Intel MPI on Windows Authorization questions

Hi,

I am running Intel MPI on my laptop with Windows Vista. I am now a little confused regarding the authorization process, and hope someone could help me with it.

First, I am able to avoid giving credentials each time I run a MPI program by registering myself using wmpiregister. However, it seemed that I could achieve the same thing by setting I_MPI_AUTH_METHOD=delegate. How does this variable work and is it secure?

Also, it seemed that if I use -localroot, I will not be asked for password either even if I_MPI_AUTH_METHOD=password. Why does this happen? Is it because that by using -localroot, I am able to bypass the SPMD daemon?

Thanks.