Logging in to External Site from My Site

[mwa]

My organization has an Employee Portal of sorts to retrieve paystubs, benefits info, w2's, etc.. The Portal was written in Asp.net 1.1 using Forms Authentication.

We have just recently contracted with an outside vendor to provide some services to our employees. What we would like to do is have employees login to our Employee Portal using their credentials. Then have the employee click a link that redirects the user to the vendor's site. This external site requires the user to login again (with a different user id/password). What we would like to do is eliminate that secondary login. We would like to somehow pass credentials from our Portal over to the Vendor, and have the employee auto logged in to their site. The vendor is amenable to making changes, but I need to know the best way to handle this.

Any thoughts/links/direction would be appreciated.

Thanks!

mwa
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[jbenson001]

encrypte the un/pw and pass them to the other site, then have them decrypt.

 

[mwa]

That would mean I'd have to provide them with a file of our User ID's and Pwd's. Not sure I want to do that.

What about passing a GUID that represents a user ID, then write a web-service that they can call to check the GUID and retrieve the user?

mwa
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[jbenson001]

Why would you have to send them a list of UN/PWs?
Let them decrypt what you pass them and call a webservice or WCF rest service that will validate the user.