Guide

Hash-Verifiable Evidence: Making Vendor Claims Auditable

Every claim TrustVendor makes about a vendor is linked to a specific character span in a specific document snapshot, and every snapshot carries a sha256 hash. This means that for any finding — "this vendor holds SOC 2 Type II as of October 2024" — you can verify the hash of the source document yourself using standard tooling, without trusting TrustVendor's representation. The integrity guarantee is mathematical, not reputational.

Why does hash verification matter?

In traditional vendor risk, trust is reputational: you trust the vendor’s self-attestation, the auditor’s opinion, and your vendor risk tool’s data pipeline. Each link in that chain is a potential point of failure or manipulation. Hash verification breaks that chain: the sha256 of the original document is a mathematical commitment. If the hash matches, the document is exactly what was fetched at that timestamp. No intermediary in the chain can alter the document without invalidating the hash.

How does TrustVendor hash documents?

When TrustVendor’s fetcher retrieves a document — an HTML page, a PDF, a JSON API response — it computes the sha256 hash of the raw bytes before any processing. The hash and the document bytes are stored in TrustVendor’s immutable blob store. All subsequent processing — parsing, extraction, diffing — operates on the stored bytes, not on a re-fetched copy. The hash is the canonical identifier for that version of that document.

How do I verify a hash from the evidence drawer?

In TrustVendor’s evidence drawer, each artifact shows its sha256 hash. You can verify the hash by downloading the raw artifact (a button is provided) and running sha256sum <filename> (Linux/macOS) or certutil -hashfile <filename> SHA256 (Windows) and comparing the output to the displayed hash. If they match, the document you downloaded is byte-for-byte identical to what TrustVendor processed when it made the claim.

What does the “verify hash” button do in the UI?

The verify hash button in TrustVendor’s evidence drawer is not theatre — it recomputes the sha256 of the stored artifact bytes in the browser using the Web Crypto API and compares the result to the stored hash. If they match, a green indicator confirms integrity. This verification is client-side: the result does not depend on TrustVendor’s servers returning a specific answer. The browser does the math.

Common questions

What if the vendor changes their document after TrustVendor has hashed it?
That is exactly what the snapshot model is designed to detect. When TrustVendor fetches the document again and the hash differs from the previous version, it stores a new snapshot and runs the differ to produce a byte-level diff. The old snapshot and its hash remain in storage, providing a verifiable record of what the document said before the change.
Can TrustVendor verify PDFs that are encrypted or password-protected?
TrustVendor can only process documents it can access. Password-protected PDFs require the customer to upload the document directly. TrustVendor processes the provided bytes, stores the hash, and extracts claims from the content — without retaining the password or sharing the document.
Is sha256 still considered secure for this use case?
Yes. For document integrity verification — confirming that a document has not been altered since a specific timestamp — sha256 provides more than sufficient security. Pre-image resistance and collision resistance at sha256's security level are not practically breakable.

Related guides

Bitemporal Claims: How TrustVendor Models What Vendors Promised and WhenSOC 2 Reports Explained: What Compliance Teams Need to KnowEvidence Decay: Why Freshness Is a First-Class Risk Concept

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