security - GAE: best practices for storing secret keys?

Question

Are there any non-terrible ways of storing secret keys for Google App Engine? Or, at least, less terrible than checking them into source control?

question from:https://stackoverflow.com/questions/6501234/gae-best-practices-for-storing-secret-keys

Answer 1

Not exactly an answer:

• If you keep keys in the model, anyone who can deploy can read the keys from the model, and deploy again to cover their tracks. While Google lets you download code (unless you disable this feature), I think it only keeps the latest copy of each numbered version.
• If you keep keys in a not-checked-in config file and disable code downloads, then only people with the keys can successfully deploy, but nobody can read the keys without sneaking a backdoor into the deployment (potentially not that difficult).

At the end of the day, anyone who can deploy can get at the keys, so the question is whether you think the risk is minimized by storing keys in the datastore (which you might make backups of, for example) or on deployer's machines.

A viable alternative might be to combine the two: Store encrypted API keys in the datastore and put the master key in a config file. This has some potentially nice features:

• Attackers need both access to a copy of the datastore and a copy of the config file (and presumably developers don't make backups of the datastore on a laptop and lose it on the train).
• By specifying two keys in the config file, you can do key-rollover (so attackers need a datastore/config of similar age).
• With asymmetric crypto, you can make it possible for developers to add an API key to the datastore without needing to read the others.

Of course, then you're uploading crypto to Google's servers, which may or may not count as "exporting" crypto with the usual legal issues (e.g. what if Google sets up an Asia-Pacific data centre?).