking

89. Participating Web Sites

90. Advantages of SSO Reduced operational cost Reduced time to access data
Improved user experience, no password lists to carry
Advanced security to systems
Ease burden on developers
Centralized management of users, roles.

91. Federated Identity Management

92. What is a Federation?
A group of organizations running IDPs and SPs that agree on a common set of rules and standards
Its a label for people to talk
about such a collection of
organizations
An organization may belong
to more than one federation
at a time
The grouping can be on a regional level or on a smaller scale

93. What is Federated Identity Management?
Federated Identity Management (FIM)
securely shares information managed at a users home organization with remote services.
Within FIM systems it doesn’t matter if the service is in your administrative domain or another.

94. Federated Identity Management
In Federated Identity Management:
Identity Providers (IdP) publish authentication and identity information about users
Service Providers (SP) consume this information and make it available to an application
An IdP or SP is generically known as an entity
The first principle within federated identity management is the active protection of user information
Protect the user’s credentials
only the IdP ever handles the credential
Protect the user’s identity information, including identifier
customized set of information released to each SP

95. Advantages of FIM Reduces work Provides current data
Insulation from service compromises
Minimize attack surface area