From 2c751b9bc9d7677897b667116b45c36638b2c6c3 Mon Sep 17 00:00:00 2001
From: "Tommaso Gagliardoni (Kudelski Security)"
 <80652589+tgkudelski@users.noreply.github.com>
Date: Wed, 10 Jan 2024 16:46:25 +0100
Subject: [PATCH] Update poly.go

---
 crystals-kyber/poly.go | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/crystals-kyber/poly.go b/crystals-kyber/poly.go
index f2922da..1d19a70 100644
--- a/crystals-kyber/poly.go
+++ b/crystals-kyber/poly.go
@@ -165,19 +165,20 @@ func polyFromMsg(msg []byte) Poly {
 //polyToMsg converts a polynomial to a byte array - fixed against https://kyberslash.cr.yp.to/faq.html
 func polyToMsg(p Poly) []byte {
 	msg := make([]byte, 32)
-	var t uint16
-	//var t uint32
+	//var t uint16
+	var t uint32
 	var tmp byte
 	p.reduce()
 	for i := 0; i < n/8; i++ {
 		tmp = 0
 		for j := 0; j < 8; j++ {
-			t = (((uint16(p[8*i+j]) << 1) + uint16(q/2)) / uint16(q)) & 1
-			//t <<= 1
-			//t += 1665
-			//t *= 80635
-			//t >>= 28
-			//t &= 1
+			//t = (((uint16(p[8*i+j]) << 1) + uint16(q/2)) / uint16(q)) & 1
+			t = uint32(p[8*i+j])
+			t <<= 1
+			t += 1665
+			t *= 80635
+			t >>= 28
+			t &= 1
 			tmp |= byte(t << j)
 		}
 		msg[i] = tmp