A hardware backdoor is a backdoor implemented within the physical components of a computer system, also known as its hardware. They can be created by introducing malicious code to a component's firmware, or even during the manufacturing process of a integrated circuit, known as a hardware trojan.[1][2] Often, they are used to undermine security in smartcards and cryptoprocessors, unless investment is made in anti-backdoor design methods.[3] They have also been considered for car hacking.[4]