From d4a7e0e2ec8a5f5b910c760fe3c97efd6bc73e8b Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Fri, 5 Dec 2025 09:08:22 -0800
Subject: [PATCH] Public key derivation always multiplies secret key scalar by
 base point G, so eliminate extra multiplication call and code that is never
 called in this particular implementation.

---
 src/lib/crypto/secp256k1.ts | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/src/lib/crypto/secp256k1.ts b/src/lib/crypto/secp256k1.ts
index 0d56660..7d9198c 100644
--- a/src/lib/crypto/secp256k1.ts
+++ b/src/lib/crypto/secp256k1.ts
@@ -19,7 +19,6 @@ type Point = {
 	negate: () => Point
 	double: () => Point
 	add: (other: Point) => Point
-	multiply: (n: bigint) => Point
 	toAffine: () => AffinePoint
 	assertValidity: () => Point
 	toBytes: (isCompressed?: boolean) => Bytes
@@ -217,27 +216,6 @@ export class Secp256k1 {
 				Z3 = M(Z3 + t0) // step 40
 				return secp256k1.Point(X3, Y3, Z3)
 			},
-			/**
-			 * Point-by-scalar multiplication. Scalar must be in range 1 <= n < CURVE.n.
-			 * Uses {@link wNAF} for base point.
-			 * Uses fake point to mitigate side-channel leakage.
-			 * @param n scalar by which point is multiplied
-			 * @param safe safe mode guards against timing attacks; unsafe mode is faster
-			 */
-			multiply (n: bigint): Point {
-				if (secp256k1.bigintInRange(n, 1n, secp256k1.N) === 1n) return this
-				if (this.equals(secp256k1.G)) return secp256k1.wNAF(n).p
-				// init result point & fake point
-				let p = secp256k1.I
-				let f = secp256k1.G
-				for (let d: Point = this; n > 0n; d = d.double(), n >>= 1n) {
-					// if bit is present, add to point
-					// if not present, add to fake, for timing safety
-					if (n & 1n) p = p.add(d)
-					else f = f.add(d)
-				}
-				return p
-			},
 			/** Convert point to 2d xy affine point. (X, Y, Z) ∋ (x=X/Z, y=Y/Z) */
 			toAffine (): AffinePoint {
 				const { X: x, Y: y, Z: z } = this
@@ -325,7 +303,7 @@ export class Secp256k1 {
 
 	/** Creates 33/65-byte public key from 32-byte private key. */
 	static getPublicKey (sk: Bytes, isCompressed = true): Bytes {
-		return this.G.multiply(this.secretKeyToScalar(sk)).toBytes(isCompressed)
+		return this.wNAF(this.secretKeyToScalar(sk)).p.toBytes(isCompressed)
 	}
 
 	static isValidPublicKey (pk: Bytes, isCompressed?: boolean): boolean {
@@ -375,6 +353,7 @@ export class Secp256k1 {
 		return cnd ? n : p
 	}
 	static wNAF (n: bigint): { p: Point; f: Point } {
+		console.log('mult', n)
 		const comp = this.Gpows || (this.Gpows = this.precompute())
 		let p = this.I
 		let f = this.G // f must be G, or could become I in the end
-- 
2.47.3