Zodl (@zodl_app), a wallet for Zcash (@Zcash) $ZEC, has started rolling out new wallet infrastructure meant to keep network operators from tying a user's IP address to their wallet activity. The update targets a privacy gap that shielded transactions do not close on their own.
The system relies on Oblivious HTTP (OHTTP), an Internet Engineering Task Force (IETF) standard, and enlists Cloudflare and Fastly to operate independent relays.
How the Relay Setup Works
In the new design, wallet requests first pass through relays run by Cloudflare or Fastly. According to TokenPost, a relay can see a user's IP address but cannot read the encrypted wallet request. Zodl's servers then handle the request without the originating IP address, leaving them unable to directly link the request to that address.
As a result, no single party holds both pieces of information. The privacy model is also laid out in the zodl-ohttp repository on GitHub, which describes a path from the wallet to an independent relay, then to an OHTTP gateway and onward to lightwalletd. The relay sees the client IP but not the content, while the gateway sees the content but not the client IP.
OHTTP is defined in RFC 9458, which the IETF published as a Proposed Standard in 2024 January, according to the IETF Datatracker. Fastly's documentation states that its OHTTP relay cannot decrypt the messages it forwards because it does not hold the keys.
Rollout and What Changes for Users
Zodl previously depended on community-operated lightwallet servers, per TokenPost. The new infrastructure is being rolled out gradually on Android and iOS during the week following November 9. F-Droid and GitHub releases are expected later that week, and users will need version 3.20.0.
The change pushes privacy protection down to the network layer. Shielded transactions conceal amounts and addresses on the Zcash blockchain, but a wallet server that sees both a user's IP address and their requests can still piece together a picture of activity. Dividing those two data points between separate parties is designed to close that gap.
The approach has limits. As TechFlow noted, critics on the Zcash Community Forum have pointed out that Cloudflare and Fastly are both US-based companies that must comply with judicial warrants, and they warned that overstating the mechanism could give some users a false sense of security. The same report notes that users who also route traffic through Tor would show a Tor exit node address to the relay rather than their real one.
For Zcash users, the update makes IP-level correlation by the wallet provider harder by default, without requiring manual configuration.
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