In what companies can I find internship/job in information security?

I am a computer science master's student from Europe, majoring in information security and looking for an internship.

The problem is that I have no idea what jobs there are in what kinds of companies in information security.

I am very interested in almost all aspects of information security, but I am most interested in the theoretical parts, such as cryptography and formal methods of information security. Does anybody know of any jobs/companies where one has the opportunity to formally proof properties about a system, model systems to find attacks automatically, analyse/develop new cryptographic protocols or any similar thing? Or does anybody have advice what other jobs there could be in information security if one does prefer to not be programming all day?

I am very thankful for any hint!