In order to add funds to your Battle.net Balance, players will be required to have an Authenticator (physical or mobile) attached to their account. You can pick up Authenticators from the Blizzard store for $6.50, or you can download a free Mobile Authenticator app on your iPhone, iPod, Blackberry, Zune, or Android phone (from Google Play).
The forum post reads:
While we understand that this creates an extra step for players during the login process, we believe this added layer of account protection will help foster a safer auction house environment for all of our players.
When reports of Diablo 3 accounts getting hacked started to come out, Blizzard released a statement saying that, “We have yet to investigate a compromise report in which an authenticator was attached beforehand.” – meaning that Authenticators effectively removed the threat of hacking. However, we reported in late May that, “many players are claiming that they lost their accounts despite owning any of the three Authenticators.”
The online-only game play is also meant to curb abuse of the auction house, as Forbes reports:
…in order for this to work, there can’t be ANY chance of item duping or fake gear or any of the issues that plagued Diablo 2. In order to ensure this doesn’t happen, EVERYTHING in the game has to take place on Blizzard’s servers, as no amount of hacking should be able to produce faux items to sell in the store if everything is stored off-site. Always-on DRM is not in place for piracy’s sake, it’s for the good of the auction house.