CAN E2E (End-to-End) Protection Example

Overview

This example demonstrates how to implement End-to-End (E2E) protection for CAN messages using CRC8 checksum and sequence counter. E2E protection is a safety mechanism commonly used in automotive systems to detect message corruption, loss, or replay attacks.

E2E Protection Mechanism

The example implements a simple E2E protection scheme where:

• Byte 6: Contains a sequence counter (0-255, wraps around)
• Byte 7: Contains a CRC8 checksum computed over bytes 0-6

This ensures that:

1. Message sequence can be tracked (counter)
2. Message integrity can be verified (CRC8 checksum)
3. Missing or corrupted messages can be detected

Code Example

import {CRC, setTxPending} from 'ECB'

let cnt=0;
const crc8=CRC.buildInCrc('CRC8')!
setTxPending((msg)=>{
    if(msg.id==1&&msg.data.length==8){
        msg.data[6]=(cnt++)%256;
        msg.data[7]=crc8.compute(msg.data.subarray(0,7))
        return msg.data
    }else{
        return msg.data
    }
})

How It Works

1. CRC8 Initialization: Creates a CRC8 calculator using the built-in CRC module
2. Message Interception: Uses setTxPending to intercept all outgoing CAN messages before transmission
3. E2E Protection: For messages with ID 1 and 8-byte length:
   • Updates byte 6 with an incrementing counter (modulo 256)
   • Computes CRC8 checksum over bytes 0-6
   • Writes the checksum to byte 7
4. Message Transmission: Returns the modified message data for transmission