Following the thread from Instawallet about green address, we have decided to give it a try on MtGox.

When withdrawing on MtGox, you can check the option "Use green address" to cause your coins to be sent through the address 1LNWw6yCxkUmkhArb2Nf2MPw6vG7u5WG7q (or pass the option green=1 to the withdraw.php API).

We have however used a slightly different implementation than Instawallet here, ensuring there is never any coin remaining on this address, reducing the interest for "bad people" to guess its private key.

Each time a transaction is sent via our "green address", a first transaction is generated to send a random amount of bitcoins (larger than the total amount of coins withdrawn) to the address, then a second transaction is generated to get the coins "out". Transactions are always sent by pair and are broadcasted together.

This, however, causes transactions sent via the "green address" option to normal targets to take longer, as two transactions needs to be confirmed. Bitcoin services recognizing our green address will, however, be able to process those deposits in real time instead of waiting for confirmations.


We are thinking of rotating the MtGox green address once in a while, with new green address announced ~1 month in advance.


Any comment on this is welcome.