avbtool is the reference implementation for generating, extracting, and verifying the cryptographic metadata required for AVB. It doesn't "boot" anything itself; instead, it prepares boot images, vendor partitions, and system images with hash trees, footers, and digital signatures. The bootloader then uses that metadata to detect tampering before the kernel is ever executed.
For the embedded systems engineer flashing a last ROM onto a 2018 smartphone, or the student peering into Android’s boot security with a logic analyzer, avbtool 1.1.0 remains a small, sharp tool—an elegant piece of cryptographic plumbing that refuses to be ignored. avbtool 1.1.0
The binary will be in out/host/linux-x86/bin/avbtool . Note that avbtool is a Python script (later versions are Python 3). Version 1.1.0 may still depend on Python 2.7. For the embedded systems engineer flashing a last
This creates a 4096-bit RSA private key. This file must be kept secret and secure. If this key is leaked, an attacker could sign malicious Version 1
| Option | Purpose | |--------|---------| | --algorithm | Signing algorithm (e.g., SHA256_RSA2048 , SHA512_RSA4096 ) | | --key | Path to PEM-encoded RSA private key | | --rollback_index | 64-bit value; must increase with each update | | --include_descriptors_from_image | Extracts footer from another image and includes it | | --append_vbmeta_image | Appends vbmeta metadata directly to a partition | | --prop | Sets a custom com.android.build.* property | | --padding_size | Adds padding for future updates without resizing |