Breez, a company specialized in solutions for Bitcoin’s Lightning Network (LN), launched version 0.9.1 of its software development kit (SDK) with support for passkeys on March 18. The update allows developers to build self-custodial Bitcoin wallets that can be created and used exclusively with fingerprint or facial recognition: the user never needs to generate or write down a seed phrase to start using them. In everyday use, with the new Breez implementation, the user you won’t need to manage a 12 or 24 word seed phrase. These words are the main access and recovery mechanism in this type of wallets, and are generated following the BIP-39 and BIP-32 standards. With this passkey model, the process occurs automatically with each authentication: the keys are never stored on the device or on external servers. Losing that seed phrase is equivalent to losing permanent access to funds. That risk has historically been one of the main obstacles to the mass adoption of self-custodial wallets. A passkey is a digital authentication method that allows you to log into accounts and applications without using passwords. It works using public key cryptography, linking the account directly to a device (such as a cell phone or computer) and validating the user’s identity through biometric data—fingerprint or facial recognition—or the screen lock PIN. As passkeys are immune to phishing, they offer a higher layer of security than traditional keys. Breez noted that he is aiming to remove the hurdle of managing recovery seeds in daily use. The team summed up the launch with one sentence: “The future of user experience in Bitcoin is here.”
How does the mechanism work?
According to the Breez repository, when the user authenticates with biometrics, the passkey activates a cryptographic function called PRF (Pseudorandom Function). This function always generates the same root key when combined with the same passkey and the same wallet. That allows rebuild Bitcoin keys at any time without having to have previously saved them. The passkey itself is a credential stored in the device’s secure enclave, a hardware component isolated from the rest of the system specifically designed to protect sensitive information (there is a recent history of vulnerabilities to information storage systems in mid-range mobile phones). From this root key, the Bitcoin keys are derived following the BIP-39 and BIP-32 standards. The process repeats from scratch on each authentication and the keys are not stored on the device or on external servers. The Breez kit also allows manage multiple wallets under the same passkeyeach identified with a different label, for example, «work» or «savings.» These tags are registered in Nostr, a decentralized messaging network, allowing them to be retrieved from any device without depending on a central server. The seed phrase still exists mathematically and can be exported as an optional backup, but the user never needs to see or annotate it to operate. However, the passkey does not sign Bitcoin transactions directly. Its role is to activate the PRF function, which generates the Bitcoin keys. It is these keys that ultimately authorize each transaction, exactly the same as in any traditional wallet. Biometrics is the key that opens the process, not the signature that seals the operation.
What does the user gain and what does he assume?
Breez’s proposal can be summed up in his own slogan: «No seed, no sweat». The initial configuration process is simplified to the level of opening any application. The user never sees or handles the 12 words in everyday use. Self-custody remains complete because keys are derived directly into the device’s secure enclave and never leave it or reach any server. For new users, that eliminates one of the most common mistakes in the cryptoasset ecosystem: losing or incorrectly managing the seed phrase. Passkeys can sync in the cloud through services such as iCloud Keychain or Google Password Manager, which allows them to be recovered on a new device if the user maintains access to that account. However, if you lose both the device and access to that account and you did not export the seed phrase as a backup, you would permanently lose access to your funds. Additionally, if that cloud account is compromised, the derived keys could be compromised. Lastly, support for the PRF extension is not universal. As noted in the repository, it operates properly on iOS 18 and higher versions, and on Android with Google Password Manager. On Windows, support is more limited.
Breez and its simplification history in Lightning and Bitcoin
This release joins a line of Breez development. In April 2025, as reported by BitcoinDynamic, the company added support for WebAssembly (WASM) to its SDK. WASM is a technology that allows code to run at high speed in web browsers. That update brought Lightning payments to web environments without requiring the user or developer to run full Bitcoin nodes. The new support for passkeys extends that same logic to the problem of access: with a fingerprint, a developer can now offer a self-custodial Bitcoin wallet that is created, used, and recovered without the user ever seeing a seed phrase. Breez’s stated goal is to make trading Bitcoin and Lightning as simple as using any conventional financial app.
