Someone opens a real payslip in a free PDF editor, changes one number, and saves. Nothing looks wrong, because nothing is wrong with how it looks.
Aletheia reads the parts of a document that a forger does not think to fix. Classical checking asks whether a document looks right. Aletheia asks whether it makes sense: whether the arithmetic holds, whether the claimed salary matches money that actually arrived, whether the pay date matches the employer's cycle.
Three layers of detection, working independently and correlated: file and pixel forensics, content logic and plausibility, and behavioural consistency against real account data.
The reason all three matter: a manipulated document is real and then edited, and forensics catches it. An original fake was never real, was generated cleanly in one pass, and leaves forensics nothing to find. A tool with one layer catches one of these and calls the other clean.
One of the five capabilities that compose: trust the documents, on its own or combined with the rest of the platform, in whatever order a case calls for.
Runs inside the platform. Works without it.