How to separate a person's identity from his personal data?

Question

I\'m writing an app which main purpose is to keep list of users purchases.

I would like to ensure that even I as a developer (or anyone with full access to the database)

Answer 1

Keep in mind that even without actually storing the person's identifying information anywhere, merely associating enough information all with the same key could allow you to figure out the identity of the person associated with certain information. For a simple example, you could call up the strip club and ask which customer drove a Ferrari.

For this reason, when you de-identify medical records (for use in research and such), you have to remove birthdays for people over 89 years old (because people that old are rare enough that a specific birthdate could point to a single person) and remove any geographic coding that specifies an area containing fewer than 20,000 people. (See http://privacy.med.miami.edu/glossary/xd_deidentified_health_info.htm)

AOL found out the hard way when they released search data that people can be identified just by knowing what searches are associated with an anonymous person. (See http://www.fi.muni.cz/kd/events/cikhaj-2007-jan/slides/kumpost.pdf)