Hi! It's been a while since you've heard from us at Tillitis. We have been working on improvements to TKey that we are now ready to release as an alpha release. Code name for the next generation of TKey is Castor. With this release we are ready to receive feedback, being on the new features as such or if you actually try Castor on target and find improvements.

Castor runs on existing TKey hardware, so if you have a TKey Unlocked you can test Castor on target.

The major changes in Castor are: - Persistent storage on flash with space for two pre-loaded device apps and space for up to four device app storage areas, isolated from each other by firmware. - Support for automatically starting a pre-loaded app. - Support for chaining of apps, including chaining trust by demanding that the next app in the chain should have a specific digest. - System calls to access the file system with hardware support for the privilege raising/lowering. - More USB endpoints besides CDC, including as a security token HID and CCID. - Reset function, to restart TKey without the need to power cycle by removing and inserting TKey in USB port. - Faster USB access.

We believe all functionality we sketched out for Castor is already there, but it's not yet completely reviewed and audited. The build process, including getting the filesystem to flash, is also not streamlined. There are things to polish, but the platform is usable.

See the release notes[1] for the complete list of new features for the upcoming Castor release. Information on how to go about to test Castor is also found in the release notes.

TKey Device Signer (main branch[2]) is updated to work with Castor, for you who like to test.

Preliminary app developer documentation for Castor alpha release can be found in the developer handbook[3].

NOTE WELL: BREAKING CHANGE! Older device apps WILL NOT WORK. The way device apps communicate has changed. In order to support several USB endpoints we have introduced a small internal protocol to address which endpoint the device app is communicating with.

[1]: https://github.com/tillitis/tillitis-key1/blob/main/doc/release_notes.md [2]: https://github.com/tillitis/tkey-device-signer [3]: https://dev.tillitis.se/castor/