A decoder comprises a feedback shift register having a plurality of register elements that implement a simplex code and take a register vector for determining an appropriate syndrome fed into the feedback shift register and stored in the plurality of register elements. A combination device algebraically combines a subset of the register elements and provides a combination result vector. A majority decision-making unit ascertains a most frequently occurring value within the combination result vector and provides it as a decision result. An input selector connects an input of the feedback shift register to an input interface arrangement or to an output of the majority decision-making unit, and provides an input vector by the input interface arrangement and corresponds to the ascertained form of the physical unclonable properties as a register vector and, and provides a decision vector comprising the decision result and further decision results as a register vector.