4 KeeLoq Technology

Microchip Technology stands as a major supplier in the security industry. Our use of the proprietary KeeLoq technology is instrumental in enhancing security across various applications for leading manufacturers worldwide.

KeeLoq technology is a code-hopping technology, which means that each transmission is unique with changes occurring at every button press. The core of this technology involves a counter that increments with each button press, followed by the addition of an encryption layer to the packet. This system operates on an event-driven basis, where the event corresponds to the pressing of a button on the transmitter. In the extended implementation of the ultimate KeeLoq technology, a timer replaces the counter. This timer runs at the same rate as a corresponding timer on the receiver side.

The following shows a comparison table with all available KeeLoq technology implementations.

Table 4-1. KeeLoq Technologies

KeeLoq® Technology

Security Level

Encryption/Decryption Engine

Encryption/Decryption Key Length

Transmission Length

Synchronization

Classic KeeLoq technology

Medium

Non-linear Feedback Shift Register (NLFSR)

64 bits

66 bits

Counter

Advanced KeeLoq technology

High

Advanced Encryption Standard (AES)

128 bits

168 bits

Counter

Ultimate KeeLoq technology

High

AES

128 bits

192 bits

Counter + Timer