If your app uses OAuth as a means of authentication, you are likely storing users' OAuth tokens in a database. To maintain the secrecy of these tokens, you can use encryption both in transit and at rest. This article shows how SecureDB can encrypt OAuth tokens in a matter of minutes.
CORS is a security mechanism that allows a Web page from one domain to access a resource from a different origin. This article provides an in-depth guide to Cross-Origin Resource Sharing (CORS) for REST APIs, on how CORS works, and common pitfalls especially around security.