Accountability investigations often rely on digitized primary sources – such as the UN payroll records unearthed in our Bosnia war crimes probe – that contain sensitive PII of individuals not central to the investigation. While redacting this information is a journalistic and ethical necessity, it creates a “trust gap”. In an era of widespread denialism and “cheapfakes,” any manual modification to a source document can be weaponized by bad actors to claim the entire record is a forgery, undermining the evidentiary weight of critical testimonies.

In partnership with our principal investigator’s Professor Dan Boneh’s students from the Stanford Applied Cryptography Group, Starling developed a workflow that integrates forensic ingestion with cryptographic proof systems, and managed redactions.

It relies on a Zero-Knowledge Proof that certifies the relationship between the original and the redacted file. This technology generates a mathematical proof that the only changes made to the published PDF were the addition of black boxes over specific pixels. This allows third parties, such as expert witnesses, to “check the math” and verify that no text was altered or deleted, maintaining the document’s integrity while fulfilling privacy obligations