Snap2Pass: Consumer-Friendly Challenge-Response Authentication with a Phone

This paper proposes a challenge-response authentication system for web applications called Snap2Pass that is easy to use, provides strong security guarantees, and requires no browser extensions. The system uses QR codes which are small two-dimensional pictures that encode digital data. When logging in to a site, the web server sends the PC browser a QR code that encodes a cryptographic challenge; the user takes a picture of the QR code with his cell phone camera which results in a cryptographic response sent to the server; the web server then logs the PC browser in. Our user study shows that authentication using Snap2Pass is easy to learn and considerably faster than existing one-time password and challenge-response systems. By implementing our solution as an OpenID provider, we have made this scheme available to over 30,000 websites that use OpenID today. This paper also proposes Snap2Pay, an extension of Snap2Pass, to improve the usability and security of online payments. Snap2Pay allows a consumer to use one-time credit cards as well as the Verified by Visa or Mastercard SecureCode services securely and easily with just a snap of a QR code.