Password

A password is a secret string that controls access to systems and services. In the QR code context, Wi-Fi passwords are the most common use case. Scanning a Wi-Fi QR code auto-fills the password, eliminating manual entry of complex strings. Even a 16+ character random password can be entered instantly via QR code, balancing security and convenience.

However, QR codes have no built-in encryption. Any password stored in a QR code can be read in plaintext by anyone who scans it. This applies to Wi-Fi passwords, authentication tokens, API keys, and any other secret. A QR code displayed in a public space should be treated as public information.

Practical countermeasures vary by use case. For Wi-Fi sharing, isolate a guest network and rotate passwords regularly. For authentication, use one-time passwords or time-limited tokens to contain the impact of leaks. The safest approach is storing only a URL in the QR code and handling authentication on the linked web service.