Dropbox has rolled out two-factor authentication to protect users from having their account details stolen by hackers.
The cloud storage firm's file sharing service is one of the most popular on the internet.
Earlier this month, the company suffered a breach of its infrastructure when account holders reported receiving unwanted messages in email accounts used only for Dropbox communications.
The one-time passcode should increase security as they are much harder to intercept and expire quickly.
A security code can either be text to a mobile phone or generated by a mobile authenticator app.
Dropbox supports a number of different authenticator apps, including Google Authenticator for Android, iPhone, and BlackBerry; Amazon AWS MFA for Android and Authenticator for Windows Phone 7.
We're working on automated mechanisms to identify suspicious activity.
User will also need to upgrade their client to version 1.5.12. The settings can be activated via Dropbox's "Security" tab.
"Two-step verification is one of several steps that we're taking to enhance the security of your Dropbox," said Dan Wheeler on the company's blog.
The company has also created a way for users to view all active logins to their account using the Security tab. "We're working on automated mechanisms to identify suspicious activity," added Wheeler.
But early users of the system have complained the new security features are not quite ready.
One user, David W, said on the company's forum: "Someone didn't think this through. If my phone is lost, and I've lost my emergency backup code, there is currently NO WAY to recover your dropbox account. There really needs to be another method to recover the account."
