Manage keys for software metadata
OTA Connect has a security concept that includes signing metadata files with secure, offline keys. For more information about these files, see the Uptane metadata overview.
When you initially create an account on the HERE OTA Connect Portal, all of your Uptane keys and metadata files are managed by OTA Connect. The keys are generated by our crypto service when the account is created and stored in a Vault instance. When you build software images and upload them to your account on the OTA Connect Portal, we generate the metadata and sign it for you.
However, if you choose, you can rotate that software signing key and take it offline, replacing it with a key held only by you. Because only you have the key in this scenario, the OTA Connect server can no longer sign software for you. Instead of being signed on the server, these metadata files will now be signed locally or on your build machine. The signing happens automatically whenever you push a new disk image to OTA Connect during the build process. (If you are using non-OSTree software images, you’ll have to use garage-sign to manage your metadata.)
Taking this step is recommended for all production deployments, because a person who gained access to your OTA Connect account would be able to send arbitrary malicious software to your vehicles; that single set of credentials would be a single point of failure. Once you have rotated your keys offline, the maximal impact of an account compromise would be to send an already-signed image—i.e., one that used to be valid.
Before using OTA Connect in production, however, you should create offline keys that you manage yourself, then rotate out the default keys that were automatically created for your account on the OTA Connect server. If you don’t do this, you expose yourself to risks that we describe the in the key management topic.
Instead of being signed on the server, these metadata files will now be signed locally or on your build machine. The signing happens automatically whenever you push a new disk image to OTA Connect. However, you need to update your build cofiguration first. The following procedures show you how to do this.
Before you start, make sure that you’ve installed the garage-sign tool.
An image repository is just a directory structure containing signed metadata in JSON format. Create a new one called myimagerepo with
garage-sign init --repo myimagerepo --credentials /path/to/credentials.zip
This command creates a
./tuf/myimagerepo/ directory tree in the current directory.
This directory should be secured on an encrypted filesystem.
There are two metadata files in the repo and each file needs a new key to sign it.
garage-sign key generate --repo myimagerepo --name myroot --type rsa garage-sign key generate --repo myimagerepo --name mytargets --type rsa
This is a four-step process:
Pull the current
targets.jsonfrom OTA Connect:
garage-sign targets pull --repo myimagerepo
Perform a complete root key rotation:
garage-sign move-offline --repo myimagerepo --old-root-alias origroot \ --new-root myroot --new-targets mytargets
removes the original
rootkey from OTA Connect,
generates a new
root.jsonwith the keys generated in the previous step (
signs the new
root.jsonwith both the old and new
uploads the newly signed
root.jsonto OTA Connect
Sign the current
targets.jsonwith the new
garage-sign targets sign --repo myimagerepo --key-name mytargets
This metadata eventually expires after a predefined period. If you’d like to define your own metadata expiry period, you can add the
--expire-afteroption. For more information about these options, see our guide to managing metadata expiry dates.
Upload the newly signed
targets.jsonto OTA Connect:
garage-sign targets push --repo myimagerepo
You have now successfully taken the keys for software metadata offline.
After rotating keys, you will no longer be able to upload packages through the OTA Connect web UI—only the usual way, through bitbake.
Export the new offline
targets into a new credentials file that you can use with
garage-sign export-credentials --repo myimagerepo --target-key-name mytargets --to offline-credentials.zip
local.conf to use the new
offline-credentials.zip file and run
bitbake as before.
As part of the
bitbake process, the image’s metadata inside
targets.json is signed with your offline TUF keys. The signed
targets.json is then uploaded to your OTA Connect account.