From 045548f7bec7e41d80796da507348983917462f0 Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@codecow.com>
Date: Mon, 24 Aug 2026 15:26:47 -0700
Subject: [PATCH] Hoist buffer pointers to only reach into wasm once per buffer
 instead of every call site. Export buffer sizes for consistency when
 clearing.

---
 src/assembly/index.ts |  6 +++---
 src/lib/nano25519.ts  | 42 ++++++++++++++++++++----------------------
 2 files changed, 23 insertions(+), 25 deletions(-)

diff --git a/src/assembly/index.ts b/src/assembly/index.ts
index 443e0b6..343ad17 100644
--- a/src/assembly/index.ts
+++ b/src/assembly/index.ts
@@ -10,9 +10,9 @@ const PUBLICKEY_BYTES: i32 = 32
 const SIGNATURE_BYTES: i32 = 64
 
 // Static I/O buffers
-const INPUT_BUFFER_BYTES: i32 = SIGNATURE_BYTES + PUBLICKEY_BYTES
-const MESSAGE_BUFFER_BYTES: i32 = 32768
-const OUTPUT_BUFFER_BYTES: i32 = SIGNATURE_BYTES
+export const INPUT_BUFFER_BYTES: i32 = SIGNATURE_BYTES + PUBLICKEY_BYTES
+export const MESSAGE_BUFFER_BYTES: i32 = 32768
+export const OUTPUT_BUFFER_BYTES: i32 = SIGNATURE_BYTES
 const INPUT_BUFFER = new StaticArray<u8>(INPUT_BUFFER_BYTES)
 const MESSAGE_BUFFER = new StaticArray<u8>(MESSAGE_BUFFER_BYTES)
 const OUTPUT_BUFFER = new StaticArray<u8>(OUTPUT_BUFFER_BYTES)
diff --git a/src/lib/nano25519.ts b/src/lib/nano25519.ts
index cdd0642..a5e1b21 100644
--- a/src/lib/nano25519.ts
+++ b/src/lib/nano25519.ts
@@ -12,6 +12,9 @@ type Exports = {
 		getInputPointer: () => number
 		getMessagePointer: () => number
 		getOutputPointer: () => number
+		INPUT_BUFFER_BYTES: WebAssembly.Global
+		MESSAGE_BUFFER_BYTES: WebAssembly.Global
+		OUTPUT_BUFFER_BYTES: WebAssembly.Global
 		memory: WebAssembly.Memory
 	}
 }
@@ -42,6 +45,12 @@ const { exports } = new WebAssembly.Instance(module, {
 		}
 	}
 }) as Exports
+const IN_LEN = exports.INPUT_BUFFER_BYTES.value
+const MSG_LEN = exports.MESSAGE_BUFFER_BYTES.value
+const OUT_LEN = exports.OUTPUT_BUFFER_BYTES.value
+const IN_PTR = exports.getInputPointer()
+const MSG_PTR = exports.getMessagePointer()
+const OUT_PTR = exports.getOutputPointer()
 
 export function derive (k: unknown, out?: unknown): string | Uint8Array<ArrayBuffer> | void {
 	if (typeof out !== 'undefined' && !(isBytes(out) && out.byteLength === 32)) {
@@ -52,15 +61,13 @@ export function derive (k: unknown, out?: unknown): string | Uint8Array<ArrayBuf
 	let buffer = new Uint8Array(exports.memory.buffer)
 	try {
 		privateKey.set(normalize('private key', 32, 32, k))
-		let inPtr = exports.getInputPointer()
 		for (let i = 0; i < 32; i++) {
-			buffer[inPtr + i] = privateKey[i]
+			buffer[IN_PTR + i] = privateKey[i]
 		}
 		exports.derive()
-		const outPtr = exports.getOutputPointer()
 		buffer = new Uint8Array(exports.memory.buffer)
 		for (let i = 0; i < 32; i++) {
-			publicKey[i] = buffer[outPtr + i]
+			publicKey[i] = buffer[OUT_PTR + i]
 		}
 		if (typeof k === 'string') {
 			let hex = ''
@@ -90,20 +97,17 @@ export function sign (m: unknown, k: unknown, s?: unknown): string | Uint8Array<
 	let buffer = new Uint8Array(exports.memory.buffer)
 	try {
 		secretKey.set(normalize('secret key', 64, 64, k))
-		let inPtr = exports.getInputPointer()
 		for (let i = 0; i < 64; i++) {
-			buffer[inPtr + i] = secretKey[i]
+			buffer[IN_PTR + i] = secretKey[i]
 		}
 		const message = normalize('message', 0, mLen, m)
-		let mPtr = exports.getMessagePointer()
 		for (let i = 0; i < message.byteLength; i++) {
-			buffer[mPtr + i] = message[i]
+			buffer[MSG_PTR + i] = message[i]
 		}
 		exports.sign(message.byteLength)
-		const outPtr = exports.getOutputPointer()
 		buffer = new Uint8Array(exports.memory.buffer)
 		for (let i = 0; i < 64; i++) {
-			signature[i] = buffer[outPtr + i]
+			signature[i] = buffer[OUT_PTR + i]
 		}
 		if (typeof k === 'string') {
 			let hex = ''
@@ -130,17 +134,14 @@ export function verify (s: unknown, m: unknown, k: unknown): boolean {
 		const signature = normalize('signature', 64, 64, s)
 		const message = normalize('message', 0, mLen, m)
 		const publicKey = normalize('public key', 32, 32, k)
-		let mPtr = exports.getMessagePointer()
-		let inPtr = exports.getInputPointer()
 		for (let i = 0; i < message.byteLength; i++) {
-			buffer[mPtr + i] = message[i]
+			buffer[MSG_PTR + i] = message[i]
 		}
 		for (let i = 0; i < 64; i++) {
-			buffer[inPtr + i] = signature[i]
+			buffer[IN_PTR + i] = signature[i]
 		}
-		inPtr += 64
 		for (let i = 0; i < 32; i++) {
-			buffer[inPtr + i] = publicKey[i]
+			buffer[IN_PTR + 64 + i] = publicKey[i]
 		}
 		const v = exports.verify(message.byteLength)
 		return v === 0
@@ -150,12 +151,9 @@ export function verify (s: unknown, m: unknown, k: unknown): boolean {
 }
 
 function clear (memory: Uint8Array): void {
-	let inPtr = exports.getInputPointer()
-	let msgPtr = exports.getMessagePointer()
-	let outPtr = exports.getOutputPointer()
-	memory.fill(0, inPtr, inPtr + 96)
-	memory.fill(0, msgPtr, msgPtr + mLen)
-	memory.fill(0, outPtr, outPtr + 64)
+	memory.fill(0, IN_PTR, IN_LEN)
+	memory.fill(0, MSG_PTR, MSG_LEN)
+	memory.fill(0, OUT_PTR, OUT_LEN)
 }
 
 function isBytes (a: unknown): a is Uint8Array<ArrayBuffer> {
-- 
2.52.0