Cargo Features

[dependencies]
http_digest_headers = { version = "0.1.0", default-features = false, features = ["use_openssl", "use_ring"] }
default = use_openssl

The use_openssl feature is set by default whenever http_digest_headers is added without default-features = false somewhere in the dependency tree.

use_openssl default = openssl
use_ring = ring

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

openssl use_openssl
ring use_ring?

Enables ring ^0.16.20