Thanks for the response. I am able to register and also created Workflow and it is not throwing any exception. My role is System Administrator and System Customizer so I have full rights to share the records too.
Please find the steps which I follows:
1. Registered the assembly.
2. Created a new Workflow (without specifying any Event) on Account entity.
3. Added the steps Utilities: Shared Record.
4. Set properties as follows: a) Share user 1 = my name, b) Read Permision = False, c) Write Permission = False.
And then tested this.
But, still I am able to read and write any Account record.
Once again thanks for the quick response.