// a) Sanitize input string cleaned = SanitizeKey(userInput); if (cleaned == null) return RegistrationResult.InvalidFormat;
// c) Cryptographic verification if (!VerifySignature(cleaned)) return RegistrationResult.InvalidSignature;
// f) Persist securely SaveLicenseSecurely(payload); finecam registration code
// 1. Public API -------------------------------------------------------------- public RegistrationResult Register(string userInput)
// e) Check expiration / feature flags if (payload.IsExpired) return RegistrationResult.Expired; if (!IsFeatureAllowed(payload)) return RegistrationResult.NotAuthorized; if (cleaned == null) return RegistrationResult.InvalidFormat
// Typically: key = <payload>.<signature> // Decrypt payload (AES‑GCM) using a per‑install random key that is wrapped // with the public key. Return a typed object.
// Trim, upper‑case, remove whitespace/hyphens as needed // Return null if characters outside allowed set are found // f) Persist securely SaveLicenseSecurely(payload)
// 1) Decode base64 segment that contains the digital signature // 2) Use the embedded public key (RSA 2048 or ECDSA P‑256) to verify // 3) Constant‑time comparison to avoid timing attacks