There is a way to add strong name to an existing dll.
All you need is sn.exe, ildasm.exe and ilasm.exe
These are .NET Framework tools designed by Microsoft: https://learn.microsoft.com/en-us/dotnet/framework/tools/ .
To run these tools, use the Developer Command Prompt for Visual Studio.
Step 1:
You should create a key file using sn.exe:
sn.exe -k C:\IAmWorkingHere\KeyFile1.snk
A KeyFile1.snk was created to C:\IAmWorkingHere folder. We will use it in step 3.
Step 2:
Use ildasm.exe to "extract" IL code, resources etc. from the dll.
ildasm.exe /out c:\IAmWorkingHere\RestSharp.il
It is depending on your RestSharp version, but for me 2 file was created a RestSharp.il file that contains the IL Code in text format, and a RestSharp.res file that contains the resource information of the dll.
Step 3
(Rename the original RestSharp.dll if you want to keep it safe) and use ilasm.exe to create your strong named RestSharp.dll
ilasm.exe c:\IAmWorkingHere\RestSharp.il /dll /key=c:\IAmWorkingHere\KeyFile1.snk /resource:c:\IAmWorkingHere\RestSharp.res
And your strong named RestSharp.dll was created.
I hope it is help.