Steve Bellovin posted this on another list, hattip to him. http://www.forbes.com/sites/andygreenberg/2013/04/12/zerocoin-add-on-for-bit... For those following Bitcoin this is news. Matthew Green writes: For those who just want the TL;DR, here it is: Zerocoin is a new cryptographic extension to Bitcoin that (if adopted) would bring true cryptographic anonymity to Bitcoin. It works at the protocol level and doesn't require new trusted parties or services. With some engineering, it might (someday) turn Bitcoin into a completely untraceable, anonymous electronic currency. http://blog.cryptographyengineering.com/2013/04/zerocoin-making-bitcoin-anon... (iang adds:) Bitcoin is psuedonymous but traceable, which is to say that all transactions are traceable from identity to identity, but those identities are psuedonyms, being (hashes of) public keys. This is pretty weak. In contrast, Chaumian blinding was untraceable but typically identified according to an issuer's regime. Because Chaumian mathematics required a mint, this devolved to trusted/identified, so again not as strong as some hoped. Bitcoin fixed this 'flaw' by decorporating the mint into an algorithm. This suggests a new axis of distributed. But Bitcoin lost the untraceability in the process, thus rendering it a rather ridiculous attempt at privacy, as the entire graph was on display. Bitcoin is more or less worse at privacy than Chaumian cash ever was. The holy grail in Chaumian times was untraceable & unidentifiable, to which Bitcoin added distributed. This paper by Miers, Garman, Green & Rubin suggests untraceable & psuedonymous & distributed is possible: http://spar.isi.jhu.edu/~mgreen/ZerocoinOakland.pdf (I haven't as yet read the paper so there may be killer details in there.) iang _______________________________________________ cryptography mailing list cryptography@randombit.net http://lists.randombit.net/mailman/listinfo/cryptography ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE