From a90387d2f39f4d97976cdc05c6166d715e2963c9 Mon Sep 17 00:00:00 2001
From: Millicent Achieng <achieng.milli@gmail.com>
Date: Wed, 29 Mar 2023 14:39:42 +0300
Subject: [PATCH] Make hasher static and readonly in the
 CryptographicExtensions

---
 .../Common/CryptographyExtensions.cs                      | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/Microsoft.OpenApi.OData.Reader/Common/CryptographyExtensions.cs b/src/Microsoft.OpenApi.OData.Reader/Common/CryptographyExtensions.cs
index 46e3dff1..de93a5cb 100644
--- a/src/Microsoft.OpenApi.OData.Reader/Common/CryptographyExtensions.cs
+++ b/src/Microsoft.OpenApi.OData.Reader/Common/CryptographyExtensions.cs
@@ -5,11 +5,14 @@
 
 using System.Security.Cryptography;
 using System.Text;
+using System.Threading;
 
 namespace Microsoft.OpenApi.OData.Common
 {
     internal static class CryptographyExtensions
     {
+         private static readonly ThreadLocal<SHA256> hasher = new (SHA256.Create);
+
         /// <summary>
         /// Calculates the SHA256 hash for the given string.
         /// </summary>
@@ -17,10 +20,9 @@ internal static class CryptographyExtensions
         public static string GetHashSHA256(this string input)
         {
             Utils.CheckArgumentNull(input, nameof(input));
-
-            var hasher = new SHA256CryptoServiceProvider();
+  
             var inputBytes = Encoding.UTF8.GetBytes(input);
-            var hashBytes = hasher.ComputeHash(inputBytes);
+            var hashBytes = hasher.Value.ComputeHash(inputBytes);
             var hash = new StringBuilder();
             foreach (var b in hashBytes)
             {