DoIP v3 TLS Certificates Generation Guide

This document describes how to generate TLS certificates and keys for DoIP v3 secure communication using OpenSSL.

Overview

DoIP v3 uses TLS (Transport Layer Security) to encrypt diagnostic communication between the tester (client) and ECU/vehicle gateway (server). The following certificates need to be generated:

CA (Certificate Authority): Root certificate used to sign both server and client certificates
Server Certificate: Used by DoIP entity (ECU/Gateway) to authenticate itself
Client Certificate: Used by diagnostic tester to authenticate itself (mutual TLS)

Directory Structure

doip-certs/
├── ca/
│   ├── ca.key          # CA private key
│   └── ca.crt          # CA certificate
├── server/
│   ├── server.key      # Server private key
│   ├── server.csr      # Server certificate signing request
│   └── server.crt      # Server certificate
└── tester/
    ├── tester.key      # Tester private key
    ├── tester.csr      # Tester certificate signing request
    └── tester.crt      # Tester certificate

Step-by-Step Commands

1. Create Directory Structure

bash

mkdir -p doip-certs/ca doip-certs/server doip-certs/tester
cd doip-certs

2. Generate CA (Certificate Authority)

The CA is the root of trust. Both server and tester certificates will be signed by this CA.

bash

# Generate CA private key (4096 bits RSA)
openssl genrsa -out ca/ca.key 4096

# Generate self-signed CA certificate (valid for 10 years)
openssl req -new -x509 -days 3650 -key ca/ca.key -out ca/ca.crt \
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP/CN=DoIP-CA"

Purpose:

ca.key: CA's private key, must be kept secure. Used to sign other certificates.
ca.crt: CA's public certificate, distributed to both server and tester for trust verification.

3. Generate Server Certificate (DoIP Entity / ECU / Gateway)

The server certificate is used by the DoIP entity to prove its identity to connecting testers.

bash

# Generate server private key (2048 bits RSA)
openssl genrsa -out server/server.key 2048

# Create server certificate signing request (CSR)
openssl req -new -key server/server.key -out server/server.csr \
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP-Server/CN=doip-server"

# Sign server certificate with CA (valid for 1 year)
openssl x509 -req -days 365 -in server/server.csr -CA ca/ca.crt -CAkey ca/ca.key \
    -CAcreateserial -out server/server.crt

Purpose (Server Side):

server.key: Server's private key, used for TLS handshake encryption. Must be kept on the server only.
server.csr: Certificate Signing Request, temporary file used during certificate generation.
server.crt: Server's public certificate, sent to clients during TLS handshake to prove identity.

Files needed on Server:

server.key - Private key for decryption
server.crt - Certificate to present to clients
ca.crt - To verify client certificates (for mutual TLS)

4. Generate Tester Certificate (Diagnostic Tester / Client)

The tester certificate is used for mutual TLS authentication, allowing the server to verify the tester's identity.

bash

# Generate tester private key (2048 bits RSA)
openssl genrsa -out tester/tester.key 2048

# Create tester certificate signing request (CSR)
openssl req -new -key tester/tester.key -out tester/tester.csr \
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP-Tester/CN=doip-tester"

# Sign tester certificate with CA (valid for 1 year)
openssl x509 -req -days 365 -in tester/tester.csr -CA ca/ca.crt -CAkey ca/ca.key \
    -CAcreateserial -out tester/tester.crt

Purpose (Tester Side):

tester.key: Tester's private key, used to prove ownership of the certificate.
tester.csr: Certificate Signing Request, temporary file used during certificate generation.
tester.crt: Tester's public certificate, sent to server for mutual authentication.

Files needed on Tester:

tester.key - Private key for authentication
tester.crt - Certificate to present to server
ca.crt - To verify server certificate

Complete Script

Here's a complete script to generate all certificates:

bash

#!/bin/bash

# Create directories
mkdir -p doip-certs/ca doip-certs/server doip-certs/tester
cd doip-certs

echo "=== Generating CA ==="
openssl genrsa -out ca/ca.key 4096
openssl req -new -x509 -days 3650 -key ca/ca.key -out ca/ca.crt \
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP/CN=DoIP-CA"

echo "=== Generating Server Certificate ==="
openssl genrsa -out server/server.key 2048
openssl req -new -key server/server.key -out server/server.csr \
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP-Server/CN=doip-server"
openssl x509 -req -days 365 -in server/server.csr -CA ca/ca.crt -CAkey ca/ca.key \
    -CAcreateserial -out server/server.crt

echo "=== Generating Tester Certificate ==="
openssl genrsa -out tester/tester.key 2048
openssl req -new -key tester/tester.key -out tester/tester.csr \
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP-Tester/CN=doip-tester"
openssl x509 -req -days 365 -in tester/tester.csr -CA ca/ca.crt -CAkey ca/ca.key \
    -CAcreateserial -out tester/tester.crt

echo "=== Verifying Certificates ==="
echo "Server certificate:"
openssl verify -CAfile ca/ca.crt server/server.crt

echo "Tester certificate:"
openssl verify -CAfile ca/ca.crt tester/tester.crt

echo "=== Done ==="

PowerShell Script (Windows)

powershell

# Create directories
New-Item -ItemType Directory -Force -Path "doip-certs/ca", "doip-certs/server", "doip-certs/tester"
Set-Location doip-certs

Write-Host "=== Generating CA ===" -ForegroundColor Green
openssl genrsa -out ca/ca.key 4096
openssl req -new -x509 -days 3650 -key ca/ca.key -out ca/ca.crt `
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP/CN=DoIP-CA"

Write-Host "=== Generating Server Certificate ===" -ForegroundColor Green
openssl genrsa -out server/server.key 2048
openssl req -new -key server/server.key -out server/server.csr `
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP-Server/CN=doip-server"
openssl x509 -req -days 365 -in server/server.csr -CA ca/ca.crt -CAkey ca/ca.key `
    -CAcreateserial -out server/server.crt

Write-Host "=== Generating Tester Certificate ===" -ForegroundColor Green
openssl genrsa -out tester/tester.key 2048
openssl req -new -key tester/tester.key -out tester/tester.csr `
    -subj "/C=CN/ST=Shanghai/L=Shanghai/O=EcuBus/OU=DoIP-Tester/CN=doip-tester"
openssl x509 -req -days 365 -in tester/tester.csr -CA ca/ca.crt -CAkey ca/ca.key `
    -CAcreateserial -out tester/tester.crt

Write-Host "=== Verifying Certificates ===" -ForegroundColor Green
openssl verify -CAfile ca/ca.crt server/server.crt
openssl verify -CAfile ca/ca.crt tester/tester.crt

Write-Host "=== Done ===" -ForegroundColor Green

Certificate Summary Table

File	Location	Purpose	Keep Secret?
`ca.key`	CA	Signs all certificates	YES (Master key)
`ca.crt`	Both	Root trust anchor	No
`server.key`	Server	Server TLS authentication	YES
`server.crt`	Server	Server identity proof	No
`tester.key`	Tester	Tester TLS authentication	YES
`tester.crt`	Tester	Tester identity proof	No

Useful Verification Commands

bash

# View certificate details
openssl x509 -in server/server.crt -text -noout

# Verify certificate chain
openssl verify -CAfile ca/ca.crt server/server.crt
openssl verify -CAfile ca/ca.crt tester/tester.crt

# Test TLS connection (server side)
openssl s_server -accept 13400 -cert server/server.crt -key server/server.key -CAfile ca/ca.crt -Verify 1

# Test TLS connection (tester side)
openssl s_client -connect localhost:13400 -cert tester/tester.crt -key tester/tester.key -CAfile ca/ca.crt

TLS Handshake Flow (DoIP v3)

    Tester (Client)                           DoIP Entity (Server)
         |                                            |
         |  1. ClientHello                            |
         |  ----------------------------------------> |
         |                                            |
         |  2. ServerHello + server.crt               |
         |  <---------------------------------------- |
         |                                            |
         |  3. Verify server.crt with ca.crt          |
         |                                            |
         |  4. CertificateRequest (mutual TLS)        |
         |  <---------------------------------------- |
         |                                            |
         |  5. tester.crt + KeyExchange               |
         |  ----------------------------------------> |
         |                                            |
         |  6. Verify tester.crt with ca.crt          |
         |                                            |
         |  7. Finished                               |
         |  <---------------------------------------> |
         |                                            |
         |  === Secure DoIP Communication ===         |
         |                                            |

Notes

Key Length: CA uses 4096 bits for stronger security, while server/tester use 2048 bits for balance between security and performance.
Validity Period: CA is valid for 10 years, while server/tester certificates are valid for 1 year. Renew before expiration.
CN (Common Name): Can be customized based on your requirements. For production, use actual domain names or VIN numbers.
DoIP Port: Default DoIP TLS port is 3496 (secure) vs 13400 (unsecure).
Production Use: For production environments, consider using a proper PKI infrastructure and HSM for key storage.

EcuBus Hardware

DoIP

Script

Database

Setup

DoIP v3 TLS Certificates Generation Guide

Overview

Directory Structure

Step-by-Step Commands

1. Create Directory Structure

2. Generate CA (Certificate Authority)

3. Generate Server Certificate (DoIP Entity / ECU / Gateway)

4. Generate Tester Certificate (Diagnostic Tester / Client)

Complete Script

PowerShell Script (Windows)

Certificate Summary Table

Useful Verification Commands

TLS Handshake Flow (DoIP v3)

Notes

DoIP

DoIP v3 TLS Certificates Generation Guide ​

Overview ​

Directory Structure ​

Step-by-Step Commands ​

1. Create Directory Structure ​

2. Generate CA (Certificate Authority) ​

3. Generate Server Certificate (DoIP Entity / ECU / Gateway) ​

4. Generate Tester Certificate (Diagnostic Tester / Client) ​

Complete Script ​

PowerShell Script (Windows) ​

Certificate Summary Table ​

Useful Verification Commands ​

TLS Handshake Flow (DoIP v3) ​

Notes ​

DoIP v3 TLS Certificates Generation Guide

Overview

Directory Structure

Step-by-Step Commands

1. Create Directory Structure

2. Generate CA (Certificate Authority)

3. Generate Server Certificate (DoIP Entity / ECU / Gateway)

4. Generate Tester Certificate (Diagnostic Tester / Client)

Complete Script

PowerShell Script (Windows)

Certificate Summary Table

Useful Verification Commands

TLS Handshake Flow (DoIP v3)

Notes