Early alpha: monero-like linkable ring signatures in Ethereum, can do up to 3 pubkeys within 3.1m ga

[mjsrs]

vbuterinEthereum - Vitalik Buterin[S] 9 points an hour ago

Basically, this allows for the creation of anonymizing mixers on top of Ethereum, which have the benefit of:

1. Making currency transactions more privacy-preserving, particularly if you send through multiple "mixers"
2. Allowing for privacy-preserving identity systems, where if party B trusts/has KYCd/has verified actors with pubkeys P[1], P[2], P[3], then A can convince B that A is one of those three identities but without showing which one
3. Anonymized blockchain-based voting (but not-coercion-resistant; unfortunately I think nothing on blockchains is)

The linkability feature means that you can detect double-signatures made with the same key, which is what allows it to be used in currency anonymization.

Beware of the following two caveats:

1. This has totally not been security-reviewed; it has some test cases here but that's about it, this is still very very raw.
2. If actually using this in production, make sure to avoid accidentally turning the ether address that you use to pay transaction fees into a de-anonymization vector.

source:
https://www.reddit.com/r/ethereum/comments/3tappe/early_alpha_monerolike_linkable_ring_signatures/