Adding an environ var (SERedis_ClientCertStorageFlags) for configuring which cert store to check.

StackExchange.Redis/StackExchange/Redis/PhysicalConnection.cs

@@ -616,21 +616,29 @@ internal int GetAvailableInboundBytes(out int activeReaders)
         {
             activeReaders = Interlocked.CompareExchange(ref haveReader, 0, 0);
             return this.socketToken.Available;
-        }
-
-        static LocalCertificateSelectionCallback GetAmbientCertificateCallback()
-        {
-            try
-            {
-                var pfxPath = Environment.GetEnvironmentVariable("SERedis_ClientCertPfxPath");
-                var pfxPassword = Environment.GetEnvironmentVariable("SERedis_ClientCertPassword");
-                if (!string.IsNullOrEmpty(pfxPath) && File.Exists(pfxPath))
-                {
-                    return delegate { return new X509Certificate2(pfxPath, pfxPassword ?? ""); };
-                }                
-            } catch
-            { }
-            return null;
+        }
+
+        static LocalCertificateSelectionCallback GetAmbientCertificateCallback()
+        {
+            try
+            {
+                var pfxPath = Environment.GetEnvironmentVariable("SERedis_ClientCertPfxPath");
+                var pfxPassword = Environment.GetEnvironmentVariable("SERedis_ClientCertPassword");
+                var pfxStorageFlags = Environment.GetEnvironmentVariable("SERedis_ClientCertStorageFlags");
+
+                X509KeyStorageFlags? flags = null;
+                if (!string.IsNullOrEmpty(pfxStorageFlags))
+                {
+                    flags = Enum.Parse(typeof(X509KeyStorageFlags), pfxStorageFlags) as X509KeyStorageFlags?;
+                }
+
+                if (!string.IsNullOrEmpty(pfxPath) && File.Exists(pfxPath))
+                {
+                    return delegate { return new X509Certificate2(pfxPath, pfxPassword ?? "", flags ?? X509KeyStorageFlags.DefaultKeySet); };
+                }
+            } catch
+            { }
+            return null;
         }
         SocketMode ISocketCallback.Connected(Stream stream)
         {