PPT Slide

User Org

KDC

User

User Org

AAA Server

Application

TGT

UOST

OK

UOST,

Auth

OK

AM

Figure 7 - Inter-Domain Agent Sequence

User Org Performs Authentication and Authorization

Secure Channel

KDC: Kerberos Key Distribution Center

TGT: Ticket Granting Ticket

UOST: User Org AAA Server Service Ticket

Auth: Authenticator created by User and encrypted with UOST session key

AM: Message authorizing User to Application / Can be bound to:

User name or ID, User IP address (these could be sent in AM), secure channel session between User and Application (if created - would need to pass the session key or identifier to the AAA server)

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Slide Notes and Questions:

• What set of information does the User Org authorization message (AM) contain?

2. What exactly is implied by “secure channel”?

• Are there any security issues?

4. The reason why a secure channel is needed between the Application and the User Org authorization server is

because the AM message is not protected. The secure channel could be removed if AM is sent as a

certificate signed with some shared secret between the Application and the User Org authorization server.

5. UOST => {Tcs}Ks

Tcs => User Org AAA server, User, IP addr of User, ts, lifetime, Kcs

Ks => User Org AAA server’s shared key with the KDC

Auth => {Ac}Kcs

Ac => name of User, IP addr of User, ts (New Ac must be generated per service request)

Kcs => Session key for User and User Org AAA server