Back in 2005, I was at Rochester Institute of Technology, and our ID cards encoded our student ID... which was also our social security number. The Student Government made you take attendence by student ID number for certain functions, so at one point as officer of one of the campus's major clubs I was sitting with a spreadsheet of the names and socials of >1000 students.

They were also low-cap magstripes, and the checksums were predictable. Inventive students had a database of a few all-access keycards that were used to sneak into the tunnels under the academic buildings at all hours of the night...