AFF4

AFF4, standing for Advanced Forensic File Format, is an open, extensible container format designed for the storage and management of digital forensic data. It provides a self-describing format capable of storing disk images, file system metadata, and analysis results within a single, coherent container. AFF4 emphasizes scalability to large data sets, data integrity, and provenance, aiming to support both investigative workflows and research.

The architecture of AFF4 is object-based. A container is composed of various AFF4 objects such as images, volumes, directories, files, and streams, each with metadata describing its content and provenance. The data streams allow efficient access to large images without requiring full extraction, while the metadata layer records creation times, authorship, checksums, and version history. AFF4 supports versioning, snapshots, and nested containers, enabling researchers to generate and preserve multiple analyses over the same evidence.

Key features include support for large files and volumes, streaming access, random I/O, cross-platform portability, and extensibility through a pluggable set of data stores and compression algorithms. Integrity is addressed through checksums and optional cryptographic signing, helping maintain chain-of-custody and verifiability. Being open and community-driven, AFF4 has implementations in multiple languages and is used in academic research, digital forensics tooling, and proof-of-concept workflows.

Because of its design goals, AFF4 is often considered for complex investigations where multiple data sources and analyses must be stored in a unified, auditable container. Its adoption varies, with use concentrated in research projects and some open-source tools rather than as a universal standard.