Overview

An Ed25519 signature is a 64-byte digital signature made with Truestamp’s Ed25519 signing key over a 32-byte domain-separated SHA-256 hash, never over raw user data. Truestamp signs item hashes, block hashes, entropy observation hashes, and the fixed-width signing payload of every proof bundle. A valid signature, checked against Truestamp’s public key, proves that key endorsed exactly that fingerprint and that the object has not been altered since; it does not by itself prove when the data was submitted. Ed25519 is deterministic (the same key and message always produce the same signature), fast to make and check, and small enough to embed in every record and bundle. See Ed25519 signatures for the full treatment and the proof bundle wire format for the signed payload layout.