Crypto Privacy Tools Hide What You Do in chainbut identifying information may still be leaked around this activity off-chain. The good news, however, is that this weak point is getting more and more attention from the industry lately.
For example, this week the team behind Zodl (the Zcash wallet formerly known as Zashi) has started migrating users to its own wallet servers, designed so that your IP address and your wallet requests never end up in the hands of the same operator. It comes with Zodl 3.20.0 and requires no additional configuration.
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It’s an encouraging change, to be sure. When I looked through Zashi’s private exchanges a year ago, its built-in Tor client was one of the extras I listed. Practical, of course, but on condition that you register at that time. Zodl’s new configuration instead makes network-level protection the starting point.
As such, let’s uncover the basics of this remarkable setup and Also highlight some of the other major industry efforts ramping up to curb metadata leaks.
Mobile wallets are generally lightweight wallets, meaning they do not store a full copy of the blockchain. Instead, they rely on a server to retrieve data and broadcast transactions, and that server can see your IP address, the data you requested and When you asked.
On Zcash, this role falls to lightwalletd servers, and even if your ZEC is fully protected (i.e. encrypted on-chain), these connection patterns can still give keen observers insight into who you are and what you do.
This is not a hypothetical worry, as we have seen from such spectators before. Back in 2023, b10c developer documented an entity nicknamed LinkingLion who kept tabs on which Bitcoin nodes were announced first.
The implication? This special point of view could allowed this person or group to pin new BTC transactions to the IP addresses behind them. And if so, they may have benefited from this information for years, since LinkingLion has shown signs of activity dating back to 2018.
My main point is that this type of metadata tracking can be, and already has been, applied around crypto, including privacy projects (for example, b10c spotted the same LinkingLion IP ranges also connecting to Monero nodes).
What’s needed is a new paradigm for plumbing around transactions, and this is where Zodl wallet servers take a step forward.
Previously, Zodl users who wanted their metadata covered had two choices: enable Tor or take the server operator’s word for it.
Zodl’s recently revealed patch uses Oblivious HTTP (OHTTP), a IETF standard which divides an exchange between two parties so that neither sees the full picture. The procedure here is as follows:
1) Your wallet seals every request with encryption that only ZODL’s gateway server can open.
2) Then the sealed request is sent to a relay operated by Cloudflare or Fastly. The relay removes anything that identifies it and forwards it, so it knows your IP address without ever reading your request.
3) The ZODL gateway is then the only where the request is unsealed, after which it is forwarded to lightwalletd. ZODL sees what you asked for, but the only address it sees is the relay address.
Simply put, Cloudflare or Fastly learns WHO asks, ZODL learns What is asked, but neither learns both.
It’s an interesting and practical system, in my opinion. It is open source code Also has a few other defensive mechanics that stand out, like sizable padding and matchless logs.
This is because outgoing requests are completed up to fixed sizes (around 4 KB per stage, with transaction broadcasts rounded to 16 KB or more), and sensitive responses receive the same treatment, so traffic size doesn’t easily reveal what you’ve retrieved.
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As for the logs, they are constructed in such a way that they cannot be matched. Relay request IDs never make it into ZODL logs in raw form. Instead, they are stored as HMAC (i.e. captured fingerprints) under a secret kept only in memory, which disappears each time the gateway is restarted. This dynamic means that no one will later be able to compare ZODL’s logs to those of the relay.
Please note, this is all new code, and Zodl will gradually roll out these servers over the next few days, so they are not yet operational for all users. The main takeaway for now is that their arrival marks a departure from the current status quo of crypto metadata.
The crucial point here is that OHTTP only protects you as long as the relay operator and ZODL never team up. The relay also always sees When you log in and roughly how much data is moved, but not what’s inside that data.
That said, a reviewer on the Zcash forum argued that the launch framework oversold things, since Cloudflare and Fastly are both U.S. companies subject to legal demands, and warned that this system could lull users into complacency. In response, ZODL contributor y4ss agreed with the central point, calling OHTTP “the best default, not a replacement for Tor or Nym against a state adversary.”
Fair enough, isn’t it. And as y4ss noted earlier in the threadIf legal pressure on infrastructure providers is part of your threat model, you could stack Zodl’s Tor option on top of this new system, so that the relay only witnesses a Tor exit from you.
The real victory here is default statusOf course.
When Ethereum’s Kohaku wallet was introduced in October 2025, David Hoffman looked forward to a future in which privacy is built in and is “not an opt-in UX constraint.” Zodl just shipped a version of this for network metadata, and since OHTTP only adds a single relay hop, it’s lightweight enough to leave to everyone.
Zodl’s move is part of a broader campaign against metadata leaks in crypto, with several teams taking their own paths to address the problem.
The most robust solutions we’ve seen, so to speak, are mixed networks.
In short, a mixnet mixes traffic through multiple relays, fills each packet to the same size, and peppers it with decoy messages, so that an observer cannot easily associate what is coming in and what is going out.
Two Zcash wallets already contain a mixnet of Nyma confidentiality network project, by September team update. Zingo offers it as an on/off switch, while Zkool lets you enable it to reach any Zcash node. Nym says he is also in talks with Team Zodl. Last week at Devcon 8, Nym Also unveiled an SDK aiming to bring its mixnet to more wallets and dapps. The problem is speed, because all that mixing adds latency.
On the Ethereum side of the ecosystem, we saw the Ethereum Foundation Kohaku The privacy wallet effort has listed protection against IP and RPC leaks among its goals since the beginning, and a new Kohaku command-line tool now sends everything except RPC calls. via Tor by default (the Ethereum RPC itself remains on Clearnet assuming you run your own node).
Meanwhile, the EF non-cpr proposal from June gives wallets a standard way to connect to an anonymizing network of their choice. The Tor and Nym versions are already live on mainnetand Privacy Pools Web Application v2 adopted it. Simply enable the app’s “Connect with Tor” setting and its RPC traffic will go through anon-rpc.
Notably, Flashbots have also joined the fray. Flashnetunveiled in February, is a research design for anonymous submission of transactions on Ethereum. The idea is that users drop messages into random locations in a shared batch, then divide them into secret chunks across a group of servers. Add up the pieces and the batch reappears, without any message linked to its sender. The goal is anonymity that avoids both the weaker protections of Tor and the lag of a mixnet, although there is no live deployment or benchmarks yet.
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Along the same lines, Bitcoin developers have worked to protect the moment emissions. In April, Bitcoin Core 31.0 added an opt-in private broadcast option that sends transactions you submit through your node only through Tor or I2P (another anonymity network), so recipients never learn your IP address, and each transaction gets its own connection so two of yours can’t be linked together.
This type of mechanism goes directly to the type of surveillance that the aforementioned LinkingLion entity relied on. However, it is still undergoing combat testing. In June, developers revealed a bug this could expose a BTC sender’s IP address when a failed handshake forces the node to try again without Tor, a hole that was closed in 31.1.
So, does OHTTP offer enhanced privacy?
Against a resourceful state adversary, not alone, but that’s no secret. Again default values reaching the largest number of users and protecting each Zodl user’s IP address from its own wallet provider, without any configuration, raises the level of privacy across the board.
There is, however, an intriguing wrinkle to watch out for here. The EF’s anon-rpc post addresses wallets’ reliance on cloud-based gateways, including Cloudflare, as a weakness, as these gateways can monitor requests and refuse to serve them. Zodl, conversely, uses Cloudflare as half of its privacy split.
In fairness, these designs protect against a few different things: OHTTP limits what a company can do. learnwhile anon-rpc is also concerned about who can cut you offand Zodl still lets you switch to community servers in its advanced settings. Even if crypto’s default privacy settings all start to rely on the same few infra giants, that’s a dependency vector to be aware of.
We’ll have to see if other wallets follow Zodl’s lead here, although it seems clear where the industry is headed. The fight against privacy has extended to the network layer, which is arguably where it is most needed right now.
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