Heuristics overview

SiriScore runs 12 privacy checks. Penalty heuristics deduct from the score; positive heuristics add to it or suppress false positives.

Penalty heuristics

ID	Name	Severity	Weight	Requires network
H1	Script type mismatch	Critical	25	No
H2	Round payment amount	Warning	15	No
H3	Address reuse on input	Critical	20	Yes
H4	UTXO age clustering	Warning	10	Yes
H5	High input count (CIOH)	Warning	10	No
H6	Dust input present	Warning	10	No
H7	Non-BIP69 ordering	Info	5	No
H8	Tainted labelled UTXO	Critical	25 + score cap at 40	No
H13	nLockTime anti-fee-sniping	Info	5	No

Positive heuristics

ID	Name	Severity	Effect	What triggers it
H9	Input is a coinjoin output	Info	Suppresses H5	Whirlpool denomination or coinjoin label
H10	Transaction is a coinjoin	Info	+10 score bonus, suppresses H5	Whirlpool / Wasabi / JoinMarket structure
H11	Payjoin opportunity	Info / Warning	No penalty	BIP-21 URI with pj= parameter

Silent payments (BIP-352)

Silent payments awareness is built into H3. When H3 detects address reuse, it checks whether the recipient already supports BIP-352 silent payments and adjusts its suggestion accordingly.

Scoring formula

score = min(100, max(0, 100 − sum(penalty weights) + sum(bonus weights)))

• Weights are additive — multiple heuristics can fire on the same transaction
• H10 uses weight = −10 (negative penalty = bonus)
• H8 additionally caps the score at 40 regardless of other heuristics
• H9 or H10 firing strips H5 from the findings (coinjoin breaks the CIOH assumption)