Co-Spend Heuristic
Definition
The inference that when multiple Bitcoin inputs appear in one transaction, all those input addresses are controlled by the same entity, because constructing the transaction requires signing with every input's private key.
- Domain
- Bitcoin blockchain analysis
- Also called
- Common-input-ownership heuristic
- Basis
- All inputs to one transaction must be signed by their owner
- Output
- Address clustering into likely single-entity wallets
Common questions
Is the co-spend heuristic always reliable?+
No. CoinJoin and similar coordinated-mixing transactions deliberately combine inputs from unrelated parties to defeat this exact inference, so clusters built purely on co-spend can wrongly merge separate owners when mixing services are involved.
How is the co-spend heuristic used in an investigation?+
Investigators run it across a blockchain's full transaction history to group addresses into wallet clusters, then combine those clusters with off-chain data such as exchange KYC records or IP logs to attribute a cluster to a real identity.
Related terms
- Attribution Database
- A commercial or law-enforcement dataset that maps known addresses or address clusters to real-world entities: exchanges, darknet markets, ransomware operators, sanctioned individuals,...
- Change-Address Heuristic
- The inference that one output from a Bitcoin transaction (usually the smaller one, to a fresh address) is change returning to the...
- De-Anonymisation
- The process of linking a pseudonymous address or cluster to a real-world identity. Most commonly achieved through exchange KYC records, but also...
- Mixing (Tumbling)
- A service or protocol that accepts cryptocurrency inputs from multiple users and returns equivalent outputs in a way designed to break the...
- Peel Chain
- A transaction pattern where one large input is repeatedly split, sending most of the value one hop forward and a small remainder...