The three core IETF Token Binding Specifications have been sent to the RFC Editor, which means that their normative content will no longer change. It’s time to move implementations to version 1.0! The abstract of the Token Binding over HTTP specification describes Token Binding as:
This document describes a collection of mechanisms that allow HTTP servers to cryptographically bind security tokens (such as cookies and OAuth tokens) to TLS connections.
We describe both first-party and federated scenarios. In a first-party scenario, an HTTP server is able to cryptographically bind the security tokens it issues to a client, and which the client subsequently returns to the server, to the TLS connection between the client and server. Such bound security tokens are protected from misuse since the server can generally detect if they are replayed inappropriately, e.g., over other TLS connections.
Federated token bindings, on the other hand, allow servers to cryptographically bind security tokens to a TLS connection that the client has with a different server than the one issuing the token.
This document is a companion document to The Token Binding Protocol.
This is a huge step towards cryptographically protecting data structures that had previously been bearer tokens, such as browser cookies, refresh tokens, access tokens, ID Tokens, etc., so that they can only be used by the intended party. Congratulations especially to the editors Andrei Popov, Dirk Balfanz, and Jeff Hodges, as well as the chairs John Bradley and Leif Johansson for getting us to this important milestone!
The three specifications are: