Securely storing credentials for repeat web service calls

Question

I'm working on a web application for internal use that is driven by many web service requests to another remote server. The internal site maintains its own session, authenticated by username/password credentials that are themselves backed by the web service(i.e. we make a remote authentication call to verify the login to the internal site). The web service requests also require authentication using these same credentials.

We were hoping these web service requests could remain stateless, which means passing the credentials in with every request for authentication. The problem is remembering the credentials to be used(the ones entered during the initial login) in a way that is secure. I'm not aware of any truly safe way to store a password for later re-use - hashing it would sacrifice our ability to use it again. The best we could do would be to encode it in the session scope and hope that no malicious developer will ever try to catch it in a thread dump or something.

Is there a better solution to this that I'm missing? Am I being overly paranoid about the risk of storing an encoded password in memory, or is our approach to this project flawed?

Answer 1

i would suggest to use token based authetication, a token is passed to the user for cheap user verification on the fly. One implementation of this would be to generate a cookie that is passed to the user for session management.

i have not used but you should look at oauth may be example

Answer 2

Ultimately our conclusion was that no, storing user credentials on the server that are re-usable in any way is not safe, so we can't do truly stateless re-authentication on each web service request. We simply had to compromise and preserve a stateful connection that is initiated and stored during the user's initial login.