Anonymity for Bitcoin with accountable mixes ( Full version )

We propose Mixcoin, a protocol to facilitate anonymous payments in Bitcoin and similar cryptocurrencies. We build on the emergent phenomenon of currency mixes, adding an accountability mechanism to expose theft. We demonstrate that incentives of mixes and clients can be aligned to ensure that rational mixes will not steal. Our scheme is efficient and fully compatible with Bitcoin. Against a passive attacker, our scheme provides an anonymity set of all other users mixing coins contemporaneously. This is an interesting new property with no clear analog in better-studied communication mixes. Against active attackers our scheme offers similar anonymity to traditional communication mixes.

[1]  David Chaum,et al.  Blind Signatures for Untraceable Payments , 1982, CRYPTO.

[2]  Ghassan O. Karame,et al.  Evaluating User Privacy in Bitcoin , 2013, Financial Cryptography.

[3]  Matthew Green,et al.  Zerocoin: Anonymous Distributed E-Cash from Bitcoin , 2013, 2013 IEEE Symposium on Security and Privacy.

[4]  Moni Naor,et al.  Bit Commitment Using Pseudo-Randomness , 1989, CRYPTO.

[5]  Bart Preneel,et al.  Towards Measuring Anonymity , 2002, Privacy Enhancing Technologies.

[6]  Emin Gün Sirer,et al.  Majority Is Not Enough: Bitcoin Mining Is Vulnerable , 2013, Financial Cryptography.

[7]  Kazue Sako,et al.  Receipt-Free Mix-Type Voting Scheme - A Practical Solution to the Implementation of a Voting Booth , 1995, EUROCRYPT.

[8]  Nick Mathewson,et al.  Tor: The Second-Generation Onion Router , 2004, USENIX Security Symposium.

[9]  Malte Möser.  Anonymity of Bitcoin Transactions An Analysis of Mixing Services , 2013 .

[10]  Philippe Golle,et al.  Reputable Mix Networks , 2004, Privacy Enhancing Technologies.

[11]  Fergal Reid,et al.  An Analysis of Anonymity in the Bitcoin System , 2011, PASSAT 2011.

[12]  Jeremy Clark,et al.  On the Use of Financial Data as a Random Beacon , 2010, EVT/WOTE.

[13]  Adi Shamir,et al.  Quantitative Analysis of the Full Bitcoin Transaction Graph , 2013, Financial Cryptography.

[14]  Ronald L. Rivest,et al.  Electronic Lottery Tickets as Micropayments , 1997, Financial Cryptography.

[15]  Elaine Shi,et al.  Bitter to Better - How to Make Bitcoin a Better Currency , 2012, Financial Cryptography.

[16]  Nick Mathewson,et al.  Anonymity Loves Company: Usability and the Network Effect , 2006, WEIS.

[17]  Joshua A. Kroll,et al.  The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries , 2013 .

[18]  Roger Dingledine,et al.  From a Trickle to a Flood: Active Attacks on Several Mix Types , 2002, Information Hiding.

[19]  G. Jolly.  EXPLICIT ESTIMATES FROM CAPTURE-RECAPTURE DATA WITH BOTH DEATH AND IMMIGRATION-STOCHASTIC MODEL. , 1965, Biometrika.

[20]  Eli Ben-Sasson,et al.  Zerocash: Decentralized Anonymous Payments from Bitcoin , 2014, 2014 IEEE Symposium on Security and Privacy.

[21]  George Danezis,et al.  Pinocchio coin: building zerocoin from a succinct pairing-based proof system , 2013, PETShop '13.

[22]  Nicolas Christin,et al.  Traveling the silk road: a measurement analysis of a large anonymous online marketplace , 2012, WWW.

[23]  David Chaum,et al.  Untraceable electronic mail, return addresses, and digital pseudonyms , 1981, CACM.

[24]  Jean-François Raymond,et al.  Traffic Analysis: Protocols, Attacks, Design Issues, and Open Problems , 2000, Workshop on Design Issues in Anonymity and Unobservability.

[25]  S A R A H M E I K L E J O H N,et al.  A Fistful of Bitcoins Characterizing Payments Among Men with No Names , 2013 .

[26]  Dogan Kesdogan,et al.  Stop-and-Go-MIXes Providing Probabilistic Anonymity in an Open System , 1998, Information Hiding.

[27]  Roger Dingledine,et al.  Blending Different Latency Traffic with Alpha-mixing , 2006, Privacy Enhancing Technologies.