Video Evidence Has Two Authentication Problems. Most Teams Are Solving One.

A dashcam file gets uploaded to a carrier portal. High-resolution. Clear chain-of-custody paperwork. Attached to a disputed claim over pre-existing vehicle damage.

The defense asks one question: when was this recorded?

Not whether it was altered. Not whether the vehicle matches. When.

That's a different question than most evidence teams prepare for. And it's the one that tends to derail otherwise solid documentation.

Integrity vs. Timing: Two Separate Arguments

Authentication of digital evidence comes down to two distinct claims.

The first is integrity: has this file been modified since it was created? Hash verification handles this. SHA-256 is the standard. If the hash of the current file matches the hash on record, the file hasn't changed.

The second is timing: when did this evidence first exist? That's not a hash problem. A hash tells you what the file is. It doesn't tell you when the file was created relative to a loss event.

Claims operations often conflate these. They verify the file, confirm it hasn't been altered, and treat that as authentication. A prepared opposing counsel will ask for more. The question isn't whether the hash matched. The question is when the file was created.

What EXIF and Metadata Actually Prove

Video files carry metadata. Smartphones embed timestamps, GPS coordinates, device identifiers. Dashcams log time and location. This looks like proof of timing.

It's not.

EXIF data lives inside the file. It can be modified by software, stripped during transfer, or corrupted during platform uploads. A timestamp of "March 15, 2:30 PM" proves nothing about when the video was actually recorded. Anyone with basic file editing tools can change that timestamp.

Courts know this. FRE 901(b)(9) requires showing that a "process or system" produces "an accurate result." Pointing to an editable timestamp doesn't meet that standard.

The C2PA Layer

C2PA (Content Credentials) addresses some of these problems. It's the industry standard for provenance metadata, backed by Adobe, Google, Meta, Microsoft, and OpenAI. Newer devices sign media files cryptographically at capture time.

Samsung Galaxy S25 and Google Pixel 10 embed C2PA signatures directly from the camera. The signature includes device identity, capture time, and a chain of any edits applied. This is stronger than EXIF data because it's cryptographically verified.

But C2PA has a weakness: the credential lives inside the file. Platform re-uploads can strip it. File format conversions can corrupt it. Email attachments can lose it. In a legal context, this creates a chain-of-custody gap.

The Blockchain Solution

A blockchain anchor exists independently of the file. The file can be transferred, converted, or uploaded anywhere. The anchor remains on an immutable public ledger.

Here's how it works: generate a SHA-256 hash of the video file, anchor that hash to Bitcoin and Polygon blockchains with a timestamp. The blockchain record proves the file existed at a specific point in time, regardless of what happens to the file afterward.

No platform can strip a blockchain anchor. No transfer can corrupt it. No editing software can modify it. The proof exists permanently on a public ledger that anyone can verify.

Dual-Layer Documentation

The strongest evidence documentation uses both layers:

C2PA for provenance: who captured it, when, with what device, what edits were applied.

Blockchain anchoring for temporal proof: immutable evidence that the file existed before the loss date.

An adjuster documenting a property inspection can capture video with C2PA credentials, then anchor the hash to blockchain immediately. If the claim gets disputed six months later, both layers survive. The C2PA shows the capture metadata. The blockchain proves it existed before any loss event.

Implementation Reality

Most evidence teams aren't thinking about blockchain anchoring yet. They're focused on traditional chain-of-custody protocols and file integrity checks. But opposing counsel is getting smarter about temporal authentication challenges.

Ask your vendor: can you prove when this evidence was created, not just that it hasn't been altered?

The answer determines how well your documentation will hold up under scrutiny.