There is OpenBSDs signify which is used for their packaging: https://www.openbsd.org/papers/bsdcan-signify.html
https://man.openbsd.org/signify.1
There's also a NIH version of this that I and a friend put together: https://github.com/ruuda/tako
https://man.openbsd.org/signify.1
There's also a NIH version of this that I and a friend put together: https://github.com/ruuda/tako