A standard QR code is a public object — anyone who scans it reaches whatever it points to, which is exactly right for menus and exactly wrong for patient forms, exam papers, guest-wifi-adjacent home networks, wedding photo albums, or the document meant for one client. A QR code with password protection closes that gap: the scan opens a gate, the gate checks a credential, and the content flows only to the intended audience. Here's how the protection layers work, which situations need which level, and the honest limits — including what a QR code cannot keep private.

== The Three Protection Architectures (From Lightest to Strongest) ==

"Protected QR code" means three different builds, and choosing correctly starts with knowing the stack:

1. The password page (the standard build).
   The code points to a page that asks for a password before revealing content. The QR itself carries no secret — it's a pointer to a gate. This is the right build for shared-album albums, wedding sites, class materials, and event programs: the audience is semi-private, the content is non-financial, and the password travels with the invitation ("password on the card beside the code").
2. The one-time or expiring code.
   Dynamic-code systems can limit a code to N scans or a time window — the exam-paper code that works for one class period, the coupon code with 200 redemptions. The credential is consumption-counting rather than a password, and it suits ticketed or metered distribution.
3. The authenticated link (identity-bound).
   The code opens a login (or app deep-link) that binds access to a specific account — patient portals, corporate documents, banking interfaces. The QR is pure convenience-entry; the security lives entirely in the authentication behind it.

The selection logic follows the content's sensitivity: convenience-tier content takes the password page, metered distribution takes count-limited codes, and anything regulated or financial belongs behind full authentication — where the QR is a doorway, never the lock.

== How to Build Each (The Practical Paths) ==

The password page — the most common need, with three build paths:

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