The protocol changes only the first stage of P2P relay: during an approximately ten-minute epoch it forwards a transaction through a pseudorandomly built stem graph, then the network announces it normally after the switch to fluff; it hides neither on-chain data nor changes consensus.
Dandelion++ targets one specific network trace: inferring the originating node's IP from where a new transaction first spreads. It does not encrypt the transaction, hide amounts or addresses, or erase traces that remain on the public blockchain. [1]
Relay has two phases. During stem, a transaction is not sent to every peer but travels along a narrow pseudorandom path; once a node switches to fluff, ordinary diffusion begins. This creates delay and uncertainty between the true source and the place where the transaction first spreads widely. [1]
For each approximately 10-minute epoch, Dandelion++ uses selected outbound peers to form an approximately 4-regular anonymity graph. A node chooses up to 2 stem relay connections, and fresh assignments in the next epoch limit long-term observation of one persistent route. [1]
A node's own transactions use the same stem edge within an epoch, while received transactions are mapped from an inbound edge to an outbound edge. Relay or diffuser status is selected pseudorandomly per node and epoch, not anew for every transaction; this addresses graph-learning and intersection attacks against the original Dandelion. [1]
The Dandelion++ paper is not an active Bitcoin BIP. BIP 156 described the older Dandelion and was closed without implementation; Bitcoin Core issue 20203 proposed Dandelion++, but it is now closed and lists no attached branch or pull request. Ordinary Bitcoin Core therefore does not use Dandelion++ by default. [3]
An attacker can attempt black-hole attacks, occupy Sybil positions, learn topology or correlate several transactions. A randomized fail-safe embargo timer switches a transaction to fluff if a node does not see it diffuse in time; this improves liveness, while timing and partial deployment still permit information leakage and delay. [4]
Dandelion++ can be combined with Tor or I2P, but it serves a different function. An anonymity network conceals a connection's transport path, whereas Dandelion++ changes transaction gossip between Bitcoin peers; neither mechanism alone fixes on-chain heuristics or coin-control mistakes. [1]
Verifying a claim requires a specific implementation, not merely the name. Inspect feature negotiation, construction of epochs and stem peers, inbound-edge mapping, the stem/fluff switch, embargo timer, fallback with incompatible peers, and measured anonymity, latency and partial-deployment behavior. [2]
For the clearest picture, read this entry together with Transaction, Mempool, Full Node, Bitcoin Privacy, Lightning Routing, Sybil Attack. The reverse links also lead from Bitcoin Anonymity Networks.
01Is Dandelion++ part of Bitcoin Core?+
Not according to the current public state. The older BIP 156 was closed without implementation, and Bitcoin Core issue 20203 for Dandelion++ is also closed with no attached branch or pull request. A paper must not be presented as an enabled feature of an ordinary node.
02Does Dandelion++ make Bitcoin transactions anonymous?+
No. It limits one method for inferring a transaction's network origin, but the transaction remains public on the blockchain and can reveal links through addresses, amounts, timing, coin selection or other network observations.