Automotive Diagnostics — Secured Data Transmission

This service is used when there has to be any secured data communication between the server/ECU and the client/Tester. The purpose is to protect any confidential data against attacks from threats/ vulnerabilities

Important points about Secure data Transmission

• Only confirmed services can use this service. Unconfirmed services cannot use this service such as

1. Response On Event (0x86)
2. Read Data by Protected Identifier (0x2A)
3. Tester present (0x3E)

• The secure data transmission must be a point-to-point communication. So, functional addressing cannot be used and only physical addressing can be used ( We will learn more about this in the coming days)
• Because, there is physical addressing only supported, only one server/ECU would be involved from a client
• The cryptographic layer, also called as security sub-layer checks the decrypted message for any service to be performed on the secured data and requests the system application module to perform the service on confirmation of the received message

Examples for message flow

Consider a scenario where the client is initiating a secured data transmission(0x10) to the ECU

Request message

Positive Response message

Negative Response Message

Supported Negative response codes