Quote from: DannyHamilton on December 20, 2012, 06:54:45 AM

Quote from: Meni Rosenfeld on December 20, 2012, 06:49:58 AM

Quote from: piuk on December 19, 2012, 04:34:06 PM

Bitcoin addresses stored for notification purposes have been deleted. Addresses are now stored as a SHA 256 hash of the address, which removes the ability to lookup a wallet by bitcoin address.

It does not. If that address has received any payment, it's trivial to brute force SHA256 hashes of all addresses on the blockchain until you find a match. If you're serious about preventing lookup by address, use a slow hash.

The secret salt used in the hash should prevent brute force of all addresses.

Quote from: piuk on December 19, 2012, 05:11:27 PM

. . . Addresses are hashed with a secret. With access to the secret it would be possible to hash every bitcoin address with a none zero balance and use that to compare against subscribed hashes to determine addresses in a wallet. The sacrifice of some anonymity when notifications are enabled has always been stated https://blockchain.info/wallet/anonymity. However it is no longer possible for admins to lookup an arbitrary wallet by address.

My comment didn't make sense anyway, I got the process reversed. If the secret is unknown to admins it should work.