feat(bench): add safety number & epoch rotation benchmarks, CI workflow

Add safety_number benchmark to crypto_benchmarks.rs, epoch rotation
(propose_self_update + commit) benchmark to mls_operations.rs, expand
add_member group sizes to include 100, and add .github/workflows/bench.yml
that runs Criterion benchmarks and uploads HTML reports as artifacts.

.github/workflows/bench.yml

@@ -0,0 +1,54 @@
+name: Benchmarks
+
+on:
+  push:
+    branches: [main, v2]
+  pull_request:
+    branches: [main, v2]
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  bench:
+    name: Run Criterion benchmarks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-action@stable
+
+      - name: Install capnp
+        run: sudo apt-get update && sudo apt-get install -y capnproto
+
+      - name: Cache cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-bench-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-bench-
+
+      - name: Run benchmarks
+        run: cargo bench --package quicproquo-core -- --output-format=bencher 2>&1 | tee bench-output.txt
+
+      - name: Upload HTML reports
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: criterion-reports
+          path: target/criterion/
+          retention-days: 30
+
+      - name: Upload raw output
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: bench-output
+          path: bench-output.txt
+          retention-days: 30

crates/quicproquo-core/benches/crypto_benchmarks.rs

@@ -8,7 +8,7 @@
 
 use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion};
 
-use quicproquo_core::{IdentityKeypair, padding};
+use quicproquo_core::{compute_safety_number, IdentityKeypair, padding};
 
 // ── Identity keypair benchmarks ──────────────────────────────────────────────
 
@@ -127,6 +127,17 @@ fn bench_padding(c: &mut Criterion) {
     group.finish();
 }
 
+// ── Safety number benchmarks ─────────────────────────────────────────────────
+
+fn bench_safety_number(c: &mut Criterion) {
+    let key_a = [0x1au8; 32];
+    let key_b = [0x2bu8; 32];
+
+    c.bench_function("safety_number", |b| {
+        b.iter(|| black_box(compute_safety_number(black_box(&key_a), black_box(&key_b))));
+    });
+}
+
 criterion_group!(
     benches,
     bench_identity_keygen,
@@ -134,5 +145,6 @@ criterion_group!(
     bench_identity_verify,
     bench_sealed_sender,
     bench_padding,
+    bench_safety_number,
 );
 criterion_main!(benches);

crates/quicproquo-core/benches/mls_operations.rs

@@ -62,8 +62,8 @@ fn bench_group_create(c: &mut Criterion) {
 
 fn bench_add_member(c: &mut Criterion) {
     let mut group = c.benchmark_group("mls_add_member");
-    // Smaller sizes to keep setup time reasonable
+    group.sample_size(10);
-    for size in [2, 10, 50] {
+    for size in [2, 10, 50, 100] {
         group.bench_with_input(BenchmarkId::from_parameter(size), &size, |b, &size| {
             b.iter_batched(
                 || {
@@ -83,6 +83,29 @@ fn bench_add_member(c: &mut Criterion) {
     group.finish();
 }
 
+fn bench_epoch_rotation(c: &mut Criterion) {
+    let mut group = c.benchmark_group("mls_epoch_rotation");
+    group.sample_size(10);
+    for size in [2, 10, 50] {
+        group.bench_with_input(BenchmarkId::from_parameter(size), &size, |b, &size| {
+            b.iter_batched(
+                || {
+                    let (mut creator, members) = setup_group(size);
+                    // Propose a self-update to simulate epoch rotation
+                    let proposal = creator.propose_self_update().unwrap();
+                    (creator, members, proposal)
+                },
+                |(mut creator, _members, _proposal)| {
+                    // Commit pending proposals (the self-update) to advance the epoch
+                    creator.commit_pending_proposals().unwrap();
+                },
+                BatchSize::SmallInput,
+            );
+        });
+    }
+    group.finish();
+}
+
 fn bench_send_message(c: &mut Criterion) {
     let mut group = c.benchmark_group("mls_send_message");
     for size in [2, 10, 50] {
@@ -127,6 +150,7 @@ criterion_group!(
     bench_keygen,
     bench_group_create,
     bench_add_member,
+    bench_epoch_rotation,
     bench_send_message,
     bench_receive_message,
 );