Shhark started as a fork of bark-web from @secondhq. I’m building on that foundation with private messaging, Ark-signed contact cards, and experimental P2P Payjoin.

The idea is to exchange payment details and transaction proposals through a private connection inside your wallet. Shhark’s direct mode connects approved contacts over Tor onion services, hiding their IP addresses from each other.

Three pieces bring this together:

Ark-signed contact cards bind shared details and receiving addresses to a specific recipient and network. They prove control of the signing address, not someone’s real-world identity.

Hybrid post-quantum encryption combines ML-KEM-768 and X25519 to protect messages against future quantum decryption. Identity and Bitcoin transaction signatures remain classical.

Direct P2P Payjoin exchanges proposals through that authenticated messaging channel, without a Payjoin directory or automatic relay fallback. Both peers need compatible Shhark builds.

The signatures and encryption serve different purposes. Sharing a signed contact card doesn’t authorize a payment; transaction approvals remain separate.

A couple of limits: your self-hosted Shhark server handles message encryption and decryption, so it remains a trusted endpoint. The Ark boarding variant substitutes the receiving output without adding receiver inputs, so it doesn’t promise the usual Payjoin anonymity benefit.

This is experimental work under integration testing, without a completed security audit or production qualification.

Credit to Second for bark-web and Bark. Feedback on contact verification, Tor Stores, offline recovery, messaging, and the direct Payjoin design would be welcome.

Shhark source (https://gitlab.com/PiHiker/shhark)
P2P Payjoin details (https://gitlab.com/PiHiker/shhark/-/tree/shhark-main/payjoin/direct)