The Aadhaar authentication ecosystem has a provision in which any agency wishing to authenticate the aadhaar hairs of its customers/employees, etc., can contact an existing AUA (Authentication User Agency). Any agency that enters into an agreement with the AAU is defined as sub-AUA. Any agency wishing to become a direct AUA must enter into an agreement with UIDAI. An ASA may enter into a formal contract with auAs. UIDAI contains a number of proposed directives that can be included in the contract between an ASA and an AAU. However, any contract (and, if applicable, terms and conditions) between an ASA and AAU is left to the exclusive discretion of the signatory parties and UIDAI has no obligation to them. Authentication Service Agency (ASA) – ASA is any entity that transmits authentication requirements on behalf of one or more AAAs to the CIDR. The ASA allows intermediaries to mediate. You have a secure connection with the CIDR and forward AAU authentication requests to the CIDR. THE ASA receive the response from CIDR and refer it to the AAU.