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Executive Summary:
The SharedCoin mixing service provided by Blockchain.info offers only limited privacy to users due to weaknesses in its design. Bitcoin users should carefully consider their privacy requirements and evaluate other mixing services if they require serious privacy guarantees. A tool for analyzing SharedCoin and other CoinJoin-based mixing protocols will be released approximately two weeks following this advisory to allow SharedCoin users adequate time to protect their privacy.
The SharedCoin mixing service provided by Blockchain.info offers only limited privacy to users due to weaknesses in its design. Bitcoin users should carefully consider their privacy requirements and evaluate other mixing services if they require serious privacy guarantees. A tool for analyzing SharedCoin and other CoinJoin-based mixing protocols will be released approximately two weeks following this advisory to allow SharedCoin users adequate time to protect their privacy.
http://www.coinjoinsudoku.com/advisory/