Project still maintained?

I got to this project following the Google documentation about Binary Authorization:
https://cloud.google.com/binary-authorization/docs/creating-attestations-voucher

They mention two options for security vulnerability attestations, Kritis and Voucher.
I noticed that Kritis might not be maintained anymore (https://github.com/grafeas/kritis/issues/632)

Is Voucher is still maintained?

The README of this project mentions: "Binary authorization uses an admission controller such as [Kritis](https://github.com/grafeas/kritis)", does Voucher use Kritis?, or are these totally separate?

Read the README statement about Binary Authorization and Kritis, then compare it with the linked Google Binary Authorization documentation and the Kritis issue. Done means confirming whether Voucher is maintained and documenting whether it uses Kritis or is separate; the issue does not identify a code or test file to change.

Written by the indexing model from the issue text.