mitchellpkt.github.io

Boolean heuristic	Yes	No
tx_extra includes encrypted PID	A	B
tx_extra includes unencrypted PID	C	D
tx_extra includes unknown field	E	F
unlock_time > 0	G	H
decoy selection matches core algo	I	J
fee selection matches core algo	K	L
current bulletproofs format	M	N
…	…	…

Notes:

• These transaction characteristics are visible on-chain, so anybody with a copy of the ledger can note the fingerprint string for every transaction.
• At the current network version, all transactions generated by the core wallet should have fingerprint F0 = ADFHIKM.
• An F0 fingerprint does not necessarily indicate use of core software (since other wallets should mimic F0). However the appearance of a non-F0 signature does indicate the use of non-core software.
• Within a given era, length(unique({fingerprints})) provides a lower bound on the number of different types of software in use.
• F0 changes during some network upgrades, and is thus a function of version/time/block height.
• It may be helpful to consider the difference fingerprint (D) which returns only characteristics where the transaction deviates from the core software during that era, or returns 0 if the signature matches the core software. So in the current era (F0 = ADFHIKM) a transaction that is constructed normally except for a non-zero lock time would have a difference fingerprint D = 000G00 = G
• Numeric values may be added after relevant Y/N, for example ADFG3IKM indicating that the unlock time was 8 blocks. In 2020 common unlock times include 0 (core software), 1, 3, 4, and 12. Depending on the nature of your analysis it may make sense to keep the ADFG3IK transactions separate from the ADFG12IKM transactions.
• Any subset of these could be used. You can opt-out from including fees and decoys if probabilistic heuristics are not your cup of tea.
• See my Konferenco talk (Visualizing Monero: A Figure is Worth a Thousand Logs) for more details on software fingerprinting, anonymity puddles, and linking transactions by their fees and decoy selection algorithm.