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!

Keyholm's first release on fdroid! It's quite feature complete already when it comes to single-device passkeys:

- Passkey creation/passkey use as an Android passkey service
- Passkey management
- Extensive settings for configuring exactly how to create/use your passkeys
- PRF support
- Passkey list export/import
- Icon pack support
- Editable RP name, username and display name
- Non-discoverable passkeys

This will hopefully be the same as v0.1, which will be the first release to guarantee back