From c802134737a2599785ec46ebae12b75f0bf96629 Mon Sep 17 00:00:00 2001
From: Martin Costello <martin@martincostello.com>
Date: Sat, 4 Jan 2020 20:39:24 +0000
Subject: [PATCH] Use ISystemClock for request timestamps (#18124)

Use ISystemClock to generate timestamps for Twitter authentication.
Remove custom static field for the epoch.
---
 src/Security/Authentication/Twitter/src/TwitterHandler.cs | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/Security/Authentication/Twitter/src/TwitterHandler.cs b/src/Security/Authentication/Twitter/src/TwitterHandler.cs
index e963d7a27e..5f09e608b9 100644
--- a/src/Security/Authentication/Twitter/src/TwitterHandler.cs
+++ b/src/Security/Authentication/Twitter/src/TwitterHandler.cs
@@ -21,8 +21,6 @@ namespace Microsoft.AspNetCore.Authentication.Twitter
 {
     public class TwitterHandler : RemoteAuthenticationHandler<TwitterOptions>
     {
-        private static readonly DateTime Epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
-
         private HttpClient Backchannel => Options.Backchannel;
 
         /// <summary>
@@ -301,9 +299,9 @@ namespace Microsoft.AspNetCore.Authentication.Twitter
             return result;
         }
 
-        private static string GenerateTimeStamp()
+        private string GenerateTimeStamp()
         {
-            var secondsSinceUnixEpocStart = DateTime.UtcNow - Epoch;
+            var secondsSinceUnixEpocStart = Clock.UtcNow - DateTimeOffset.UnixEpoch;
             return Convert.ToInt64(secondsSinceUnixEpocStart.TotalSeconds).ToString(CultureInfo.InvariantCulture);
         }