Yes. I have toyed with js-libp2p to obtain "providers" based on a key, but I believe the part of js-libp2p that allows you to participate in the DHT isn't quite done [0]. I imagine you'd make a CID that would be a simple hash of some shared string. Then you'd tell the network you are a "provider" with that CID, and when requested, you give the offer (AES'd w/ shared string or other shared secret?). The client can just connect to the same DHT and give the hash and get the (encrypted?) offer. Not sure if IPFS has a way for me to prevent other people from serving/replicating the CID I am serving instead of forcing it to be a hash of the content. A similar approach can happen on BT mainline w/ an infohash maybe.