If you want to do a bachelor thesis in Digital Security but are not sure what topic you'd like and whom to ask as supervisor, then you can contact me, and I'll help you on your way!
You can send me an email (awesterb at cs.ru.nl), or walk by.
Before contacting me, please read the general advice below.
The easiest way to find a bachelor thesis topic is to see if you like one of the topics advertised by my colleagues.
You can, of course, also build on (or draw inspiration from) one of the previous bachelor theses.
If none of the advertised topics are to your liking, the best way to find a topic is to talk to a potential supervisor whose research or teaching you like.
If you don't know where to start, browse through the list of potential supervisors here, and if someone's research topics intrigues you, take a look at their website and papers. If you're excited to learn more, but have lots of questions, just ask them in person. Most researchers are very happy to talk about their own research!
When you mention that you're looking for a bachelor thesis, they may have some topics in mind based on your discussion, or might refer you to someone else.
Don't put all your eggs in one basket; talk to multiple potential supervisors.
You might have your own topic in mind already. In that case you must find a supervisor that is willing and able to supervise you, which can be difficult, depending on the topic.
In that case your best bet is to be as concrete as possible (“I want to see if this vulnerability works on this software too” instead of “I want to hack this software”.)
You could even consider writing a one-page bachelor thesis proposal. Don't think that you are pinning down your research this way; your bachelor thesis mind end up complety different. But by writing such a proposal, you are showing what type of research you want to do. It makes it easier for a potential supervisor to assess whether the topic is too hard, or too easy, and whether they (or someone else) can help you with it.
Doing your bachelor thesis at a company (or other external party) is possible, but not recommended. Again, it's best to contact a potential supervisor first, preferably one that has supervised students at that (or a similar) company before.
If you have already made up your mind about a topic, it's up to you to find and sell it to a potential supervisor. Again, you might want to write a short proposal.
What we're looking for in such a proposal is that the work you will be doing at the company has enough academic value (and not just value to the company), and that the company will provide enough direction to the research. In this case, the internal supervisor will generally only help you put your results to paper, and not with the research itself.