Manufacturers use a private key to sign the build and include a corresponding public key in the device's recovery partition.
Developers often use the SignApk.jar tool to sign their own custom packages.
An is a compressed archive containing the files necessary to update an Android system, along with a cryptographic signature that verifies the file's integrity and origin. update-signed.zip
The term "signed" indicates that the package has been processed with a private key—usually by the Original Equipment Manufacturer (OEM) like Samsung or Google. This allows the device's Stock Recovery to confirm that the update is official and hasn't been tampered with by a third party. How the Signing Process Works
Many modern Android versions allow you to install a ZIP directly from the menu: Sign builds for release - Android Open Source Project Manufacturers use a private key to sign the
For an update to be accepted by a stock recovery, it must pass a "whole-file signature verification".
When you attempt to flash the file, the recovery checks the last few bytes of the ZIP (the footer) for specific markers (like 0xff ) and then validates the cryptographic hash against its internal store. How to Use update-signed.zip There are two primary ways to apply these updates manually: 1. Via Local Update (System Settings) The term "signed" indicates that the package has
Understanding update-signed.zip: A Guide to Android OTA Packages