Jump-proof electrical disenabling system

An anti-theft system for a protected system which has at least one essential electrical sub-system said anti-theft system comprising:

• (a) an electronically controlled gate-acting element interposed in said sub-system and operable between a closed mode permitting normal operation of said sub-system and an open mode disenabling said sub-system;
• (b) an electronic key and a receptacle to receive said key, said key containing a pre-determined code and being capable of reproducing said code as a coded chain of electrical pulses and delivering said chain of pulses to said receptacle;
• (c) a decoder electrically coupled to said receptacle for receiving said coded chain and producing an enabling signal to said gate-acting element whereby the latter is thrown into its closed mode and said sub-system is restored to normal operating capacity;
• (d) wherein said key contains a precoded shift register and said decoder includes a second shift register electrically coupled through said receptacle to said pre-coded shift register, and including an electronic clock electronically coupled to said precoded shift register through said receptacle to said second shift register to simultaneously deliver a stepping pulse to both registers to effect the shift of said coded chain of electrical pulses from said pre-coded shift register to said second shift register.