Document magic depends on believable authenticity: “is this really from who it claims to be from.” Historically, seals were a major technology of authenticity for charters and official documents, functioning as a visible, hard-to-forge token of authority - nationalarchives.gov.uk 
This is the same design problem reappearing in modern form: make authority portable, verifiable, and difficult to counterfeit.
# Cryptographic Document Magic
Digital systems recreate seals using cryptography: signatures allow a verifier to check that a document was issued by a particular key, and that it has not been altered.
Public Key Infrastructure (PKI) is one widely used way of managing this at scale, especially in e-signatures and secure transactions.
A more “web-native” approach is the W3C Verifiable Credentials model: issuers make signed claims about a subject, holders carry them, and verifiers check them, aiming for portability and machine verification while supporting privacy-preserving designs.
Decentralized Identifiers (DIDs) are another building block: identifiers designed to be decoupled from centralized registries, so a subject can prove control of an identifier without relying on a single identity provider.