sumdb/note: signed note formats for checksum database

Copied from golang.org/x/exp/sumdb/internal/note.

For golang/go#31761.

Change-Id: Ie1feebc86b6d34a6cdd20ee0c0ba24588841d1c3
Reviewed-on: https://go-review.googlesource.com/c/mod/+/176463
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
5 files changed
tree: 8fee51208f87c609ffcd031123f9ff6fbb8bd7a6
  1. LICENSE
  2. PATENTS
  3. README
  4. codereview.cfg
  5. go.mod
  6. go.sum
  7. module/
  8. semver/
  9. sumdb/