1. Chapter 14: Representing Identity Dr. Wayne Summers Department of Computer Science Columbus State University Summers_wayne@colstate.edu http://csc.colstate.edu/summers

2. 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. 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. 4 Identity on the Web  Host Identity –Ethernet (MAC) address: 00-07-E9-72-B3-75 –IP address: 192.168.0.3 –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. 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. 6 Anonymity on the Web  Anonymizer – site that hides the origin of the connection (similar to a proxy server)  Pseudo-anonymous remailer – remailer that replaces the originating e-mail address before it forwards the e-mail but keeps the mappings  Cyberpunk (type 1) remailer – strips the header before forwarding  Mixmaster (type 2) remailer- Cyperpunk remailer that only handles enciphered messages and pads messages to a fixed size before sending them