"c/o" functionality [onion layered encrypted MITM forwarding on behalf of others]

A snailmail letter can be sent “care of” someone: Alice sends a letter addressed to

Bob
c/o Caroline
[Caroline’s address]

Caroline gets the letter delivered to her and passes it on to Bob.

Could I permit some of my contacts to send messages c/o me? I would not be able to decrypt anything except the destination address and perhaps a requested delay; I’d just unwrap and forward the message automatically, onion-style.

This would allow two people to talk to one another without disclosing the fact that they are talking to one another, even if they are both forced to use a relay hosted by an adversary.

DC is aimed at trusted friends and family, so this seems to fit.

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