Tumblebit Server Demo
Use at your own risk.
About tumblebit.network
tumblebit.network is a classic Bitcoin tumbler, mixing together the transfer of one bitcoin from each of n distinct payers (Alice) to n distinct payees (Bob). TumbleBit is run with the payment phase shrunk to 30 seconds, so the protocol runs in epochs that require two blocks added to the blockchain. tumblebit.network provides k-anonymity within an epoch: no one, not even the Tumbler, can link one of the k transfers that were successfully completed during the epoch to a specific pair of payer and payee (Alice, Bob).
Tumblebit Protocol Overview
TumbleBit replaces on-blockchain payments with off-blockchain RSA-puzzle solving, where Alice pays Bob by providing Bob with the solution to a blinded RSA-puzzle. The puzzle z is generated through interaction between Bob and Tumbler (the Tumblebit server) , and solved through an interaction between Alice and Tumbler . Each time a puzzle is solved, 1 bitcoin is transferred from Alice to the Tumbler and finally on to Bob.

Tumblebit: An Untrusted Bitcoin-Compatible Anonymous Payment Protocol
This paper, authored by Ethan Heilman, Leen AlShenibr, Foteini Baldimtsi, Alessandra Scafuro and Sharon Goldberg, presents TumbleBit, a new uni- directional unlinkable payment protocol that is fully com- patible with today’s Bitcoin protocol. TumbleBit allows parties to make fast, anonymous, off-blockchain payments through an untrusted intermediary called the Tumbler: no one, not even the Tumbler, can link a payment from its payer to its payee. Every payment made via TumbleBit is backed by bitcoins, and comes with a guarantee that Tumbler can neither violate anonymity, nor steal bitcoins, nor “print money” by issuing payments to itself.
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