Data protection ABC (1/10)

Anonymizing and pseudonymizing

§ 3 Section 6 BDSG defines Anonymisation as the alteration of personal data so that the individual details can no longer be attributed to a specific or identifiable person, or can only be attributed with a disproportionate amount of time, cost and effort (cf. Gola/Klug/Körffer 2015, p. 44).

The first variant describes absolute anonymisation, which is therefore irreversible.

The second variant describes de facto anonymisation. Although the restoration of the data and the personal reference is theoretically still possible here, it is very unlikely in practice since it would involve an extremely high effort.

The anonymisation must be distinguished from pseudonymisation. According to § 3 Section 6a of the BDSG, this refers to the "replacement of the name and other identification features by a distinctive sign for the purpose of excluding or substantially complicating the determination of the person concerned". This technique is used so that a personal reference can be established under certain conditions, namely when the assignment rule is known which determines how the pseudonymised data can again be assigned to a person (cf. Kühling/Seidel/Sivridis 2015, p. 106f.).

Example: Pseudonymisation by matriculation numbers

If one only knows the respective matriculation number, it is impossible to assign the data to a person, so that these data are now anonymous data. However, if you know the assignment key, i.e. which student owns which matriculation number, you can assign the data again.

The handover of grades with matriculation numbers, for example, is problematic from the point of view of data protection: It is likely that the students will know each other's matriculation numbers after a few semesters. Thus they then have the allocation key.

It is also conceivable to present, for example, particularly successful term papers only with the matriculation number. Here, data protection problems can be avoided by obtaining consent before publication and publishing the paper completely anonymously.