Originally published at htpbe.tech . The version on htpbe.tech stays in sync with the latest detection algorithm — refer to it for the canonical text. When checking PDF authenticity, two methods dominate the conversation: digital signatures and metadata analysis. Both provide evidence about a document’s history and integrity, but they work differently and offer different levels of proof. The question is: which actually proves authenticity? The answer is more nuanced than you might expect. Digital signatures provide cryptographic proof of integrity, while metadata reveals creation and modification history. Understanding both — and their limitations — is essential for effective PDF tamper detection. This article explores digital signatures and metadata in depth, comparing their strengths, weaknesses, and appropriate use cases. Whether you are checking contracts, invoices, certificates, or legal documents, knowing which method to trust matters.…