Hello Thorsten,

Thank you for your response, this confirms what we have also found in our 
research in the meantime. 
We will find a better security key/certs management in the coming future to 
overcome this kind of problem.

Best regards,

Ingénieur Système Embarqué STIMIO
1 Avenue du Professeur Jean Rouxel, ZAC de la Fleuriaye, 44470 Carquefou

-----Message d'origine-----
De : Thorsten Scherer <tk-sche...@mailbox.org> 
Envoyé : mardi 3 septembre 2019 23:44
À : Adrien Martin <adrien.mar...@stimio.fr>
Cc : rauc@pengutronix.de; meta-r...@pengutronix.de; Patrick Boettcher 
Objet : Re: [RAUC] [Yocto] Rauc certificate expiration management advices

Hello Adrien,

On Wed, Aug 14, 2019 at 03:56:07PM +0000, Adrien Martin wrote:
> 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 ?

I guess you're trying to replace the expired certificate in a "Single Key" 
scenario, which is not possible [1].  The documentaion lists some other 
variants, though I am not sure which one applies best to your use-case (maybe 
install hooks??).

> Thank you very much.
> Best regards,
> Adrien MARTIN
> Ingénieur Système Embarqué STIMIO
> adrien.mar...@stimio.fr<mailto:adrien.mar...@stimio.fr>
> 1 Avenue du Professeur Jean Rouxel, ZAC de la Fleuriaye, 44470 
> Carquefou www.stimio.fr<http://www.stimio.fr/>
> [stimio_logo]
> _______________________________________________
> RAUC mailing list

Best regards,

[1] https://rauc.readthedocs.io/en/latest/advanced.html#single-key

Thorsten Scherer <tk-sche...@mailbox.org>

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