Hello, I have an electronic circuit that accepts 4 hex numbers and output 4 decoded hex numbers. Knowing that I have thousands of inputs and decoded outputs, I would like to know if there is a way to figure mathematically the operation done by this d

Not sure what you need exactly, but the BaseConverter can be used to convert hex to dec (base 16 to 10) or hex to bin (base 16 to 2).

Ok let's say you have thousands of records such as decode( 1923) = 2304 and decode( 8305) =9824 and so forth.... Would it be possible to figure what this decode function does exactly ?

Is the result deterministic? If the same input always gives the same result, it might be somewhere between fairly easy and doable, but if not, well, it might be somewhere between doable and impossible.

Sounds like a codebreaking challenge 😅

Yes the same input always gives the same result. I am pretty sure that the decoding goes through logical gates ( XOR, AND...) ...Now , I am still trying to find a way to figure what is the function behind this operation... I can provide thousands of records that I have saved in an excel sheet

Are you perhaps trying to break the Enigma machine? ;-)

For reference, it was indeed doable, but it's far from trivial, even with today's hardware. For your case, it depends on how much effort went in to trying to make it difficult for you. Perhaps you'll have more luck asking your question on a more dedicated forum.