Quote from: MagicalTux on January 21, 2013, 11:25:00 PM

Quote from: casascius on January 21, 2013, 11:05:48 PM

If MtGox could make it so that you could add your PGP public key and then configure your account such that bitcoin withdrawals require PGP signature of a pre-generated message that contained the destination bitcoin address, MtGox would have undisputable conclusive proof in the event of a disagreement as to whether a withdrawal was authorized.

We considered this, but the lack of proper PGP lib (the only few libs around will try to create stuff in $HOME and doesn't allow us to store/provide the public keys easily) or appropriate technical documentation on the signature format (it mostly says "read the source") forced us to delay this.

Glad to see you are at least considering it. For the record if/when you ever implement a PGP signed message system I would prefer it be in addition to 2FA. I.e. withdraw requires a PGP signed message PLUS sucessful 2FA challenge. The PGP signed message creates irrevocable proof of the transaction and the 2FA (google authenticator) provides additional security in the event the PGP key is compromised. While your at it throw in the ability to create multiple logins (w/ different security permissions) for a single account and optional dual authentication (not to be confused with 2FA) for withdrawals and you would have better security than most corporate banking platforms!

Also since you are reading this thread .... Generating a MtGox code can be properly protected by 2FA challenge (I love it you are one of the few exchanges which do it RIGHT) however one can view the "redeem code" page without 2FA authentication. This create a potential method to compromise codes before redeemed. User generates a code and before the counterparty redeems it the attacker (possibly alerted due to compromised email) logs in and redeems the code. There are two simple solutions (one simpler and more limited). The easiest method is perform a 2FA challenge when viewing the redeem code page. The more comprehensive option would be to allow viewing the page but the code is redacted. User can redeem code but clicking "view code" results in a 2FA challenge.