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These are the steps that need to be completed for the certificate hierarchy:

• Generate Root CA

• Generate Device certificate signed with the Root CA’s private key

Anchor
RootCA RootCA

Generate Root Certificate

1. Generate a private key file (ca.key) for the Root CA using the command below. You may choose to enter a passphrase to be associated with the ca.key file as well.

   Tip
   Make note of this passphrase if you set one for the Root CA private key file (ca.key) as it will be used multiple times.

   
   

   Code Block
   openssl genrsa -des3 -out ca/ca.key 4096

   
   

2. Generate a self-signed certificate (ca.crt) for the Root CA using the command below. This command generates a new self-signed X.509 certificate named "ca.crt" valid for 3650 days (10 years) using the RSA private key "ca.key". You will be required to enter the pass phrase associated with the private key file "ca.key". 

   Code Block
   openssl req -new -x509 -key ca/ca.key -days 3650 -out ca/ca.crt

   
   

   Note
   There are a number of fields associated with the creation of the certificate. Fill them out with your relevant details.

   
   

   Code Block
   title Example CA Creation
   $ openssl req -new -x509 -key ca/ca.key -days 3650 -out ca/ca.crt Enter pass phrase for ca/ca.key: You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:US State or Province Name (full name) [Some-State]:KS Locality Name (eg, city) []:Stilwell Organization Name (eg, company) [Internet Widgits Pty Ltd]:Cirrus Link Solutions Organizational Unit Name (eg, section) []:Support Common Name (e.g. server FQDN or YOUR name) []:CLS Example Root CA   Email Address []: $

   
   

3. Azure will need the certificates in PEM format. Convert the CRT format to PEM format using the command below.

   Code Block
   openssl x509 -in ca/ca.crt -out ca/ca.pem -outform PEM

   
   

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Anchor
DeviceCert DeviceCert

Generate Device Certificate

1. Generate private key in PSCK8 format (CertDevice.key) for the device using the command below.

   Code Block
   openssl genrsa -out certs/device/CertDevice.key 4096

   
   

2. Generate a Certificate Signing Request (CSR) for the device using the command below. This command generates a new CSR named "CertDevice.csr’ using the RSA private key "CertDevice.key".

   Code Block
   openssl req -new -key certs/device/CertDevice.key -out certs/device/CertDevice.csr

   
   

   Note
   There are a number of fields associated with the creation of the certificate. Fill them out with your relevant details.

   
   

   Code Block
   title Example Device CSR Creation
   $ openssl req -new -key certs/device/CertDevice.key -out certs/device/CertDevice.csr You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:US State or Province Name (full name) [Some-State]:KS Locality Name (eg, city) []:Stilwell Organization Name (eg, company) [Internet Widgits Pty Ltd]:Cirrus Link Solutions Organizational Unit Name (eg, section) []:Support Common Name (e.g. server FQDN or YOUR name) []:Device01 Email Address []:   Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []: An optional company name []: $

   
   

   Warning
   The Common Name or FQDN must match the name of the logical Device Id in IoT Hub. In our example the Device Id is Device01

   
   

3. Sign the Device CSR with the Device CA using the command below. This command will sign the CSR "CertDevice.csr" with the Root CA certificate ‘ca.crt’ and Root CA's RSA private key ‘ca.key’, creating a new X.509 certificate named ‘CertDevice.crt’ valid for 365 days (1 year). You will be required to enter the passphrase associated with the private key file "ca.key".

   Code Block
   openssl x509 -req -in certs/device/CertDevice.csr -CA ca/ca.crt -CAkey ca/ca.key -CAcreateserial -out certs/device/CertDevice.crt -days 365

   
   

4. Azure will need the certificate in PEM format. Convert the CRT format to PEM format using the command below:

   Code Block
   openssl x509 -in certs/device/CertDevice.crt -out certs/device/CertDevice.pem -outform PEM

   
   

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iotcerts/
├── ca/
│   ├── ca.crt
│   ├── ca.pem
│   ├── ca.key
└── certs/
    ├── device/
       ├── CertDevice.crt
       ├── CertDevice.pem
       ├── CertDevice.csr
       └── CertDevice.key

Add Root Certificate to IoT Hub

• On the IoT Hub resource Overview page, click “Certificates” menu on the left blade, and click the “Add” button.
• Give a certificate name (eg. MyOrg RootCertificate) and import the ca.pem file from your iotcerts/ca folder. Check the “Set certificate status to verified on upload” checkbox and click Save.
  

Add device certificates to Azure Injector IoT Hub configuration

Navigate to the Azure Injector > Settings > Azure IoT Hubs > Certificates and add the certificates as shown below:

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