Keyholm

Keyholm is all about single-device passkeys (i.e. client-side discoverable credentials) whose private key is protected by secure hardware.

You can never export or sync these passkeys. Think of Keyholm as a way to activate the built-in security key on your phone.



• target devices: phones with secure hardware (including Pixels)

• no INTERNET permission

• no Google Play Services ever

• takes advantage of latest Android version/APIs

• allows extensive control over particulars of what credentials it creates and how


• supports ES256: it's the only EC, StrongBox-backed algorithm

• supports Ed25519: it's not NIST, it's fast and safe but TEE-only

• supports ML-DSA: post-quantum! but Android 17 and TEE-only



• supports android-key attestation

• supports PRF extension

• uses QUERY_ALL_PACKAGES in order to display icons for apps that were denied passkey usage

• account list export/import for making it marginally easier to switch devices. All keys still need to be manually recreated on the new device!