ed25519

Public-key signatures (RFC 8032 Ed25519), implemented from scratch with no external crypto dependency. A secret seed signs; the derived public key verifies; a verifier holding only the public key cannot forge. Keys and signatures are lowercase hex; the message is raw bytes.

import io
import ed25519

let secret = ed25519.generate()           # fresh 32-byte seed (hex)
let pub = ed25519.public_key(secret)       # derive the public key (hex)
let sig = ed25519.sign(secret, "release v1")
io.print(ed25519.verify(pub, "release v1", sig))   # True
io.print(ed25519.verify(pub, "tampered", sig))     # False

Functions

• generate() — a fresh 32-byte secret seed (64 hex chars) from the OS CSPRNG. Keep it secret; anyone with it can sign as you.

• public_key(secret_hex) — derive the 32-byte public key (hex) from a secret seed.

• sign(secret_hex, message) — a 64-byte signature (hex) over message (raw bytes). Deterministic: the same seed and message always produce the same signature.

• verify(public_hex, message, signature_hex) — true iff the signature is valid. Touches only public data, rejects non-canonical signatures (S ≥ L), and returns false (never raises) on malformed input.

The implementation is validated byte-for-byte against the RFC 8032 known-answer vectors and against OpenSSL. SHA-512 comes from the hashlib module (linked automatically). This is the same code the cheatah runtime links to verify a compiled module before loading it — see SECURITY.

Per-function docs (parameters, complexity, heap behavior) are in ed25519.hpp. Tested in ../tests/ed25519_test.cpp; ASan + Valgrind clean via the QA gate.