Enabling operator controls for machine operation

A machine, comprising:

• a plurality of operator controls enabled, in an operation mode, to operate the machine, and, in a validation mode, disabled to operate the machine and selectable to provide inputs for a candidate key;
• a computing device communicatively coupled to the operator controls, wherein the computing device is programmed to:
• initialize the validation mode, including initializing the candidate key and an input multiplier, wherein the input multiplier is initialized according to a number base, and a maximum storage length, of a stored key;
• receive a plurality of inputs to the operator controls in the validation mode;
• determine respective numeric values of the inputs;
• add the candidate key to a product of the multiplier and the numeric value of a first input to update the candidate key;
• for each of one or more second inputs to the operator controls after the first input to the operator controls, determine whether the candidate key matches the stored key;
• and
• upon determining that the candidate key matches the stored key, output an authorization.