Beside the standard authentication service on GUARDIAN systems (which is based on static passwords), the authentication service $AS offers an additional method:

  • Challenge/Response and
  • TimeToken

Authentication, based on Atalla and Vasco Challenge/Response Devices.
It is intended to be used by customer applications, such as PATHWAY applications, as well as GHS products.


  • The $AS system is monitored by a PATHMON process pair, due to availability reasons.
    ANY running PATHMON can be used.
  • It runs as a server class: The PATHMON in charge of $AS is responsible for starting/re-starting the service.
  • The $AS process can be reached through PATHSEND, or directly with OPEN/WRITEREAD/CLOSE procedures.
  • $AS process supports the following messages:
    - Generate a random number
    - Check a Challenge/Response number pair
    - Check a TimeToken
    - Authentication Request (initialization)
    - Authentication (finalization)
    - Return statistical information
  • INITACR, a block mode program to initialize Atalla (or compatible) Challenge/Response Token.
  • ASCOM, (Authentication Server Command Interpreter) allowing the management of the $AS system.

Additional $AS features

  • After three consecutive failed checks, the requesting process is delayed for a configurable time. This prevents an exhaustive search for a valid Challenge/Response Number Pair.
  • $AS is developed and compiled on an S-Series system, running G06.

This design allows the $AS to become the central authentication service on a Tandem system, even on a network of Tandem systems!

Download product information of $AS (Authentication Server)

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