Email Masking in Ncurses Applications

The log scrolled fast across the terminal. Names, timestamps, and full email addresses flashed like beacons. It was a breach waiting to happen.

Masking email addresses in logs is not optional. It’s a control that must be part of your pipeline before data leaves memory. When working with ncurses applications—where output streams are interactive—you need a method that is both performant and predictable.

Start with a pattern match. A simple regex for standard email formats anchors the detection step:

[\w\.-]+@[\w\.-]+\.\w+

This captures most real-world cases without overcomplicating parsing. Once matched, replace the local part and domain with fixed tokens or hash values. For ncurses, this step must happen before rendering to the window, inside your main loop or logging function, so nothing unmasked ever touches the screen.

In C with ncurses, intercept the string before wprintw() or related calls:

char masked[BUFFER_SIZE];
mask_emails(original, masked);
wprintw(win, "%s", masked);

The mask_emails() function should run in O(n) time. Avoid heap allocations on each call, and keep preprocessing inline with your UI update cycle. For large volumes, precompile your regex once at startup, and reuse it.

Masking is more than a security gesture. It prevents accidental leaks when logs get scraped, archived, or sent to monitoring systems. With ncurses, every refresh is a chance for exposure. Your goal: sanitize in code, always upstream.

If compliance rules apply, document the masking logic and test it with edge cases—subdomains, plus-addresses, unusual TLDs. Build automated checks to verify that no unmasked addresses appear in saved logs or in-terminal displays.

Security in terminal UIs doesn’t have to be slow or complex. Done right, email masking with ncurses is a clean function call in the right place.

See it live, running in minutes, with prebuilt masking hooks at hoop.dev.