The contract, including support services, is worth $44,412 to the Canberra firm which is on the search for more clients to overcome losses of $3.72 million suffered in the last financial year.
Other customers of Kojensi include Curtin University and defence contractor Northrop Grumman.
archTIS chief executive Daniel Lai said: "As part of its remit, the OAIC conducts activities that require the sharing of sensitive and classified information with other agencies and industry.
"Because Kojensi is accredited by the Attorney-General's department for use with both government and industry, it is an attractive value-for-money solution for the OAIC.
"The contract also confirms archTIS' strategy of supporting clients with their growing information and cyber security needs via the active management of electronic materials being transferred between external and counterpart organisations."
The OAIC is an independent agency within the Attorney-General's portfolio which looks after privacy, freedom of information and government information policy – with responsibilities that include conducting investigations, reviewing decisions, handling complaints, and providing guidance and advice.
archTIS claims Kojensi Gov has a unique security model that enables government agencies to share information and collaborate while meeting regulatory, security and sovereign compliance requirements for classified information up to the Protected level. That means government information of the highest classification.
The platform can be based for both inter-agency and intra-agency collaboration and once one is on a network connected to the platform, one can log in from a Web front-end and start working.