CryptoCAN
CryptoCAN from Canis Labs is the only encryption scheme specifically designed for CAN to meet the following requirements for CAN communications:
Fit a publish-subscribe model
Encrypted messages must have bounded latencies
Fit within 8-byte CAN frames
Work on microcontrollers with limited resources
Support fast-start communications
CryptoCAN takes a standard CAN frame (the plaintext frame) and converts it into a CryptoCAN message (the ciphertext message) that is sent on CAN then converted back into the original plaintext CAN frame by each receiver.
A CAN frame is converted into two CAN frames containing the encrypted original payload and a message authentication code (MAC). (Coupled with SmartCan, only one frame is required resulting in significantly more available bandwidth.) These are then decoded back to the plaintext frame at each receiver. The MAC is used to protect the ciphertext message from tampering.
To allow CAN devices using microcontrollers without hardware security modules (HSMs) to participate in secure communications, CryptoCAN has a layered architecture and includes a software emulated HSM.
The CryptoCAN stack with an HSM emulated in software and key storage in local non-volatile memory.
The pure software stack is included in MicroPython firmware for the CANPico, with keys stored in the Pico’s flash memory. The CANPico is a platform primarily intended for evaluation and prototyping. Depending on the threat model, the software HSM may be appropriate for deployment.