Archives    About    Etc    authors    etc

On function creep, privacy and encryption


Johannes Gutenberg introduced the printing press in Europe and used his technique to efficiently produce bibles, spread the word of God, and support the authority of the Catholic Church. Instead, the introduction of efficient printing techniques in Europe “introduced the era of mass communication which permanently altered the structure of society. The relatively unrestricted circulation of information—including revolutionary ideas—transcended borders, captured the masses in the Reformation and threatened the power of political and religious authorities; the sharp increase in literacy broke the monopoly of the literate elite on education and learning and bolstered the emerging middle class” (Wikipedia ).

The technology of mechanical printing changed European civilization in spite of and beyond the intentions of its designer. And in this case, we can applaud this as something beautiful: technology has the power to redefine the boundaries of thought and action and transform our social realities for the better. This transformative power is in fact something that is sought after nowadays. Take for example the Internet of Things movement that entertains the ideal of connected technologies embedded in our homes and ultimately our cities, to the point where they are ubiquitous and shape our life world. Despite this being a dream for some, others see in this the voluntary and naive submission to a surveillance society.

Function creep and security

In other cases, the application of a technology outside of its intended context is simply inappropriate. When it comes to security, Bruce Schneier writes that “far too often we build security for one purpose, only to find it being used for another purpose – one it wasn’t suited for in the first place.” The correct functioning of a technology is not independent of the values of the social context in which they are embedded. Schneier mentions how US driver’s licences increasingly transformed from being a simple credential for showing that you know how to drive a car, to something you could use to prove you are old enough for buying liquor. With this changing social context, it suddenly became valuable to create fake driver’s licenses, and this bumped up its security needs. Another one: “Security systems that are good enough to protect cheap commodities from being stolen are suddenly ineffective once the price of those commodities rises high enough.” Security measures are always taken relative to how much time and money you expect an attacker to put in. When the value of the thing you secure goes up, your security measure goes from being appropriate to being a laughing stock.

The use of a technological design beyond its intended purpose is called function creep. This is not only a potential issue for security, but also for privacy if the function creep involves personal data. The linking of personal data from various sources can lead to a quite accurate personal profile that may lead to some convenient applications, such as a personalized search experience, but also to questionable practices such as political microtargeting , which may disrupt the democratic political process. The issue here is not just the particular usage of personal data that may be desirable or not, but that often the used data is originally collected for other purposes. The public outrage about the Cambridge Analytica-scandal is understandable because personal data collected in the context of a social network was used in another context for the Trump campaign. Those people may have consented to sharing their data with Facebook, but would likely not have consented to their data being used for a political campaign.

Function creep and contextual integrity

Why function creep is such a threat to privacy is best explained by Helen Nissenbaum’s concept of contextual integrity. When we visit a doctor we consent to disclosing very personal information so that the doctor can adequately help us (we are obliged to give the doctor complete and accurate information, actually). If you agree that this is not a privacy breach, then you should also agree that privacy is more than straight up secrecy or confidentiality. But consent in the context of the examination room does not mean that the doctor can share this information outside of this well-defined context of medical practice. You do however likely accept that the doctor may need to consult with a specialist, and consequently you give away a bit of control over your data. Privacy is thus more than confidentiality or being in full control of your data at all times. The relative importance of all these aspects of privacy are heavily context dependent, and can therefore not simply be translated from one context into another. So neither can consent.

For the course where I work as a teaching assistant, students were asked to give an example of function creep, some positive and negative implications and how to resolve the negative implications. Reading and evaluating the resulting small essays were proof of the importance of teaching, as they forced my to formulate my own thoughts on the subject. I noticed one trend in particular, namely that many students proposed encryption as a solution to the privacy issues concerning function creep.

Is encryption a solution?

Some students found a blog of Michael Zimmer where he gives an example of privacy invasion due to function creep. He mentions how a dean of a Washington high school thought he saw two girls kissing. A quick check with the footage of the surveillance camera confirmed this, and the dean consequently informed the parents of one of the girls about this. The girl got pulled out of school. The presence of a surveillance camera is acceptable for ensuring public safety, but was instead used to enforce social norms: textbook function creep (and perhaps the dean was an actual creep, who knows).

In this scenario the inappropriate function creep is caused by human interference. One proposed solution was thus the design of an autonomous AI system that encodes the used data and only extracted features relevant for its goal: e.g. ensuring public safety. Another proposal was to encrypt all collected data, so that explicit permission to use the data is always needed. Let’s leave the technical feasibility of these proposals aside for now.

These answers make sense given that they seem to assume that function creep is due to explicit human involvement (and specifically, with less than pure intentions). Encrypting data is indeed very important for protecting sensitive data against people with bad intentions that try to steal and misuse that data. But I would argue that function creep does not depend on this explicit human interference.

Good encryption ensures data protection, which is preceded by the moment of data collection. Compare how the GDPR battles function creep: before collecting data you have to specify exactly for what you intend to use it, why your need for that data is legitimate, and how long you need it. Function creep is thus already relevant at the stage of collecting data and specifying the purpose of data collection. This process of data collection can be fully automated without humans necessarily trying to make inferences on particular individuals. But the critical point is that no data is used that was legitimately recorded for another purpose, for which encryption is maybe a necessary condition but not a sufficient one. Imagine an automated AI system recording and linking data haphazardly without much oversight on the purpose of data collection. Following the first proposed solution, the AI would encrypt the collected data, protecting it against humans with malicious intent. But I would argue that in this scenario things did not get better but perhaps rather worse. The system extracts features based on data that may be inappropriately gathered and linked (function creep), and in this case encryption would even further limit the explainability of decisions made or supported by such a system.

Encryption also raises the question: Encrypted by who? Who is in control of the data? Let’s say a law obliges me to encrypt the data I gathered. Since I have the key to decrypt the data, I can still use the data when I need it, potentially for another purpose than the one I stated when I collected the data. In other words, misuse by the data controller is not necessarily counteracted by the technical measure of encryption alone. Encryption protects against misuse by other actors.

I would thus say that even though encryption is extremely important for data protection, it does not in itself prevent function creep. However, that does not mean that encryption cannot help battling function creep. The app IRMA, developed by the Privacy by Design foundation offers attribute-based authentication with zero-knowledge proofs in a way that is sensitive to contextual integrity. (They have very strong ties to Radboud University, but I am in no way affiliated.) I can for example load the attribute that I’m an inhabitant of Nijmegen from the local municipality into IRMA. If I need to authenticate to an application that needs to know where I live, I can prove that I indeed own this attribute without disclosing any other attributes, such as my age. Likewise, I can prove that I’m older than 18 to another application, without having to disclose my exact age (zero-knowledge proof) or disclose where I live (irrelevant attribute). The context sensitivity thus lies therein that the user remains in control of which attributes to disclose in each particular context and only in that context, without having to give away more information.

Such use of encryption addresses the two main points I thought the above answers on encryption missed. Firstly, IRMA is sensitive to contextual integrity because it uses cryptography to ensure only relevant attributes are used, for which the purpose of original collection matches the legitimate use case of the app. Secondly, this use of encryption is effective against function creep only by giving the user control over identity management and the authentication process in a decentralized manner.

This does not solve issues with surveillance of course, but was the first thing that came to my mind when thinking about a way in which encryption might help to battle privacy-invading function creep. Privacy by design is a good example of how encryption can be used effectively against function creep by embedding the relevant ethical and societal values in a responsible design practice.

Secondary sorting in Python <-- Latest

Friendship, death, and writing in Michel de Montaigne's Essays <-- Random


Do you want to link a webmention to this page?


Joeri on Wednesday, Nov 13, 2019:

Interesting subject! I had not heard of the term function creep, although I have been confronted with this topic many times.

In cancer medicine (my field of work), patients give consent to perform tests in order to adequately diagnose the cancer type and risk stratification (clinical setting). For instance, this includes imagining like CT- and MRI-scans. After the patients is treated, these scans are preserved for many many years in which they might be used for retrospective research. Also, these images are sometimes used in presentations at symposia.

I have to admit that I do not know when patients give consent to future research or in what way they are informed (by leaflet? by the physician?). I also feel that simply telling the patient that their images or blood test may be used for research, does not tell them for what cause or what specific research question is addressed. In prospective research, the patient always receives information about the test.

I think this might be yet another example of function creep. This time, the creep exists because it is so difficult to explain to a patient all the million ways that their data may be used in future studies. If it were possible to fully inform the patient, or the logistical problem of asking a patient whether their data may be used of a retrospective analysis when they are no longer in the hospital can be overcome, then I guess you would say that the data is multifunctional to begin with, rather than speaking of function creep.

I think this is more a discussion on informed consent than on function creep. Maybe, a query could be send with an app to the individual asking if their data may be used for so an so research, giving the individual user control. This way, a new consent could be given more easily, tackling the logistical problem.

Nevertheless, in medicine, the problem of integrity has already started when the researcher approaches the individual since the medical data had to be accessed for selection. How to prevent privacy-invading function creep in this scenario?

Finally, I also think many physicians consider using data, obtained in the clinical setting, is harmless to the patient when data anonymization is thorough. However, that is a whole different discussion.

Edwin on Wednesday, Nov 13, 2019
In reply to Joeri

Great reply! You raise interesting points.

Medical data is a story of its own and I’m not a professional, but here are my initial thoughts:

It is indeed hard to fully predict in advance the specific details of how data will be used in retrospective analysis. But if there is initial patient-doctor contact where a patient consents to their data being used for research, then at least it is clear to me that those future uses have the same underlying purpose as what the data was collected for: furthering medical science. So I don’t think that’s function creep, and I agree with you the main issue there is informed consent.

There is an interesting power dynamics there though! The underlying question is always: when is consent meaningful? Very ill patients, such as people with cancer that have a serious chance of dying, might consent to a lot more than they would if they were healthy. This makes them extra vulnerable for privacy-related issues.

Normally genetic data, uniquely identifying biometric data or data concerning health, sex life or sexual orientation cannot be processed at all according to Article 9 of the GDPR. But the medical sector is mentioned as a clear exemption to this prohibition here! In general, privacy is not an absolute right and is always weighed against other factors that may overrule it. For example, normally people have the right to request deletion of their personal data, but in some medical cases this can be overruled if that’s in the benefit of public health. That’s something to be evaluated on a case by case basis, I think.

At this link I found this clarification w.r.t. consent for medical research:

In research within the scope of the Medical Research Involving Human Subjects Act ( “WMO”) explicit consent is already asked from the subjects for the processing of their personal data in the context of the study. This is done on the basis of a corresponding text in the Subjects Information Form ( “PIF”) and the informed consent form. This is consent is asked separately from the consent for participation in the study that is required by the WMO. Consent for the processing of personal data must be explicitly asked and is not implied by or can not be derived from the consent for participation in the study. (…) It is not necessary to ask subjects who participate or have participated in approved studies within the scope of the WMO for re-consent for the processing of their personal data

This does indeed assume that you appropriately (pseudo-)anonymize the data.

What is an example of breached contextual integrity are doctors having a peek at patient dossiers while these doctors are in no way involved in the medical treatment. This was actually in the news this year.

One more remark about your idea for an app: that would in my opinion actually make function creep more likely. A philosopher that currently works in Nijmegen published a worthwhile article on the Googlization of health research. Using apps is a highly effective way of tricking people into given away data about themselves, that can subsequently be used for health research. This article on the involvement of Google in healthcare was actually published yesterday. Here as well. Google will store health care data of 150 hospitals! Do we trust Google, of all companies, with that sensitive data? A hot topic!

Hope these thoughts are helpful in the context of your own work! (Btw… these comments combined are long enough for a new post…)

Joeri on Sunday, Nov 17, 2019:

Thank you for the reply Edwin. Interesting thoughts that are definitely reflective on my own work.

As a little addendum, I found the following statement in the ‘Human Tissue and Medical Research: Code of Conduct for responsible use’:

“For ‘further use’ in scientific research of coded-anonymous human tissue, an augmented system of ‘opt-out’ is deemed acceptable (…) no-objection or opt-out expresses citizenship, namely that participation is a fundamental contribution to results of research becoming available for others. At the same time it leaves enough room to withdraw should the feeling exist that scientific research with human tissue (or data) should not take place.”

This means that as by default, tissue that is left-over from the clinical setting, may always be used for research purposes, since the benefit of the population as a whole should be the concern of every citizen. The opt-out principle allows for user control.

This is similar to what you found in the WMO.

Again, thanks for the interesting subject and our little digression!

Leave a comment

Thank you



Something went wrong!
