Benchmarks: Add X25519 benchmark.

Cargo.toml

@@ -226,3 +226,7 @@ codegen-units = 1
 [[bench]]
 name = "aead"
 harness = false
+
+[[bench]]
+name = "x25519"
+harness = false

benches/x25519.rs

@@ -0,0 +1,63 @@
+// Copyright 2015-2023 Brian Smith.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+#![allow(missing_docs)]
+
+use criterion::{black_box, criterion_group, criterion_main, BatchSize, Criterion};
+use ring::{
+    agreement::{self, EphemeralPrivateKey, UnparsedPublicKey, X25519},
+    rand,
+};
+
+fn generate_key(c: &mut Criterion) {
+    c.bench_function("x25519_generate_key", |b| {
+        let rng = rand::SystemRandom::new();
+        b.iter(|| {
+            let private_key = EphemeralPrivateKey::generate(&X25519, &rng).unwrap();
+            let _r = black_box(private_key);
+        })
+    });
+}
+
+fn compute_public_key(c: &mut Criterion) {
+    c.bench_function("x25519_compute_public_key", |b| {
+        let rng = rand::SystemRandom::new();
+        let my_private_key = EphemeralPrivateKey::generate(&X25519, &rng).unwrap();
+        b.iter(|| {
+            let public_key = my_private_key.compute_public_key();
+            let _r = black_box(public_key);
+        })
+    });
+}
+
+fn agree_ephemeral(c: &mut Criterion) {
+    c.bench_function("x25519_agree_ephemeral", |b| {
+        let rng = rand::SystemRandom::new();
+        let peer_public_key: [u8; 32] = rand::generate(&rng).unwrap().expose();
+
+        b.iter_batched(
+            || EphemeralPrivateKey::generate(&X25519, &rng).unwrap(),
+            |my_private_key| {
+                let peer_public_key = UnparsedPublicKey::new(&X25519, &peer_public_key);
+                agreement::agree_ephemeral(my_private_key, &peer_public_key, |key_material| {
+                    black_box(<[u8; 32]>::try_from(key_material).unwrap())
+                })
+                .unwrap();
+            },
+            BatchSize::LargeInput,
+        )
+    });
+}
+
+criterion_group!(x25519, generate_key, compute_public_key, agree_ephemeral);
+criterion_main!(x25519);