The process begins with provisioning a device with the public verification key, and configuring the Mender Client to use the key with the ArtifactVerifyKey configuration option. After an image is built, it gets signed by the Signing system. Although it is convenient and possible to use the Build system as the Signing system, this lowers the security as unauthorized access to the private signing key is made easier for potential attackers e.
The best practice is to only sign Artifacts on some offline system, ideally as a manual operation after careful inspection of the Artifact. After the Artifact is created and signed it can be uploaded to the Mender Server, where the Mender Client will download it from. During the update installation process, the Mender Client will verify the Artifact using the corresponding public key that it was provisioned with.
The Artifact will only be installed if the verification is successful. If Artifacts are not signed or the verification fails, the update process will be aborted and the Mender Client will report an error to the Mender Server. If the Mender Client is configured to enable signature verification through the ArtifactVerifyKey option , it will reject any unsigned Artifacts.
This is necessary because otherwise an attacker could simply inject unsigned Artifacts to bypass the signature verification. In order to sign and later on verify the signature of the Mender Artifact we need to generate a private and public key pair. Please follow the respective section below, depending on the signature algorithm you want to use.
After generating the keys you will have a file private. The file public.
The resulting private. We use the mender-artifact tool to create a signed Artifact. If the signatures match, the request is processed.
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Every application that is run on the Android platform must be signed by the developer. Applications that attempt to install without being signed will be rejected by either Google Play or the package installer on the Android device. On Google Play, application signing bridges the trust Google has with the developer and the trust the developer has with their application.
Developers know their application is provided, unmodified, to the Android device; and developers can be held accountable for behavior of their application.
On Android, application signing is the first step to placing an application in its Application Sandbox. The signed application certificate defines which user ID is associated with which application; different applications run under different user IDs. Application signing ensures that one application cannot access any other application except through well-defined IPC.
If the certificate or, more accurately, the public key in the certificate matches the key used to sign any other APK on the device, the new APK has the option to specify in the manifest that it will share a UID with the other similarly-signed APKs. Applications can be signed by a third-party OEM, operator, alternative market or self-signed. Android provides code signing using self-signed certificates that developers can generate without external assistance or permission. Applications do not have to be signed by a central authority.