Evernote is taking a few big steps to help users lock down their accounts, including optional two-step authentication.The new security measures follow a "coordinated" attack on the note-taking service last March, in which hackers gained access to usernames, email addresses, and encrypted passwords. After the attack, Evernote required all 50 million of its users to change their passwords.Two-step authentication requires the use of a smartphone to prove your identity when logging in on a new device. During sign-in, Evernote sends a text message with a verification code, which must be entered on the new device. You can also generate a code using an authentication app, such as Google Authenticator for Android or iOS. Evernote says it will provide one-time backup codes for offline use while traveling.The downside to two-step authentication, as Evernote points out, is that you risk being locked out of your account if you lose your phone. Also, services that tie into Evernote will require a special application password, which you can set up through Evernote. (For more on the basics of two-step authentication, check out PCWorld's primer.)For now, two-step authentication is only available to Evernote Premium and Business customers, but it will be available to all users once Evernote feels comfortable supporting it more broadly.Two-step authentication isn't the only new security tool Evernote is offering. Starting now, all users can view their access history, which shows the last 30 days of use, including locations and IP addresses. If your account's been accessed from a strange location, or an unknown device, it could be a sign of a security breach.Users can also view a list of authorized applications, and revoke access through Evernote's Web interface. This is useful if your computer is lost or stolen, because it forces a fresh login the next time someone tries to use Evernote on that device.The extra security measures should provide some peace of mind for users who rely on Evernote for business, especially because the service can be used to store receipts and other sensitive data. The launch of two-step authentication follows a trend set by other major Web firms, including Twitter, Microsoft, Apple, Facebook, and Google.