according to Tor's specifications, the fingerprint is
A fingerprint (a HASH_LEN-byte of asn1 encoded public key, encoded in hex, with a single space after every 4 characters) for this router's identity key. A descriptor is considered invalid (and MUST be rejected) if the fingerprint line does not match the public key.
But I can't manage to recalculate it.
If I correctly understand, the fingerprint is 20 bytes of HEX value of the 'authority_signing_key', right ?