From bb9edd7bea600b9377ef9d02cab69c548e4a8f20 Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@codecow.com>
Date: Sat, 29 Aug 2026 14:24:56 -0700
Subject: [PATCH] Return exit code from crypto_sign to allow buffer cleanup.

---
 src/assembly/crypto_sign.ts |  8 ++++----
 src/assembly/index.ts       | 14 +++++++-------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/assembly/crypto_sign.ts b/src/assembly/crypto_sign.ts
index 50f6b12..55e2a8a 100644
--- a/src/assembly/crypto_sign.ts
+++ b/src/assembly/crypto_sign.ts
@@ -39,16 +39,14 @@ const S = new StaticArray<u8>(64)
  * @param {StaticArray<u8>} prv 32-byte private key from input buffer
  * @param {StaticArray<u8>} pub 32-byte public key from input buffer
  */
-export function crypto_sign (RS: StaticArray<u8>, M: StaticArray<u8>, mlen: i32, prv: StaticArray<u8>, pub: StaticArray<u8>): void {
+export function crypto_sign (RS: StaticArray<u8>, M: StaticArray<u8>, mlen: i32, prv: StaticArray<u8>, pub: StaticArray<u8>): i32 {
 	// Derive `A` from private key and throw if it does not match public key
 	crypto_derive(A, prv)
 	let c = 0
 	for (let i = 0; i < KEY_BYTELENGTH; i++) {
 		c |= A[i] ^ pub[i]
 	}
-	if (c != 0) {
-		throw new Error('Invalid public key')
-	}
+	if (c != 0) return -1
 
 	// Hash private key to `h`
 	blake2b.init().update(prv, KEY_BYTELENGTH).digest(h)
@@ -88,4 +86,6 @@ export function crypto_sign (RS: StaticArray<u8>, M: StaticArray<u8>, mlen: i32,
 	R.fill(0)
 	memory.copy(changetype<usize>(RS) + 32, changetype<usize>(S), 32)
 	S.fill(0)
+	
+	return 0
 }
diff --git a/src/assembly/index.ts b/src/assembly/index.ts
index 8905fad..a277617 100644
--- a/src/assembly/index.ts
+++ b/src/assembly/index.ts
@@ -131,16 +131,16 @@ export function sign (mlen: i32): void {
 	INPUT_PUB.fill(0)
 
 	// Sign message from buffer, then clear local input
-	crypto_sign(sig, INPUT_MSG, mlen, prv, pub)
+	const result = crypto_sign(OUTPUT_SIGN, INPUT_MSG, mlen, prv, pub)
 	prv.fill(0)
 	pub.fill(0)
 	INPUT_MSG.fill(0)
-
-	// Copy local result to output buffer
-	memory.copy(changetype<usize>(OUTPUT_SIGN), changetype<usize>(sig), SIGNATURE_BYTELENGTH)
-
-	// Clear local result
-	sig.fill(0)
+	
+	// Clear signature output buffer if signing failed	
+	if (result != 0) {
+		OUTPUT_SIGN.fill(0)
+		throw new Error('Failed to sign, check keypair and message are valid')
+	}
 }
 
 /**
-- 
2.52.0