1. A data repository system that can securely guarantee a privacy policy of a user, comprising: an initialization system, wherein the initialization system includes: a system for providing the user with a privacy policy of the data repository and a mechanism for validating the privacy policy of the data repository, and a system for collecting user data from the user, wherein the user data comprises a description of validity tokens authorizing a third party access to a subset of the user data from the data repository; and a referral system for providing the third party access to the subset of the user data, including: a system for checking that a privacy policy of the third party is compatible with the privacy policy of the user, and a system for digitally encoding the subset of data.