Sn.exe –R “abc.dll”
-R is to resign, as I’ve kept signing on in Visual Studio, but still before gacing the dll, it has to be signed using the sn.exe.
In case there is a policy file for this dll, you may choose to sign that as well using the same key.
Note that signing is done prior to gac- ing the dll using the gacutil.exe tool
Both these tools come as a part of Visual Studio installation