looksLikeSignature static method
A minimal signature format sanity check. This does NOT perform real
cryptographic verification — see CryptoUtils.verifySignature for
that. This just guards against obviously malformed values (empty,
too short, whitespace-only).
Implementation
static bool looksLikeSignature(String? signature) {
if (signature == null) return false;
final trimmed = signature.trim();
if (trimmed.isEmpty) return false;
if (trimmed.length < 8) return false;
return true;
}