---
title: Encrypted Pages
description: Client-side page encryption with Web Crypto — AES-256-GCM, PBKDF2-SHA-256, zero plaintext in the static output.
---

Any docs page can be password-protected. The rendered page (text, code blocks,
images — everything after Markdown and Expressive Code processing) is encrypted
at build time and decrypted in the browser with the Web Crypto API. The static
output contains ciphertext only — never the password, never the plaintext body.

## Cryptography

| Property | Value |
| --- | --- |
| Cipher | AES-256-GCM (authenticated — tamper-proof, integrity-checked) |
| Key derivation | PBKDF2-SHA-256, 310,000 iterations (OWASP recommendation) |
| Salt / IV | Random 16-byte salt, random 12-byte IV per build |
| Scope binding | AAD `celplume-protected-content:1:page:<id>` — ciphertext cannot be replayed on another page |
| Plaintext leaks | None — RSS carries no bodies; `/&lt;id&gt;.md` and `llms-full.txt` replace encrypted pages with a notice |

## Usage

```mdx
---
title: Private notes
encrypted: true
password: 'a-strong-password'
passwordHint: 'My favorite editor'
---

# This content ships encrypted

Everything below the frontmatter is encrypted at build time.
```

| Field | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| `encrypted` | `boolean` | no | `false` | Marks the page as encrypted |
| `password` | `string` | **yes** | — | Unlock password; an empty password fails the build (fail-closed) |
| `passwordHint` | `string` | no | — | Hint shown under the password field |

## Unlock flow

1. The visitor opens the page and sees the unlock gate.
2. The password derives the AES key locally (PBKDF2, 310k iterations) and
   decrypts the payload; GCM authentication rejects wrong passwords and
   ciphertext copied from other pages.
3. The decrypted HTML replaces the gate, and the Docs Kit runtime re-binds
   interactive components inside it.
4. The unlocked content is remembered in `sessionStorage` for 30 minutes —
   navigating away and back does not ask again. Passwords are never stored.

## Notes

- The table of contents of an encrypted page is empty until unlock (there are
  no headings to index).
- Pagefind indexes only the gate, not the encrypted body.
- Keep secrets out of `description` frontmatter — it stays plaintext for
  search engines and feeds.
- Forgetting the password is unrecoverable: the key exists only while the
  visitor types it.