When you want a cryptography library for #guile, you might be pushed to use guile-#gcrypt. I advise you to use #gnutls instead: since guile use gnutls for its web stack, it might save you a dependency, while adding lots of cool features (e.g. parsing PEM keys, a requirement for ActivityPub interoperability with Mastodon).

For instance, here is how #goblins could use it:

https://gitlab.com/spritely/guile-goblins/-/merge_requests/181