Adds a package sign step

Author: daveaglick

build.cake

@@ -134,6 +134,23 @@ Task("Pack")
             Symbols = false
         });
     });
+    
+Task("Sign")
+    .IsDependentOn("Pack")
+    .WithCriteria(() => isLocal)
+    .Does(() =>
+    {
+        var certPass = EnvironmentVariable("DAVIDGLICK_CERTPASS");
+        if (string.IsNullOrEmpty(certPass))
+        {
+            throw new InvalidOperationException("Could not resolve certificate password.");
+        }
+
+        foreach (var nupkg in GetFiles($"{ buildDir }/*.nupkg"))
+        {
+            StartProcess("nuget", "sign \"" + nupkg.ToString() + "\" -CertificatePath \"davidglick.pfx\" -CertificatePassword \"" + certPass + "\" -Timestamper \"http://timestamp.digicert.com\" -NonInteractive");
+        }        
+    });
 
 Task("Zip")
     .Description("Zips the build output.")
@@ -155,7 +172,7 @@ Task("Zip")
 
 Task("NuGet")
     .Description("Pushes the packages to the NuGet gallery.")
-    .IsDependentOn("Pack")
+    .IsDependentOn("Sign")
     .WithCriteria(() => isLocal)
     .Does(() =>
     {