Re: Global unique identifier

["Christopher Williams" <ccwilliams@xxxxxxxxxxxx>]

There aren't many details about a person that can be assumed to be constant
(not even his / her name).  Certainly not his subject name as that
presumably changes when the person changes job.  The US has a social
security number; other countries have similar schemes (I have a unique
National Insurance number).  If there are privacy issues surrounding the use
of these values, use a SHA-1 hash of the value instead.