Medical ethics committees have ethicists, but the main advice is from medical experts. I would not want anybody else judging the ethics of medical experiments, as no one else has the expert knowledge. I see absolutely no reason why this should different for computer scientists and cryptographers.

No one else understands the implications of an experiment or a new methodology. I was at a meeting recently discussing ethics committees for computer science. A medical expert gave his opinion and said (paraphrasing): I fail to see the problem with digitalisation, we have had medical records on paper for years, now they are on a computer, what is the difference?

I don't mean to say that every scientist should do this individually. They should discuss this with colleagues, and with an ethics committee, which should contain subject matter experts, but also ethicists.