I agree that using C is a really dumb idea for anything security sensitive. It's rather curious the website says it's written in C against the libbitcoin libra

I agree that using C is a really dumb idea for anything security sensitive. It's rather curious the website says it's written in C against the libbitcoin library, as libbitcoin is a C++ library that doesn't even export C headers. As to their identities, I suspect it's the same people (Amir Taaki and friends) who are doing Dark Wallet. I rather doubt that as I haven't heard anything about Slur from that group - as Dark Wallet Chief Scientist they pretty much always run new ideas past me. Secondly they already have a better protocol for paying for information that that I and Amir Taaki developed: https://github.com/unsystem/paypub https://github.com/unsystem/paypub PayPub uses a non-interactive revealing stage to avoid the need for the trusted escrow agents that Slur claims to use. re: Dark Wallet, keep in mind it's still officially an alpha undergoing testing prior to release, but its CoinJoin mixer gets regular usage, mixing what seems to be in the region of a few thousand dollars worth of bitcoins every day on average. It is the only CoinJoin implementation I know of with any usage, other than the known to be badly broken blockchain.info one that doesn't provide any privacy. Recommending people use it to donate anonymously is quite reasonable.