Cleaning a signed PDF
Not a concealment technique — a disclosure that the source PDF was digitally signed and the cleaned artifact returned is no longer the signed bytes.
How the text is hidden
The PDF cleaner appends an incremental update rather than rewriting the file, so the signed revision survives intact as the earlier revision of the returned document and nothing is corrupted. What changes is what the signature covers: the bytes handed back are not the bytes that were signed.
Why a model still reads it
This entry describes the cleaned artifact, not concealed text. It exists so that a caller who cleans a signed contract is told what happened to the signature rather than discovering it downstream.
What we do about it
Emitted in analyzeCore when cleanPdf reports signatureInvalidated and the artifact was actually rewritten. It is a disclosure family finding at informational with action disclosed and chars: 0 — a property of the file, not a quantity of text — so it cannot move the verdict. The engine deliberately does not decline to clean signed PDFs; the same notice is also written into the cleaned file's metadata so it outlives the response.
How often it fires
Not measured. We publish a rate only where one has been measured against a named corpus of the right format, and no figure exists for this technique yet. Absence means unknown — never low.
Check your own file
Three commands: a key, credit, a verdict.
Start with the API