Welcome to Module Signing Info, a site devoted to working with Module Signing, Certificates, and Asymmetric Keys in Microsoft SQL Server.

Module Signing is using Asymmetric Keys and/or Certificates to add fine-grained permissions to Stored Procedures, Triggers, Assemblies, and User-Defined Functions (except Inline Table-Valued Functions). Doing this allows you to effectively create highly specific permissions and avoid opening up security holes such as:

• using impersonation (i.e. EXECUTE AS)
• enabling "cross-database ownership chaining"
• enabling TRUSTWORTHY
• disabling "clr strict security" (new in SQL Server 2017)

To learn more about why you should use Module Signing instead of those other methods, please read: PLEASE, Please, please Stop Using Impersonation, TRUSTWORTHY, and Cross-DB Ownership Chaining