From b2713b5e0d24c9c546e77a3fee3ba25f89111293 Mon Sep 17 00:00:00 2001
From: Emman <emman.sun@cargosmart.com>
Date: Wed, 15 Dec 2021 08:47:04 +0800
Subject: [PATCH] crypto/ecdsa: draw a fixed amount of entropy while signing

---
 sm2/sm2.go | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/sm2/sm2.go b/sm2/sm2.go
index bbd13ff..ff31793 100644
--- a/sm2/sm2.go
+++ b/sm2/sm2.go
@@ -569,12 +569,9 @@ func Sign(rand io.Reader, priv *ecdsa.PrivateKey, hash []byte) (r, s *big.Int, e
 	}
 	maybeReadByte(rand)
 
-	// Get min(log2(q) / 2, 256) bits of entropy from rand.
-	entropylen := (priv.Curve.Params().BitSize + 7) / 16
-	if entropylen > 32 {
-		entropylen = 32
-	}
-	entropy := make([]byte, entropylen)
+	// Get 256 bits of entropy from rand.
+	entropy := make([]byte, 32)
+
 	_, err = io.ReadFull(rand, entropy)
 	if err != nil {
 		return