How do you say 黑箱作业 in English? It is literally translated as ”black-box operation(s)”.

It refers to actions within an organization which are not transparent to the general public or the “masses” within the organization, which consequently result in bad things happening. It is a metaphor of the black box, where one knows the input and the output, but doesn’t know the underlying process/transformation that occurred to change the input into the output.

Is there an idiom in English that encapsulates the same idea?
The term &quot;黑箱&quot; was a direct translation of a science term &quot;Black box&quot; from English

&quot;Black box is a device, system or object which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings.
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Almost anything might be referred to as a black box: a transistor, an engine, an algorithm, the human brain, an institution or government.

黑箱作业 in English should be ”black-box operation(s)” . (you can see what goes in and what comes out, but you never how the system works). Presuming the English speaker knows what is a 'black box'