For a business account at a Bitcoin exchange, either of two people need to be able to send bitcoins or withdraw. This account will be configured with two-factor authentication.

How can two of the business' staff, located in different offices, each have access to the account?

The exchange specifically will be with BitFloor using Google Authenticator OTP, but the same question would apply for using Mt. Gox, with Yubikey, for instance.

  • Apparently with YubiKey, the exchange needs to accommodate multiple OTP authentication devices. It looks like the only exchange to support multiple simultaneous Yubikey authenticators is Mt. Gox. The private key for Google Authenticator can be replicated so that doesn't have this restriction, as Daniel H answered below. – Stephen Gornick Aug 28 '12 at 18:16

With Google Authenticator, you scan a barcode into your phone and it generates a temporary 6-digit key every minute the app is open. If multiple people scan this barcode, they will all generate the same keys. Thus, all you need to do is have both people present when setting up two-step authentication (or save the barcode if they have incompatible schedules, but be sure to shred it later), and they will both be able to access the account whenever they want.

  • Oh, of course -- with Google Authenticator I can copy the QR code (e.g., screen shot if necessary) and then share that (in a secure manner) with each party that needs access. – Stephen Gornick Aug 28 '12 at 18:13

With Mt.Gox you can add multiple authenticators; while I'm not sure if you can add two copies of the same type of authenticator, it is worth a try.

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