Bank of America (BofA) has launched a new service called SafePass, adding another layer of security to online banking transactions. Using authentication technology developed by VeriSign, SafePass sends a 6-digit code to a customer's mobile phone; the code can only be used once and expires 10 minutes after being sent.

BofA customers can elect to use SafePass codes for certain types of online banking activities, such as logging on from a new computer or authorizing transfers of funds.

SafePass will be available to BofA customers in most U.S. states this week.

Bank of America said that it hopes SafePass will help crack down on malicious software attacks, which mine computers for user name and password information.