Same attribute with different prefix-constant values

[Peter Schober]

* lalithj <j_lalith at hotmail.com> [2015-03-18 03:41]:
> Currently from our IdP, we do pass the employeeNumber attribute to different
> SPs, value of the attribute got the format 
> f<employee Number>
> 
> However we got two more SPs, asking for the same attribute but with two
> different constant values e.g.
> g<employee Number>

Stating the obvious: Why not simply release employeeNumber verbatim to
each SP? The same constant character for each and every subject of
your employees doesn't convey any information the SP couldn't get from
other facts, e.g. the issuer of the assertion or another abstracted
identifier for the organization.

As for your question how specifically you'd transform one attribute
value to another, in this case the Template attribute definition is
probably easiest:
https://wiki.shibboleth.net/confluence/display/SHIB2/ResolverTemplateAttributeDefinition
But Script and Regex would work too, of course.

Teaching a man how to fish:
Documentation Home -> Configure -> IdP Add Attribute:
https://wiki.shibboleth.net/confluence/display/SHIB2/IdPAddAttribute
-peter