Breez SDK Ditches Seed Phrases for Passkey Login
On March 18, 2026, Bitcoin software lab Breez introduced Passkey Login to its SDK, enabling developers to build self-custodial wallets that no longer require a mandatory seed phrase. The move is designed to eliminate a significant onboarding obstacle that Breez identifies as a primary reason mainstream users avoid holding their own Bitcoin, opting instead for the counterparty risk of exchanges and custodial apps.
The seed phrase has been a barrier to self-custody since day one. It’s what scares normies away from keeping their own bitcoin... Passkey Login doesn’t eliminate the tradeoffs of self-custody, but it reframes them around something people already understand and use, namely the same biometric authentication that protects their banking app and their password manager.
PRF Extension Solves Key Hurdle for FIDO2 Wallets
Standard passkeys, a security credential promoted by major tech firms like Apple and Google since 2022, have seen rapid adoption with over a billion activations reported by the FIDO Alliance as of mid-2025. While effective for authentication, they were initially unsuitable for Bitcoin wallets, which rely on a single seed (like a BIP-39 phrase) to deterministically generate all necessary keys and addresses.
Breez's solution leverages the Pseudo-Random Function (PRF) extension, a newer capability within the WebAuthn Level 3 specification. This function allows a user's passkey—stored in a secure hardware element like Apple's Secure Enclave or Android's Titan chip—to produce a unique, deterministic cryptographic output for any given input. This effectively replicates the function of a seed phrase without ever exposing it or requiring the user to manually back it up.
Balancing User Experience with Recovery Options
This new system ties wallet recovery directly to the user's device and cloud ecosystem. If a device is lost, access is restored through established platforms like iCloud Keychain or Google Password Manager, a familiar process for most smartphone users. This simplifies the user experience by removing the need to safeguard a physical piece of paper.
To ensure interoperability and address potential cross-platform limitations, Breez maintains a backward-compatible recovery path. Users can optionally export a standard 12-word BIP-39 mnemonic phrase for their wallet. This allows them to recover their funds in any other standard Bitcoin wallet, ensuring they retain full control even if they switch to a platform that does not yet support passkey-based logins. A public technical specification and a reference app called "Glow" are available to demonstrate the feature.
