Ethereum Foundation Launches Universal Signer App on Passport Prime

The Ethereum Foundation has launched a beta app called Universal Ethereum Signer on Passport Prime, the $349 hardware device built by Foundation. The app lets the Bitcoin-focused device sign Ethereum transactions for the first time through third-party software, and it must be sideloaded by hand until an official app catalog arrives.

Foundation CEO Zach Herbert announced the launch in an interview on Unchained Premium. He said the Ethereum Foundation is working directly with Nicolas Bacca, a Ledger co-founder and now CEO of ZKnox, who wrote the app on KeyOS, the operating system powering Passport Prime. An Ethereum Foundation grant to ZKnox funded the development.

What does the signer actually do?

The concept is straightforward. Users review and approve Ethereum transactions on separate, air-gapped hardware rather than trusting a phone or laptop with private keys. It is the model hardware wallet makers have long promised: keep the keys off the network entirely.

There is a practical catch. Right now, owners must sideload the signer manually onto Passport Prime, meaning they install the software directly instead of downloading it from an official store. Herbert said a future app catalog will let trusted groups push updates straight to users. That catalog is expected in winter 2026. The setup resembles F-Droid on GrapheneOS, where independent developers ship software without a central gatekeeper.

Why Passport Prime matters here

Passport Prime reached general availability in May 2026, following a $6.4 million funding round for Foundation. The device carries a 3.5-inch touchscreen, 50 GB of encrypted storage, a Bitcoin hardware wallet, FIDO security keys, two-factor authentication and encrypted file storage.

Underneath sits KeyOS, an open-source microkernel written in Rust. It runs to roughly 9,000 lines and isolates apps from one another by design. That isolation is the technical argument for hosting third-party signing software on a device that also stores keys.

The stakes have recent history behind them. In October 2026, Foundation dealt with a phishing campaign that hit more than 23,000 customer emails. The company confirmed devices and private keys were not compromised, and funds on Passport devices stayed safe.

What does this change for hardware wallets?

The Ethereum Foundation funding a Ledger co-founder to build signing software for a competing hardware platform is the notable part. It signals the foundation wants secure signing available across multiple devices, rather than leaving Ethereum users dependent on a handful of vendors.

Ethereum support also expands the attack surface in a mundane way: more transaction types, more contracts, more approval screens to read before tapping sign. Hardware security shifts from key storage to user judgment.

The catalog raises a governance question too. Herbert described a system where trusted groups can send updates directly, so how Foundation decides who counts as trusted will shape both the security and the openness of the platform.

For users, the near-term picture is simple. Passport Prime owners comfortable with sideloading can test the beta signer now. Everyone else can reasonably wait for the app catalog expected in winter 2026, when the friction drops and the platform's trust model gets its first real test.