Signature Error

I'm putting together a demo for signing a stored procedure and I'm coming up blank as to why it is failing. Below is the code:



USE master

GO

--Create a pair of logins

CREATE LOGIN TestLogin WITH PASSWORD = 'P@55w0rd'

GO

CREATE LOGIN DummyLogin WITH PASSWORD = 'P@55w0rd'

GO

--Create a demo database

CREATE DATABASE SignatureDemo

GO

USE SignatureDemo

GO

--Create a low privileged user in the database

CREATE USER TestLogin FOR LOGIN TestLogin

GO

CREATE USER DummyLogin FOR LOGIN DummyLogin

GO

CREATE SCHEMA Test AUTHORIZATION DummyLogin

GO

--Create a dummy table and add data to it

CREATE TABLE Test.MyTable

(ID INT IDENTITY(1,1),

TestVal VARCHAR(10) NOT NULL)

GO

INSERT INTO Test.MyTable

(TestVal)

VALUES ('Test1')

GO

INSERT INTO Test.MyTable

(TestVal)

VALUES ('Test2')

GO

--Create a procedures to access test table

CREATE PROCEDURE Test.asp_Proc1

AS

SELECT ID, TestVal FROM Test.MyTable

GO

CREATE PROCEDURE dbo.asp_SignatureTest

AS

EXEC Test.asp_Proc1

GO

GRANT EXECUTE ON dbo.asp_SignatureTest TO TestLogin

GO

--Verify that TestLogin can not select from the table

EXECUTE AS LOGIN = 'TestLogin'

EXEC asp_SignatureTest

REVERT

GO

--Create a database master key

CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'P@55w0rd'

GO

CREATE CERTIFICATE TestCert WITH SUBJECT = 'Test Certificate'

GO

--Sign the procedure, remove the private key, and backup to a file

ADD SIGNATURE TO Test.asp_Proc1 BY CERTIFICATE TestCert

GO

ALTER CERTIFICATE TestCert REMOVE PRIVATE KEY

GO

BACKUP CERTIFICATE TestCert TO FILE = 'TestCert.cer'

GO

--Create a user in the database mapped to the certificate

CREATE USER CertLogin FROM CERTIFICATE TestCert

GO

--Grant permissions to the user

GRANT EXECUTE ON Test.asp_Proc1 TO CertLogin

GO

--Verify that TestLogin can now select from the table (I'm still receiving an execute permissions error on Test.asp_Proc1 for some reason.)

EXECUTE AS LOGIN = 'TestLogin'

EXEC asp_SignatureTest

REVERT

GO

USE master

GO

DROP DATABASE SignatureDemo

DROP LOGIN TestLogin

DROP LOGIN DummyLogin

DROP LOGIN CertLogin

DROP CERTIFICATE TestCert

GO