Hello,
My name is Adrien Martin, embedded system engineer at STIMIO and I am facing an issue with rauc update security.
Just to let you know, I don’t have much experience with security concepts in general.
I am using Rauc (v0.4, quite old I admit) for an embedded linux system (imx6ul) with barebox bootloader, all images / bundles are generated via Yocto (Poky)
Following the documentation, you need to set :
- RAUC_KEY_FILE = "path/to/key.pem" # What I call the private key
- RAUC_CERT_FILE = "path/to/cert.pem" # What I call the certificate (public key)
As a result, when generating your image and bundle, you get :
- A linux image with /etc/rauc/cert.pem integrated to your rootfs
- A signed bundle with the key.pem
My problem is what happens when the certificate is expired ?
My initial though was, I just have to generate a new cert.pem, based on the same private key.pem with a new valid lifetime period and set up this new cert in the yocto recipe.
Then, I generate the bundle via Yocto and try to install it.
This doesn’t work and gives me :
# rauc info /var/volatile/original/msdi-bundle-msdi-imx6-1.raucb
rauc-Message: Reading bundle: /var/volatile/original/msdi-bundle-msdi-imx6-1.raucb
rauc-Message: Verifying bundle...
signature verification failed: Verify error:self signed certificate
It looks like a bundle can only be use with the cert file set in the yocto recipe. This bundle will keep this cert file in /etc/rauc/ folder so all
future bundle installations will need the exact same certificate.
Could you explain me what am I missing ? What method do you recommand to manage certificates expirations over time ?
Thank you very much.
Best regards,
Adrien MARTIN
Ingénieur Système Embarqué STIMIO
1 Avenue du Professeur Jean Rouxel, ZAC de la Fleuriaye, 44470 Carquefou
