---
title: Introduction
description: What shhh is, what it deliberately is not, and how the encryption works.
navigation:
  icon: i-lucide-info
---

Most "send me the password" moments end in a chat message that stays there forever. shhh is for the
other path: paste a secret, get a link, and have it disappear after a set number of reads or a
deadline — without trusting the server with the contents.

## How the encryption works

Everything happens in the browser, before anything is sent.

1. The browser generates a random 256-bit key.
2. It encrypts your text or file with **AES-256-GCM** using that key.
3. It sends only the ciphertext and an initialisation vector to the server.
4. The link you get back carries the key in its **fragment** — the part after `#`.

```
https://shhh.example.com/p/8f3c…#key=Ux7…
                        └─ sent to the server ─┘ └─ never sent ─┘
```

Browsers do not transmit the fragment in HTTP requests. The server receives the paste id, looks up
the ciphertext, and hands it back. It has no way to decrypt it — and neither would anyone who
obtained a dump of the database.

::note
Filenames are encrypted too, with a separate initialisation vector. MIME types are stored in clear
so the browser knows how to hand the file back to you.
::

### Optional password protection

You can add a password on top. It derives a second key with **Argon2id** (OWASP interactive
parameters), salted with the fragment key itself. Both the password *and* the link are needed to
decrypt — the server never sees the password and only records that one is required.

::note
A wrong password costs nothing. Your browser proves it derived the right key by sending a SHA-256 of
it, which the server checks in the same statement that spends the read — so a mistyped password is
refused before the counter moves. The server still never sees the password itself.
::

## The two tiers

|  | Anonymous | Signed in |
|---|---|---|
| Encryption | Zero-knowledge | Zero-knowledge |
| Content | Text only | Text and file uploads |
| Password protection | Yes | Yes |
| Default max retention | 7 days | 30 days |
| Track your pastes | No | Yes, from a dashboard |
| Share by email | Client-side `mailto:` | Server-side, at creation |

Anonymous stays deliberately minimal: no account, no follow-up, no management link. Counters and
history are features of the signed-in tier.

## What shhh is not

- **Not a team secret manager.** Multi-tenancy and organisation-shared vaults were evaluated and
  dropped. shhh is a pastebin with counters, not a Vault or Infisical replacement.
- **Not a file host.** Uploads are capped (2 MB by default), stored in PostgreSQL, and expire like
  everything else.
- **Not protection against a malicious operator.** A modified server could serve altered JavaScript.
  Self-hosting the instance you trust is the answer.

## Next

::card-group
  :::card
  ---
  icon: i-lucide-container
  to: /self-hosting/installation
  ---
  #title
  Install it

  #description
  Docker Compose, environment variables, first run.
  :::

  :::card
  ---
  icon: i-lucide-shield
  to: /self-hosting/security
  ---
  #title
  Security model

  #description
  What the server can see, and the one deliberate exception.
  :::
::