At a high level CMS defines a way to digitally sign and authenticate arbitrary content.
cms-rs is a fork of cryptographic-message-syntax, a pure Rust implementation
of Cryptographic Message Syntax (CMS) as defined by RFC 5652, which was first
developed as part of the
PyOxidizer project.
Because the original cryptographic-message-syntax crate has been removed from
later versions of the PyOxidizer project, and it's not obvious how the source
code is being maintained, I "forked" the 0.18.0 version of it by importing the
source directly from
https://crates.io/api/v1/crates/cryptographic-message-syntax/0.18.0/download,
and adding subsequent modifications on top of this base version, in this
repository.