To protect assemblies from unauthorised changes they need to be signed with a strong name key. Strong name is valuable in guaranteeing the uniqueness of the assembly. A signed assembly can also be registered in the GAC.
How to sign an assembly?
To sign an assembly first generate a public/private key pair with the sn.exe utility:
sn.exe –k KeyPair.snk
Then you use Visual Studio project properties screen to sign the assembly with the snk file generated above.