Add chacha20_poly1305 Criterion AEAD benchmarks

Existing benches only use the raw ChaCha20 keystream without
Poly1305/authentication overhead.

Add Criterion benchmarks to ChaCha20-Poly1305 using AEAD encrypt/decrypt
with and without AAD.

Author: jamillambert

benches/Cargo.toml

@@ -29,6 +29,11 @@ path = "bitcoin/witness.rs"
 harness = false
 
 
+[[bench]]
+name = "chacha20poly1305"
+path = "chacha20_poly1305/chacha20poly1305.rs"
+harness = false
+
 [[bench]]
 name = "chacha20"
 path = "chacha20_poly1305/chacha20.rs"

benches/chacha20_poly1305/chacha20poly1305.rs

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: CC0-1.0
+
+use std::hint::black_box;
+
+use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion, Throughput};
+use std::time::Duration;
+
+use chacha20_poly1305::{ChaCha20Poly1305, Key, Nonce};
+
+fn bench_chacha20poly1305(c: &mut Criterion) {
+    let mut g = c.benchmark_group("chacha20poly1305");
+    g.measurement_time(Duration::from_secs(5)).warm_up_time(Duration::from_secs(2));
+
+    for &size in &[128usize, 1024, 16 * 1024, 64 * 1024] {
+        let key = Key::new([0u8; 32]);
+        let nonce = Nonce::new([0u8; 12]);
+
+        let pt = vec![0u8; size];
+        let aad: &[u8] = b"dummy_aad";
+
+        g.throughput(Throughput::Bytes(size as u64));
+
+        g.bench_function(BenchmarkId::new("encrypt_no_aad", size), |b| {
+            b.iter(|| {
+                let mut buf = pt.clone();
+                let cipher = ChaCha20Poly1305::new(key, nonce);
+                let tag = cipher.encrypt(black_box(&mut buf), None);
+                black_box(tag);
+            });
+        });
+
+        g.bench_function(BenchmarkId::new("encrypt_with_aad", size), |b| {
+            b.iter(|| {
+                let mut buf = pt.clone();
+                let cipher = ChaCha20Poly1305::new(key, nonce);
+                let tag = cipher.encrypt(black_box(&mut buf), Some(aad));
+                black_box(tag);
+            });
+        });
+
+        let mut ct = pt.clone();
+        let tag = ChaCha20Poly1305::new(key, nonce).encrypt(&mut ct, Some(aad));
+
+        g.bench_function(BenchmarkId::new("decrypt_ok", size), |b| {
+            b.iter(|| {
+                let mut buf = ct.clone();
+                let cipher = ChaCha20Poly1305::new(key, nonce);
+                let res = cipher.decrypt(black_box(&mut buf), tag, Some(aad));
+                black_box(res.unwrap());
+            });
+        });
+    }
+
+    g.finish();
+}
+
+criterion_group!(benches, bench_chacha20poly1305);
+criterion_main!(benches);