Shares Users' User IDs with Third Parties
A Closer Look at - Ben Edelman

This page shows how shares users' user IDs with third parties. Further discussion. Prints Users' ID Numbers On Coupons

Every coupon printed from bears a series of small numbers around its four edges. These numbers include the user ID of the user who printed the coupon. The example coupon below was printed on my computer. Notice the repeated "35415364" -- my user ID. Further discussion. Allows Third-party Web Sites to Retrieve User ID Numbers

Any web page can invoke the "GetDeviceID" method of's coupon-printing software. The web page then receives the user ID associated with the user's installation of software. The screenshot below shows confirmation via a demonstration page I wrote. Notice that the demonstration page -- part of my site, -- is able to retrieve my user ID. Notice also that this user ID matches the number shown on the face of each printed coupon (e.g. in the example above). Further discussion.'s Veri-fi site lets any third party check whether a given user has printed a given coupon's Veri-fi site lets any interested person check whether a given user has printed a given coupon. Using Veri-fi requires only entering a user ID (widely available both in print and through JavaScript, as shown above) and a coupon ID (available from any other coupon). The first screenshot below shows the simple process of entering the required information.


If the specified user has printed the specified coupon (i.e. the coupon is "valid"), shows a message to that effect.


If the specified user has never printed the specified coupon, calls the coupon "invalid."