[gizzlon]

I get that you can expire it, and that helps, but it's not the same as use-once. Of course, just using a timeout is probably fine in many cases, especially if it's used with SSL. But replay attacks are still possible since there's a windows where it can be re-used.

[shaydoc]

Replay attacks are always gonna be possible unless you use a one time token or signature, thems the break's..., unless you wish to get into the something you have and something you know model. How can you do a use once token making concurrent requests without a strong authentication mechanism client side such as issuing private keys to clients....and all the PKI admin overhead. I think its safe to say, that a restful api should be stateless, and bottlenecks such as session state are not necessary.

[gizzlon]

I'll take that as a "yes" ;)

AFAIK, neither signatures or "something you have, know" alone fixes replay attacks. Since this is a well known problem in cryptography, many solutions exists. All of which are probably overkill for this use.

[shaydoc]

At least with the use of a digital signature and nonce you can guarantee that the request hasn't been tampered with!