🔐 Secure Pastebin (Self-Hosted)

Self-hosted, zero-knowledge, end-to-end encrypted pastebin built with PHP, MySQL, Web Crypto API, and a responsive single-page UI.

Share sensitive text securely. Encryption happens in the browser before upload, the server stores ciphertext only, and the decryption key stays in the URL fragment (#...) so it is never sent to the server.

🌐 Live Demo: https://sphost.theazizi.ir
☁️ Cloudflare Worker version: https://github.com/TheGreatAzizi/Secure-Pastebin-Cloudflare-Worker

✨ Features

🔒 Client-side AES-256-GCM encryption using the native Web Crypto API
🛡️ Zero-knowledge architecture — server never receives plaintext, password, or key
🧾 Optional subject field included inside the encrypted payload
🔑 Optional password protection with PBKDF2 (100,000 iterations, SHA-256)
🔥 Burn after reading support
⏱️ Preset expiration plus custom expiration date & time
📝 Markdown authoring + rendering
- compact formatting toolbar in the composer
- Markdown is rendered after decryption only
🔗 Two share-link formats
- full link: /p/{id}#key
- short link: /#id:key
📋 Copy actions for full link, short link, and decrypted text
📱 Responsive UI with improved mobile layout
🌍 RTL-aware text handling for Persian / Arabic / Hebrew content
🔤 No external font CDN — uses a local Vazirmatn-based font stack
⚙️ Documented HTTP API with /api/docs

🔐 How the security model works

The browser generates or derives the encryption key locally.
The browser encrypts the payload locally using AES-256-GCM.
The server receives only:
- paste ID
- IV
- ciphertext
- metadata such as expiration / burn-after-read / password flag
The decryption key is kept in the URL fragment (#...). URL fragments are not sent in normal HTTP requests.
The recipient opens the link, downloads the encrypted payload, and decrypts it locally.

Important note

If the full share URL is lost, the message is not recoverable. The server cannot reconstruct the decryption key.

🧱 Current stack

Frontend: HTML, CSS, vanilla JavaScript
Crypto: Web Crypto API
Backend/router: PHP
Database: MySQL / MariaDB
Storage model: encrypted payload + metadata only

🆕 What is included in this version

Compared with the older README, the current app now includes compact share links, custom expiration timestamps, a Markdown toolbar and renderer, password strength feedback, an API docs page, updated responsive layout, and a local-font setup with no external font dependency. The older README you uploaded still documents the earlier API shape and older sharing format. fileciteturn0file0

🧩 Share link formats

Full share link

https://your-domain.com/p/AbCdEf1234567890#BASE64URL_KEY

Full share link with password flag

https://your-domain.com/p/AbCdEf1234567890#BASE64URL_SALT:pwd

Short share link

https://your-domain.com/#AbCdEf1234567890:BASE64URL_KEY

Short share link with password flag

https://your-domain.com/#AbCdEf1234567890:BASE64URL_SALT:pwd

ID compatibility

The backend currently accepts these ID formats:

legacy 32-character lowercase hex IDs
compact 16-character URL-safe IDs ([A-Za-z0-9_-]{16})

The UI currently generates the compact 16-character format by default.

📝 Encrypted payload format

The browser encrypts a JSON payload. Subject and content are both inside the encrypted blob.

Example logical structure before encryption:

{
  "subject": "Optional subject",
  "content": "Secret message with **Markdown** support"
}

The server never sees this plaintext object.

🚀 Installation

1) Database

Create a database, then import database.sql.

CREATE TABLE IF NOT EXISTS pastes (
    id VARCHAR(32) PRIMARY KEY,
    data TEXT NOT NULL,
    created_at BIGINT NOT NULL,
    expires_at BIGINT NOT NULL,
    burn_after_read TINYINT(1) DEFAULT 0,
    has_password TINYINT(1) DEFAULT 0,
    views INT DEFAULT 0
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE INDEX idx_expires ON pastes(expires_at);

2) Configure PHP

Edit the database constants in index.php:

const DB_HOST = 'localhost';
const DB_USER = 'your_db_user';
const DB_PASS = 'your_db_password';
const DB_NAME = 'your_db_name';

3) Upload files

Upload the project files to your web root.

/public_html/
├── .htaccess
├── api-docs.php
├── database.sql
├── index.html
├── index.php
├── LICENSE
├── README.md
├── script.js
└── style.css

4) Enable URL rewriting

Apache .htaccess used by the project:

RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]

RewriteRule ^ index.php [L]

5) Use HTTPS

crypto.subtle requires a secure context in production. Use:

HTTPS on your domain, or
localhost during local development

📁 Project structure

File	Purpose
`index.php`	router + API backend
`index.html`	single-page app UI
`script.js`	encryption, decryption, UI behavior, Markdown tools
`style.css`	responsive styling
`api-docs.php`	human-friendly API documentation page
`database.sql`	MySQL schema
`.htaccess`	Apache rewrite rules

🧠 Composer UI highlights

Secure message composer

optional subject
Markdown toolbar
multiline textarea
preset expiration dropdown
custom expiration datetime picker
password-protection toggle
burn-after-reading toggle
password strength meter

Decrypted result view

subject display
rendered Markdown output
copy decrypted text button
burn-after-read warning when applicable

✍️ Markdown support

Markdown is stored as plain text inside the encrypted payload and is rendered only after decryption.

Supported authoring helpers include:

Bold
Italic
~~Strikethrough~~
headings
quotes
bullet lists
numbered lists
links
inline code
fenced code blocks

This keeps the stored payload simple while still giving the recipient a readable result view.

🔌 API

Docs page

Once deployed, the built-in docs page is available at:

https://your-domain.com/api/docs

Base notes

API stores ciphertext only
API does not perform encryption for you
client must encrypt before sending data
password or raw key must never be sent to the server

Endpoints

Method	Route	Description
`GET`	`/api/health`	service health check
`GET`	`/api/options`	API capabilities, limits, routes
`GET`	`/api/docs`	HTML API documentation
`POST`	`/api/pastes`	create a paste
`POST`	`/api/pastes/{id}`	create a paste with a specific ID
`GET`	`/api/pastes/{id}`	fetch encrypted payload
`GET`	`/api/pastes/{id}/meta`	fetch metadata only
`POST`	`/api/create`	legacy create route
`GET`	`/api/get/{id}`	legacy read route

Limits

From the current backend:

minimum expiration: 300 seconds
maximum expiration: 31536000 seconds (365 days)
max encrypted payload size: 4 MiB

Supported create payload formats

You can create a paste using any of these shapes:

nested byte arrays

{
  "encryptedData": {
    "iv": [12, 34, 56],
    "data": [99, 88, 77]
  }
}

top-level byte arrays

{
  "iv": [12, 34, 56],
  "data": [99, 88, 77]
}

nested base64url strings

{
  "encryptedData": {
    "ivBase64": "AAECAwQFBgcICQoL",
    "dataBase64": "mYh3"
  }
}

top-level base64url strings

{
  "ivBase64": "AAECAwQFBgcICQoL",
  "dataBase64": "mYh3"
}

ivBase64url / dataBase64url are also accepted.

Create request fields

Field	Required	Description
`id`	optional	custom paste ID
`encryptedData` or equivalent	yes	ciphertext payload
`expiresIn`	optional	expiry in seconds
`customExpiresAt`	optional	exact Unix timestamp in seconds
`burnAfterRead`	optional	delete after first successful read
`hasPassword`	optional	indicates password is required on the client

If customExpiresAt is present, it overrides expiresIn.

Example: create a paste

curl -X POST https://your-domain.com/api/pastes \
  -H "Content-Type: application/json" \
  -d '{
    "id": "AbCdEf1234567890",
    "encryptedData": {
      "iv": [12, 34, 56, 78, 90, 12, 34, 56, 78, 90, 12, 34],
      "data": [189, 45, 78, 201, 156, 78, 33, 45]
    },
    "expiresIn": 86400,
    "burnAfterRead": false,
    "hasPassword": false
  }'

Example success response

{
  "success": true,
  "apiVersion": "1.2",
  "id": "AbCdEf1234567890",
  "expiresAt": 1735689600,
  "expiresIn": 86400,
  "burnAfterRead": false,
  "hasPassword": false,
  "url": "https://your-domain.com/p/AbCdEf1234567890",
  "retrieveUrl": "https://your-domain.com/api/pastes/AbCdEf1234567890",
  "metaUrl": "https://your-domain.com/api/pastes/AbCdEf1234567890/meta",
  "docsUrl": "https://your-domain.com/api/docs"
}

Example: fetch encrypted payload

curl https://your-domain.com/api/pastes/AbCdEf1234567890

Example response:

{
  "success": true,
  "apiVersion": "1.2",
  "id": "AbCdEf1234567890",
  "encryptedData": {
    "iv": [12, 34, 56, 78, 90, 12, 34, 56, 78, 90, 12, 34],
    "data": [189, 45, 78, 201, 156, 78, 33, 45],
    "ivBase64": "AAECAwQFBgcICQoL",
    "dataBase64": "mYh3"
  },
  "data": {
    "iv": [12, 34, 56, 78, 90, 12, 34, 56, 78, 90, 12, 34],
    "data": [189, 45, 78, 201, 156, 78, 33, 45]
  },
  "burnAfterRead": false,
  "hasPassword": false,
  "created": 1735603200000,
  "expiresAt": 1735689600,
  "views": 1
}

Burn-after-read behavior

When burnAfterRead is enabled, the first successful fetch from GET /api/pastes/{id} returns the ciphertext and then removes that paste from storage.

Metadata endpoint

curl https://your-domain.com/api/pastes/AbCdEf1234567890/meta

Example response:

{
  "success": true,
  "apiVersion": "1.2",
  "id": "AbCdEf1234567890",
  "shareUrl": "https://your-domain.com/p/AbCdEf1234567890",
  "retrieveUrl": "https://your-domain.com/api/pastes/AbCdEf1234567890",
  "created": 1735603200000,
  "expiresAt": 1735689600,
  "remainingSeconds": 86400,
  "burnAfterRead": false,
  "hasPassword": false,
  "views": 0
}

🧪 Health and options

Health

curl https://your-domain.com/api/health

Options

curl https://your-domain.com/api/options

/api/options returns API version, limits, presets, capabilities, endpoints, and notes.

🌐 Browser compatibility

Browser	Status
Chrome / Edge	✅
Firefox	✅
Safari	✅
Internet Explorer	❌

A secure context is required for the Web Crypto API.

🛡️ Security notes

Protected well

database leaks still expose ciphertext only
server admins do not have plaintext or keys
password material stays client-side
URL fragment is not sent to the backend

Not protected well

malware on sender or recipient device
leaked full share URLs
weak passwords chosen by users
copied plaintext after decryption
screenshots or shoulder surfing

Recommended operational practices

send password separately from the URL
use burn-after-read for highly sensitive messages
prefer long random passwords
use private browsing on shared devices
do not paste highly sensitive links into third-party chatbots or analytics tools

🎨 UX and design notes

improved composer layout for desktop and mobile
cleaner stacked settings cards for expiration and security options
compact Markdown toolbar
icon-only social links in the footer
consistent visual style shared by the app and API docs page

📌 Roadmap ideas

encrypted file attachments
QR code for secure links
separate key-sharing mode
OpenAPI / Swagger export
admin-only cleanup / moderation tools
theme switcher

🤝 Contributing

Issues and pull requests are welcome.

If you open a PR, try to keep these guarantees intact:

client-side encryption only
zero-knowledge storage model
no accidental leakage of key material to the server
backward compatibility for existing shared links where possible

📜 License

MIT — see LICENSE.

👤 Author

TheGreatAzizi

GitHub: @TheGreatAzizi
X: @the_azzi
Telegram: @luluch_code

⚠️ Disclaimer

This project is provided as is without warranty of any kind. You are responsible for your own deployment security, backups, SSL/TLS configuration, database hardening, and safe sharing of URLs and passwords.

Name		Name	Last commit message	Last commit date
.htaccess		.htaccess
LICENSE		LICENSE
README.md		README.md
api-docs.php		api-docs.php
database.sql		database.sql
index.html		index.html
index.php		index.php
script.js		script.js
style.css		style.css

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