Inside Macintosh: Networking /

Chapter 5 - AppleTalk Data Stream Protocol (ADSP)

About ASDSP

This section describes the secure version of ADSP referred to as AppleTalk Secure
Data Stream Protocol (ASDSP). ASDSP is a superset of ADSP that includes authentica-
tion and encryption features. To use ASDSP, you should be familiar with both ADSP
and ASDSP.

ASDSP features allow you to provide users of your application with the ability to exchange encrypted data across a secure session that is established after the users' identities are proven through what is known as the authentication process. Before transmitting the data that a user sends, ASDSP encrypts it and then decrypts the data before delivering it to the application at the remote connection end. Users might want
to identify one another, for example, to verify that a piece of electronic mail came from the sender who claimed to be its author, and they might want to encrypt data that traverses a network if that data is considered confidential or private and they do not want others to intercept and read the data.

To verify the identities of two ends of a connection, an ASDSP application relies on information that is provided by an Apple Open Collaboration Environment (AOCE) authentication server. Your ASDSP client application at the connection end that initiates the session calls the AOCE Authentication Manager to acquire the information necessary for the authentication process from the authentication server, and then it passes this information on to ASDSP.

Note

Because ASDSP is dependent on information from the authentication server, your ASDSP application can only run on systems that also run AOCE and that have access to an AOCE authentication server. If
the AOCE software is installed on the system that runs your application and if the system has access to an AOCE authentication server, your application can use ASDSP.

You perform the first part of the authentication process by requesting information from the authentication server and giving that information to ASDSP to transmit to the other end of the connection. The authentication process culminates in a challenge-and-reply handshake that the ASDSP code performs on behalf of your ASDSP client application
at each end of the connection to ensure that the application users are who they claim to be. The ASDSP client application of the connection end that retrieves the information from the authentication server and makes the request to open the session is called the initiator; the ASDSP client application of the connection end that receives the request and the information from the server is called the recipient.

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Subtopics

The Authentication Process

The Data Encryption Feature