Michael Grünewald recently posted this comment:
A very important method you do not mention is the “four-eyes principle” which is used in the finance – either as a regulatory obligation or as a safe-guard. In the software industry it is implemented in various ways, as e.g. code reviews but also can be used to validate commands affecting live systems.
Correct me if I'm wrong, but I was taught that the "four-eyes principle" is about something that is "approved to happen", after at least 2 human beings (and/or automated processes) gave their prior blessing. Or to use the (slightly corrected) wording about the "two-(wo)man rule" from Wikipedia:
The two-man rule is a control mechanism designed to achieve a high level of security for especially critical material or operations. Under this rule all access and actions requires the presence of two authorized people at all times.
Regulatory obligations are, pretty sure, off topic here, but in the context of "safe-guard", what are the possible conceptual implementations of this four-eyes principle, which probably could apply to any platform / OS / hardware being used?