Technical Paper by Malcolm Weir
Video Attestation for Evidentiary Purposes
Digital video is easier to capture, move, and analyze than ever before, but it is also easier to manipulate. As video becomes part of legal, operational, military, and mission-review workflows, teams need a way to know whether the video being reviewed is the video that was actually recorded.
In this white paper, Malcolm Weir explores cryptographic approaches for providing assurance that recorded video, and other forms of sequential data, have not been manipulated or otherwise tampered with. The discussion is especially relevant as AI tools make forgery more sophisticated while autonomous systems reduce the amount of continuous human monitoring behind the camera.
Why Video Attestation Matters
The question is no longer simply whether a camera captured something. The evidentiary question is how much confidence to place in a particular photo or video after it has been recorded, stored, transferred, or reviewed.
For fixed cameras, analysts may have hours of reference material to compare against. For mobile cameras, aircraft, maritime platforms, unmanned systems, and autonomous vehicles, the scene is constantly changing. That makes it much harder to use visual comparison alone to detect whether footage has been altered.
Video attestation helps address that challenge by using cryptographic methods to detect manipulation and strengthen confidence in the integrity and origin of recorded video.
What the Paper Covers
Storage Encryption
The paper explains why storage encryption can help protect confidentiality, but may not be enough to prove authenticity. Anyone with the encryption key may still have access to modify the data, and whole-volume encryption does not provide file-level granularity.
File and Stream Encryption
File-based or stream-based encryption can add granularity, but it also creates additional key-handling complexity. Each video stream or file may require its own key, and metadata can still reveal sensitive information even when the video itself is encrypted.
Hash Operations
Cryptographic hash functions can detect changes to digital data without requiring the video to remain locked away. A small change in the source data produces a significantly different output, making hashes useful for identifying tampering.
Signed Hashes
The paper discusses using public key cryptography to sign hash values. This adds both integrity and authentication by helping show that the video has not been modified and that it came from the specified source, assuming proper protection of the private key.
Post-Quantum Considerations
The paper also addresses future cryptographic requirements, including the transition away from older asymmetric algorithms and the relevance of newer post-quantum approaches.
Embedding Integrity Data in the Video Stream
Rather than storing attestation data separately, the paper explores embedding signed hash information directly into the MPEG-2 Transport Stream. It discusses where that integrity data might live, how often it should be inserted, and whether it should include video, audio, KLV metadata, or other stream components.
Overlapping Signed Hashes
One proposed approach uses overlapping signed hashes to create alternating integrity blocks. This helps ensure that data cannot be inserted between protected chunks and makes the integrity protection easier to demonstrate.
Beyond Video
Although the paper discusses video applications, the same techniques can apply to other packetized data, including serial streaming telemetry. By adding cryptographically signed hashes, systems can help assure both the integrity of the signal and its origin.
About Ampex Data Systems
Ampex Data Systems designs rugged mission data systems for aerospace, defense, and other demanding environments. Our recording, storage, security, and compute solutions help programs capture, protect, and preserve mission-critical data from the edge through post-mission review.