1. Chapter 14: Representing Identity
Dr. Wayne Summers
Department of Computer Science
Columbus State University

2. Representing Identity
Principal - unique entity (ex. File, user)
Identity - specifies a principal (ex. Filename, UID)
Authentication binds a principal to a representation of identity internal to the computer
Principals may be grouped into sets called groups
Role – type of group that ties membership to function

3. Naming and Certificates
Certificate – mechanism for binding cryptographic keys to identifiers
X.509v3 certificates use Distinguished Names: /O=Columbus State University/OU=Computer Science Dept/CN=Wayne Summers
CA authentication policy
describes the level of authentication required to identify the principal to whom the certificate is to be issued
Defines the way in which principals prove their identity
CA issuance policy describes the principals to whom the CA will issue certificates

4. Identity on the Web Host Identity Static & Dynamic Identifiers
Ethernet (MAC) address: E9-72-B3-75
IP address:
Host name: jaring.colstate.edu
Static & Dynamic Identifiers
ARP (maps MAC and IP addresses)
DNS (maps IP addresses and host names)
DHCP – provides a dynamic IP address
NAT (Network Address Translation): router that translates between external and internal (private) addresses (e.g. 10.x.y.z)

5. Identity on the Web State and Cookies
Cookie – token that contains information about the state of a transaction on a network
name and associated value are encoded to represent the state
Expiration field indicates when the cookie is valid
Domain indicates for which domain the cookie is intended
Path restricts the dissemination of the cookie within the domain
Secure field restricts the use of the cookie to over SSL connections only

6. Anonymity on the Web
Anonymizer – site that hides the origin of the connection (similar to a proxy server)
Pseudo-anonymous r er – r er that replaces the originating address before it forwards the but keeps the mappings
Cyberpunk (type 1) r er – strips the header before forwarding
Mixmaster (type 2) r er- Cyperpunk r er that only handles enciphered messages and pads messages to a fixed size before sending them