A tamper-proof structure for protecting an electronic module, comprising a pattern of signal lines having a highly unpredictable layout, which is an approximation of a space-filling curve obtained by the replication of at least one elementary space element having an inscribed base curve inscribed therein. The base curve is adapted, by replication of the elementary space element, to generate an approximation of an at least two-dimensional space-filling curve, the replication being such that an end of the base curve in one elementary space element is connected to the end of the base curve in another, adjacent elementary space element of the replication.