build api for authentication

we need to build an api for authentication of third party systems to provide authorization before they can use our system, the api should be rest service and returns back a token which can be used for specific time it should be perfectly secured to be used for payments systems with banks it should receive post auth request , verifies client-supplied credentials in request and creates access token. This token is returned in response of authentication request. Validity period of token is 24 hours, after token expiration the client must perform authentication procedure again. All subsequent requests must include actual non-expired token in header.