Quote from: Abrosim Adderiy on April 22, 2013, 08:42:51 AM

I would like to keep backup of my wallet on paper, but that's impossible or at least impractical when the bitcoind keeps creating new addresses for "change". I know it is possible in theory to do it by sending the change back to the sending address. And I know there are privacy implications when doing this. But I care more about security than anonymity in my case.

Is there an option to turn off "change" addresses in bitcoind (the original Satoshi client)?

If you are using bitcoind and creating your own user interface, then you can create raw transactions and sent the change wherever you like.

If you are using the Bitcoin-Qt interface, then as far as I know there is no way to control where the change goes. You should look into some other wallet for that purpose.

If you care most about security, you'll want to be aware that with brand new, never before used, addresses the private key is protected from the Bitcoin Address by 3 cryptographic algorithms (ECDSA, SHA-256, and RIPEMD-160). Once a transaction is sent using value that was previously received at an address, the private key is only protected from the address by ECDSA.

At the moment this is plenty of protection. There is currently no known feasible way to reverse ECDSA and figure out the private key from the public key. However, with a previously unused address a flaw would have to be discovered in all three algorithms nearly simultaneously, which is extremely unlikely and would allow time for bitcoin to implement a replacement function and time for you to move your coins to the new functionality. If you re-use addresses, then a flaw would only have to be discovered in the future in ECDSA for someone to potentially be able to access your bitcoins.