From 14b03e381f02653a2bd2e3df4c9c9dbd76a91d50 Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Fri, 2 Oct 2026 02:27:59 -0700
Subject: [PATCH] Adjust how scratch args are sorted.

---
 src/assembly/ed25519/fe.ts | 25 +++++++++++++++----------
 src/assembly/ed25519/ge.ts | 18 +++++++++---------
 src/assembly/ed25519/p.ts  |  8 ++++----
 3 files changed, 28 insertions(+), 23 deletions(-)

diff --git a/src/assembly/ed25519/fe.ts b/src/assembly/ed25519/fe.ts
index 75c2245..714e9d2 100644
--- a/src/assembly/ed25519/fe.ts
+++ b/src/assembly/ed25519/fe.ts
@@ -14,7 +14,7 @@
  *
  * `n = 2⁰a[0] + 2²⁶a[1] + 2⁷⁷a[2] ... + 2²³⁰a[9]`
  */
-import { load_3, load_4, sodium_is_zero } from './utils'
+import { load_3, load_4 } from './utils'
 
 /**
  * 10x 25- and 26-bit array of values representing a large integer `n mod p`. In
@@ -239,9 +239,9 @@ export function fe_invert (out: FieldElement, z: FieldElement): void {
  * Preconditions:
  * |f| bounded by 1.1x2²⁶,1.1x2²⁵,1.1x2²⁶,1.1x2²⁵,etc.
  */
-export function fe_isnegative (f: FieldElement, t: FieldElement): u8 {
-	fe_reduce(t, f)
-	return u8(t[0] & 1)
+export function fe_isnegative (f: FieldElement, fe_scratch: FieldElement): u8 {
+	fe_reduce(fe_scratch, f)
+	return u8(fe_scratch[0] & 1)
 }
 
 /**
@@ -251,9 +251,14 @@ export function fe_isnegative (f: FieldElement, t: FieldElement): u8 {
  * Preconditions:
  * |f| bounded by 1.1x2²⁶,1.1x2²⁵,1.1x2²⁶,1.1x2²⁵,etc.
  */
-export function fe_iszero (s: StaticArray<u8>, f: FieldElement, t: FieldElement): u8 {
-	fe_tobytes(s, f, t)
-	return sodium_is_zero(s, 32)
+export function fe_iszero (f: FieldElement, u8x32_scratch: StaticArray<u8>, fe_scratch: FieldElement): u8 {
+	fe_tobytes(u8x32_scratch, f, fe_scratch)
+	let d: i32 = 0
+	for (let i: i32 = 0; i < 32; i++) {
+		d |= u8x32_scratch[i]
+	}
+	d &= 255
+	return u8(((d - 1) >> 8) & 1)
 }
 
 /**
@@ -1068,9 +1073,9 @@ export function fe_sub (h: FieldElement, f: FieldElement, g: FieldElement): void
  *
  * Goal: Output h0+...+2²³⁰ h9.
  */
-export function fe_tobytes (s: StaticArray<u8>, h: FieldElement, t: FieldElement): void {
-	fe_reduce(t, h)
-	const t_ptr: usize = changetype<usize>(t)
+export function fe_tobytes (s: StaticArray<u8>, h: FieldElement, fe_scratch: FieldElement): void {
+	fe_reduce(fe_scratch, h)
+	const t_ptr: usize = changetype<usize>(fe_scratch)
 	const t0 = load<i32>(t_ptr, 0)
 	const t1 = load<i32>(t_ptr, 4)
 	const t2 = load<i32>(t_ptr, 8)
diff --git a/src/assembly/ed25519/ge.ts b/src/assembly/ed25519/ge.ts
index 66b8fc1..e979d05 100644
--- a/src/assembly/ed25519/ge.ts
+++ b/src/assembly/ed25519/ge.ts
@@ -135,10 +135,10 @@ export function ge_frombytes_negate_vartime (h: ge_p3, s: StaticArray<u8>): i32
 
 	// m = vx²-u
 	fe_sub(m_root_check, vxx, u)
-	if (fe_iszero(u8x32_scratch, m_root_check, fe_scratch) == 0) {
+	if (fe_iszero(m_root_check, u8x32_scratch, fe_scratch) == 0) {
 		// p = vx²+u
 		fe_add(p_root_check, vxx, u)
-		if (fe_iszero(u8x32_scratch, p_root_check, fe_scratch) == 0) {
+		if (fe_iszero(p_root_check, u8x32_scratch, fe_scratch) == 0) {
 			return -1
 		}
 		fe_mul(h.X, h.X, fe_sqrtm1)
@@ -199,11 +199,11 @@ export function ge_frombytes (h: ge_p3, s: StaticArray<u8>): i32 {
 
 	// m = vx²-u
 	fe_sub(m_root_check, vxx, u)
-	has_m_root = fe_iszero(u8x32_scratch, m_root_check, fe_scratch)
+	has_m_root = fe_iszero(m_root_check, u8x32_scratch, fe_scratch)
 
 	// p = vx²+u
 	fe_add(p_root_check, vxx, u)
-	has_p_root = fe_iszero(u8x32_scratch, p_root_check, fe_scratch)
+	has_p_root = fe_iszero(p_root_check, u8x32_scratch, fe_scratch)
 
 	// x√-1
 	fe_mul(x_sqrtm1, h.X, fe_sqrtm1)
@@ -226,14 +226,14 @@ export function ge_has_small_order (p: ge_p3): i32 {
 	const fe_scratch = ge_has_small_order_fe_scratch
 	let ret: i32 = 0
 
-	ret |= fe_iszero(u8x32_scratch, p.X, fe_scratch)
-	ret |= fe_iszero(u8x32_scratch, p.Y, fe_scratch)
-	ret |= fe_iszero(u8x32_scratch, p.Z, fe_scratch)
+	ret |= fe_iszero(p.X, u8x32_scratch, fe_scratch)
+	ret |= fe_iszero(p.Y, u8x32_scratch, fe_scratch)
+	ret |= fe_iszero(p.Z, u8x32_scratch, fe_scratch)
 	fe_mul(y_sqrtm1, p.Y, fe_sqrtm1)
 	fe_sub(c, y_sqrtm1, p.X)
-	ret |= fe_iszero(u8x32_scratch, c, fe_scratch)
+	ret |= fe_iszero(c, u8x32_scratch, fe_scratch)
 	fe_add(c, y_sqrtm1, p.X)
-	ret |= fe_iszero(u8x32_scratch, c, fe_scratch)
+	ret |= fe_iszero(c, u8x32_scratch, fe_scratch)
 
 	return ret
 }
diff --git a/src/assembly/ed25519/p.ts b/src/assembly/ed25519/p.ts
index 401cd0f..6874727 100644
--- a/src/assembly/ed25519/p.ts
+++ b/src/assembly/ed25519/p.ts
@@ -105,20 +105,20 @@ export function ge_p3_to_cached (r: ge_cached, p: ge_p3): void {
 	fe_mul(r.T2d, p.T, ed25519_d2)
 }
 
-const ge_p3_tobytes_t: FieldElement = fe()
+const ge_p3_tobytes_fe_scratch: FieldElement = fe()
 const ge_p3_tobytes_recip: FieldElement = fe()
 const ge_p3_tobytes_x: FieldElement = fe()
 const ge_p3_tobytes_y: FieldElement = fe()
 export function ge_p3_tobytes (s: StaticArray<u8>, h: ge_p3): void {
-	const t = ge_p3_tobytes_t
+	const fe_scratch = ge_p3_tobytes_fe_scratch
 	const recip = ge_p3_tobytes_recip
 	const x = ge_p3_tobytes_x
 	const y = ge_p3_tobytes_y
 	fe_invert(recip, h.Z)
 	fe_mul(x, h.X, recip)
 	fe_mul(y, h.Y, recip)
-	fe_tobytes(s, y, t)
-	s[31] ^= fe_isnegative(x, t) << 7
+	fe_tobytes(s, y, fe_scratch)
+	s[31] ^= fe_isnegative(x, fe_scratch) << 7
 }
 
 const ge_p2_dbl_t: FieldElement = fe()
-- 
2.52.0