With Functional Encryption, would access control between two parties be possible without revealing the entirety of one party's policy to the other? E.g. such that a server would be incapable of discerning anything more about a client's policy (aside from weather the client's requested action is permissible via single Boolean output), and vice versa for the client when checking that the server is first allowed to receive the action request before transmitting it.
A distributed set on nodes (subjects) within a computation graph communicate peer-to-peer (P2P), exchanging messages, services, etc (objects) via an common API. Subjects exchange identities to authenticate each other with some common source of trust, e.g. a Certificate Authority (CA), thereafter establishing a forward secured channel, e.g. via Transport Layer Security (TLS). Through this channel, the two participants should conduct a form of trust negotiation with respect to validating the other participant is authorized to receive or request a given object respectively.
Ideally, in the interest of preventing any information about the computation graph from being leaked, one may wish that policy definitions be obfuscated from the public. For a large dynamic P2P systems, it is perhaps best participants store only their own provisioned policy, as opposed to all policies for whom they are expected to interact with. To be fully decentralized as well, no connection to a third party broker at run time for access arbitration should be used.
Given these requirements, middle ware standards such as DDS Security from OMG fallow a familiar pattern above where participants exchange signed permission documents that prescribe the policy to enforce upon the owner. In essence, a participant's entire hand of cards is revealed to all recipients. To introspect the topology of the inner data bus and its resources, a malicious actor needs only to annex a single identity in order to connect and aggregate policy documents.
I was thinking this relates to Oblivious Transfer (OT), but instead where the verifier gets exactly one policy decision result without without knowing anything about the rest of the policy that was not pertinent to the inquiry.
- What are the current limitations (and capabilities) of Functional Encryption used for access control?
- What paradigm does ABE, KP-ABE and CP-ABE fall into
- Certificate based Access Control for Pub Sub messaging
Side Note & Motivation
I'd like to create a Mandatory Access Control (MAC) plug in for robotic and Industrial IoT (IIoT) middle wares. I've written one before that leverages regular expressions in clear text extensions within a subject's identity certificate. OMG's DDS Security default plugin does this better by decoupling identity and permission documents for handshaking. However, I think we could do even better than its v1.0 plugin by not sharing entire participant policies. Of course one could just provision the permission document into multiple minimalistic documents for each use niche use case, but my thoughts were that perhaps functional encryption could help avoid such quantized bookkeeping.