A better privacy on the blockchain

A quick overview of privacy on the blockchain: low privacy, blockchain analysis, and the methods to improve the analysis resistance.

Transcript

1. A better privacy on the blockchain a quick practical overview Sergey Kazenyuk St. Petersburg Cryptography Meetup, 18 Feb 2016
2. Blockchain is transparent
3. Blockchain analysis https://www.blockseer.com/g/ve22fjOfibo – Flow of MtGox coins from the 424,242 BTC (proof-of-reserves) transaction
4. Attempts to improve analysis resistance What: • Linkability • Traceability How: • Use each address only once • Coin mixers • Merge avoidance • CoinJoin • Ring signatures • One-time keys • Zero Knowledge Proofs
5. Linkability: one-time addresses https://blog.ethereum.org/2016/01/15/privacy-on-the-blockchain/
6. Traceability (sk, pk) pk pk pk pk pk https://cryptonote.org/inside#untraceable-payments Ron Rivest, Adi Shamir, and Yael Tauman. How to leak a secret, ASIACRYPT 2001 Fujisaki, Eiichiro; Suzuki, Koutarou (2007). "Traceable Ring Signature". Public Key Cryptography: 181–200
7. Where and How • CryptoNote: Ring signatures, One-time keys (cryptonote.org) ◦ Bytecoin: bytecoin.org, Monero: getmonero.org, Boolberry: boolberry.org, Aeon • Ethereum smartcontract: Ring signatures ◦ github.com/ethereum/serpent/blob/develop/examples/ecc/ringsig.se • ZCash: Zero Knowledge Proofs (z.cash)
8. CryptoNote Transaction https://cryptonote.org/inside#standard-transaction
9. Q&A @sergeykazenyuk kazenyuk@gmail.com PGP: 0829 D006 C93A 3611 | keybase.io/ska
10. Some references General https://blog.ethereum.org/2016/01/15/privacy-on-the-blockchain/ https://bitcoinmagazine.com/articles/blockchain-meets-big-data-realtime-analysis-1435183048 Merge avoidance https://medium.com/@octskyward/merge-avoidance-7f95a386692f Ring signatures https://cryptonote.org/whitepaper.pdf https://downloads.getmonero.org/whitepaper_review.pdf Zero Knowledge http://www.ieee-security.org/TC/SP2015/papers-archived/6949a287.pdf