Secure integrated circuit

A security system protected against reverse engineering, comprising:

• a substrate;
• at least one integrated circuit embedded in said substrate, said integrated circuit comprising:
• a semiconductor substrate;
• at least two logic circuits of different types formed in said semiconductor substrate with layouts which make said two logic circuits look alike to a reverse engineer, each logic circuit having doped IC elements, and
• an interconnect for at least one of said elements, said interconnect comprising a dopant implant in said substrate of like conductivity to said element, and providing an electrical signal path to interconnect said element with another portion of the IC, said dopant implant being substantially not discernible by reverse engineering techniques.