What is Content Verification?
Two Layers of Verification
ProofCrest uses a two-layer verification system to provide the most accurate results:
The entire file is hashed byte-by-byte. An exact match means the document is identical to the original — not a single byte has changed.
Only the text content of the PDF is hashed. A content match means the readable text is unchanged, but file metadata may differ.
Why Would Only Content Match?
PDF files contain more than just visible text. They also store metadata like:
- Creation and modification timestamps
- Software used to create the PDF (Producer field)
- Author name and other document properties
- Compression settings and internal structure
- Font embedding variations
When a PDF is re-saved, printed to PDF, or opened and exported by different software, this metadata can change even though the visible content remains identical. This is a common and usually harmless occurrence.
How It Works
Registration
When an issuer registers a document, we compute both the full file hash (strict) and the text-content-only hash.
Verification
We first check the strict hash. If no match, we check the content hash as a fallback.
Result
A content match shows an amber “Content Verified” badge instead of the green “Verified” badge, so you know the text content is authentic but the file isn't byte-identical.
Content verification provides strong assurance that the readable text in the document has not been tampered with. However, for maximum confidence, the issuer should provide the exact original file that produces a strict (green) match. If in doubt, contact the issuing organization directly.