| Field | Size (bytes) | Description | |-------|--------------|-------------| | magic | 4 | Constant AVB_MAGIC = "AVB0" | | version_major | 4 | AVB format major version (e.g., 1) | | version_minor | 4 | Minor version (e.g., 0) | | authentication_data_block_size | 8 | Size of signature + public key (if embedded) | | auxiliary_data_block_size | 8 | Size of descriptors, rollback index, etc. | | algorithm_type | 4 | Signing algorithm (e.g., SHA256_RSA2048) | | hash_tree_offset | 8 | Offset to hash tree (if used) | | rollback_index | 8 | Anti-rollback counter | | flags | 4 | e.g., AVB_FLAGS_VERIFICATION_DISABLED | | public_key (variable) | – | Embedded public key (optional) | | signature (variable) | – | Signature of the header + auxiliary data |
Are you planning to or just exploring the Android boot architecture ? DroidGuard: A Deep Dive into SafetyNet - Sstic vbmeta
VBmeta is a dedicated partition (and corresponding image file, vbmeta.img ) introduced with Android 8.0 (Oreo) and the AVB 2.0 standard. Its primary role is to store and integrity metadata for other system partitions like boot , system , and vendor .
In the modern Android ecosystem, security is paramount. While users often interact with the graphical interface or the kernel, one of the most critical components operating behind the scenes is the partition. Short for Verified Boot Metadata , this component acts as the master key and rulebook for the Android Verified Boot (AVB) process. | Field | Size (bytes) | Description |
Some common metadata entries found in a VBMeta structure include:
avbtool info_image --image vbmeta.img
When flashing a device using fastboot , developers use specific flags to bypass these checks: fastboot flash vbmeta vbmeta.img
