Allow library users to bring their own crypto providers

Cargo.toml

@@ -55,15 +55,15 @@ tracing-subscriber =  { version = "0.3.16", features = ["env-filter"] }
 
 [[example]]
 name = "provision"
-required-features = ["hyper-rustls", "rcgen"]
+required-features = ["hyper-rustls", "rcgen", "aws-lc-rs"]
 
 # Pebble integration test.
 # Ignored by default because it requires pebble & pebble-challtestsrv.
 # Run with:
 #  PEBBLE=path/to/pebble CHALLTESTSRV=path/to/pebble-challtestsrv cargo test -- --ignored
 [[test]]
 name = "pebble"
-required-features = ["hyper-rustls"]
+required-features = ["hyper-rustls", "rcgen"]
 
 [package.metadata.docs.rs]
 # all non-default features except fips (cannot build on docs.rs environment)
@@ -76,6 +76,7 @@ allowed_external_types = [
     "http::*",
     "http_body::*",
     "hyper::*",
+    "rustls::crypto::CryptoProvider",
     "rustls_pki_types::*",
     "serde_core::*",
     "serde_json::*",

examples/provision.rs

@@ -1,11 +1,13 @@
+#![cfg(any(feature = "ring", feature = "aws-lc-rs"))]
 use std::io;
 
 use clap::Parser;
+use rustls::crypto::CryptoProvider as RustlsCryptoProvider;
 use tracing::info;
 
 use instant_acme::{
-    Account, AuthorizationStatus, ChallengeType, Identifier, LetsEncrypt, NewAccount, NewOrder,
-    OrderStatus, RetryPolicy,
+    Account, AuthorizationStatus, ChallengeType, CryptoProvider, Identifier, LetsEncrypt,
+    NewAccount, NewOrder, OrderStatus, RetryPolicy,
 };
 
 #[tokio::main]
@@ -17,7 +19,13 @@ async fn main() -> anyhow::Result<()> {
     // Alternatively, restore an account from serialized credentials by
     // using `Account::from_credentials()`.
 
-    let (account, credentials) = Account::builder()?
+    #[cfg(feature = "aws-lc-rs")]
+    let provider = CryptoProvider::aws_lc_rs();
+
+    #[cfg(all(feature = "ring", not(feature = "aws-lc-rs")))]
+    let provider = CryptoProvider::ring();
+
+    let (account, credentials) = Account::builder(provider, rustls_crypto_provider())?
         .create(
             &NewAccount {
                 contact: &[],
@@ -71,7 +79,7 @@ async fn main() -> anyhow::Result<()> {
         println!(
             "_acme-challenge.{} IN TXT {}",
             challenge.identifier(),
-            challenge.key_authorization().dns_value()
+            challenge.key_authorization()?.dns_value()
         );
         io::stdin().read_line(&mut String::new())?;
 
@@ -100,3 +108,13 @@ struct Options {
     #[clap(long)]
     names: Vec<String>,
 }
+
+#[cfg(feature = "aws-lc-rs")]
+fn rustls_crypto_provider() -> RustlsCryptoProvider {
+    rustls::crypto::aws_lc_rs::default_provider()
+}
+
+#[cfg(all(feature = "ring", not(feature = "aws-lc-rs")))]
+fn rustls_crypto_provider() -> RustlsCryptoProvider {
+    rustls::crypto::ring::default_provider()
+}