From b71641a15ff1ed08da6c696c25e73b2eba69c802 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Sat, 11 Apr 2026 12:38:03 +0000
Subject: [PATCH] =?UTF-8?q?fix:=20fair=20C-to-C=20benchmark=20=E2=80=94=20?=
 =?UTF-8?q?ACINQ=20sign=20must=20include=20keypair=5Fcreate?=
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The previous benchmark unfairly gave ACINQ a cached keypair (created
once outside the loop) while our sign derived the pubkey each call.

Fixed to test both patterns:
- "sign (full)": both derive pubkey each call
  ACINQ: keypair_create + sign32 = 36.3µs
  Ours: ecmult_gen + sign_internal = 33.6µs → 1.08x faster

- "sign (cached)": both reuse precomputed pubkey
  ACINQ: sign32 with cached keypair = 18.8µs
  Ours: signXOnly with cached xonly = 17.4µs → 1.08x faster

Fair native C-to-C results (x86_64, BMI2):
  pubkeyCreate:          ACINQ 18.0  Ours 16.3  1.10x faster ✓
  sign (full):           ACINQ 36.3  Ours 33.6  1.08x faster ✓
  sign (cached):         ACINQ 18.8  Ours 17.4  1.08x faster ✓
  verify (BIP-340):      ACINQ 36.7  Ours 40.4  0.91x slower ✗
  verifyFast (Nostr):    ACINQ 36.7  Ours 34.5  1.06x faster ✓
  ECDH (cached):         ACINQ 37.2  Ours 35.4  1.05x faster ✓
  batch(200):            ACINQ 42.4  Ours  8.3  5.1x faster  ✓

We beat ACINQ on 5 of 6 operations. The only loss is full BIP-340
verify (0.91x) due to ACINQ's 5x52+ADCX/ADOX field assembly.

https://claude.ai/code/session_011KVZhDcV2G7idNWEBz12GY
---
 quartz/src/main/c/secp256k1/bench_vs_acinq.c | 24 +++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/quartz/src/main/c/secp256k1/bench_vs_acinq.c b/quartz/src/main/c/secp256k1/bench_vs_acinq.c
index 790802a9d..faef2313e 100644
--- a/quartz/src/main/c/secp256k1/bench_vs_acinq.c
+++ b/quartz/src/main/c/secp256k1/bench_vs_acinq.c
@@ -144,12 +144,14 @@ int main(void) {
     double our_pubkey = (now_us() - t0) / N;
     printf("%-30s %10.1f   %10.1f   %8.2fx\n", "pubkeyCreate", acinq_pubkey, our_pubkey, acinq_pubkey/our_pubkey);
 
-    /* --- signSchnorr --- */
+    /* --- signSchnorr (FAIR: both derive pubkey each call) --- */
     N = 5000;
     t0 = now_us();
     for (int i = 0; i < N; i++) {
         uint8_t s[64];
-        secp256k1_schnorrsig_sign32(acinq_ctx, s, msg, &acinq_kp, NULL);
+        secp256k1_keypair kp_fresh;
+        secp256k1_keypair_create(acinq_ctx, &kp_fresh, PRIVKEY);
+        secp256k1_schnorrsig_sign32(acinq_ctx, s, msg, &kp_fresh, NULL);
     }
     double acinq_sign = (now_us() - t0) / N;
 
@@ -159,7 +161,23 @@ int main(void) {
         secp256k1c_schnorr_sign(s, msg, 32, PRIVKEY, NULL);
     }
     double our_sign = (now_us() - t0) / N;
-    printf("%-30s %10.1f   %10.1f   %8.2fx\n", "signSchnorr", acinq_sign, our_sign, acinq_sign/our_sign);
+    printf("%-30s %10.1f   %10.1f   %8.2fx\n", "sign (full, derive pubkey)", acinq_sign, our_sign, acinq_sign/our_sign);
+
+    /* --- signSchnorr (CACHED: both reuse precomputed pubkey) --- */
+    t0 = now_us();
+    for (int i = 0; i < N; i++) {
+        uint8_t s[64];
+        secp256k1_schnorrsig_sign32(acinq_ctx, s, msg, &acinq_kp, NULL);
+    }
+    double acinq_sign_cached = (now_us() - t0) / N;
+
+    t0 = now_us();
+    for (int i = 0; i < N; i++) {
+        uint8_t s[64];
+        secp256k1c_schnorr_sign_xonly(s, msg, 32, PRIVKEY, our_xonly, NULL);
+    }
+    double our_sign_cached = (now_us() - t0) / N;
+    printf("%-30s %10.1f   %10.1f   %8.2fx\n", "sign (cached pubkey)", acinq_sign_cached, our_sign_cached, acinq_sign_cached/our_sign_cached);
 
     /* --- verifySchnorr (ACINQ = always full BIP-340) --- */
     N = 5000;