A new Tandem-based application,
A98toB24, functions is installed on the Tandem. Connectivity between the A98
hardware/system system and the Tandem-based Agent is provided by the Telnet
protocol, with the A98 serving as the client-side application and the Tandem
providing the server-side functions.
Whenever the A98 system needs to store an ATM working key
cryptogram within a Base24 system utilizing ACI's Transaction Security System
(Base24/TSS) application, the A98 contacts the Tandem via Telnet and requests a
service defined as A98toB24. This service provides the trigger to initiate the
new Tandem-based application. The A98toB24 service is defined as DYNAMIC. This
allows it to be initiated one-to-many times without pre-configuration of
multiple static windows.
The A98toB24 subsystem obtains all information for its processing
environment from the service definition within the Tandem Telnet Server
definition. This information includes the following:
EMS Event Log Information for Logging Agent's Status Messages
Name of the HSM Interface Module to Use for Processing
The Type of HSM to be Used (Atalla or RACAL)
A TIMEOUT Period Indicates the amount of time to wait for a message from
the A98
The location of the Base24/TSS CSECD file (which contains cryptogram
information)
This information is passed to the A98toB24 service instance via
the standard Tandem TACL startup sequence. As the A98toB24 process (The
Agent) initializes, it logs all copyright, version and initialization
information to the designated EMS log process in fully-tokenized event
messages. The process then issues a prompt to the A98 system consisting of the
following text:
A98toB24 >
The Agent then posts a READ against the socket and waits for a
message to be processed. If a message is not received within the time period
specified via the timeout startup-parameter, the Agent terminates and the
socket is dissolved.
When a message is received by the Agent from the A98, the message
will be authenticated, and then processed. The lexicon for communication
between these two parties must include at least the following information:
ATM Terminal ID
ATM Working Key (encrypted under a key-exchange key)
A response-code field to allow the Agent to notify A98 of any error
conditions
When the Agent receives a valid request message, it will initiate
the following steps:
If utilizing an Atalla HSM:
Format an 11B command to send to the designated HSM.
Issue the 11B command to the HSM and wait for a response
Receive and validate the 21B response
Extract information from the HSM response message
Perform a READ w/LOCK against the CSECD file for the designated ATM
UPDATE the CSECD record with the new cryptogram
Format a response message to the A98 indicating the outcome of all steps
Configuring a Racal or other HSM would be similar to the Atalla
model using the HSM specific command set.
If an error or timeout occurs at any stage, an appropriate error
condition will be noted in the response message sent to the A98. All error
conditions encountered by the Agent will cause the Agent to produce a
diagnostic EMS event message. These messages will allow post-diagnosis of the
problem should a customer report a problem.
The Agent will be a single-threaded process. It will
fully-process each request received from beginning to end before it will
attempt to receive another request from the A98. If a multi-thread environment
is desired, the A98 may open multiple sockets with the Tandem platform, thus
creating multiple paths for simultaneous processing. Once a single Agent thread
completes a request and responds to the A98, it will again go into a listen
mode looking for additional requests. Once a period of time passes (as
indicated by the TIMEOUT startup parameter) without receipt of a new request,
the Agent will shutdown. Additionally, the A98 may issue a DISCONNECT command
to indicate to the Agent that it should shutdown without delay.
For more information about this or any other host
interface, please contact us at: info@trustedsecurity.com
.
Base 24 is a registered trademark of Transaction Systems
Architects, Inc
Related documents:
A98 ISO-8583 Message Formats
(PDF 110kb)
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