BurnAfterRead

Privacy-first, end-to-end encrypted, self-destructing data sharing.

Share sensitive text or files via links that expire after being read. No accounts. No tracking. The server never sees your decryption key.

https://burnafterread.casablanque.com

Security details: https://burnafterread.casablanque.com/security

---

Features

• End-to-end encryption (AES-GCM 256) — encrypted in your browser before upload
• Zero-knowledge architecture — server never sees the decryption key
• Burn after read — data is destroyed after access
• File support — up to 5 MB
• TTL expiration — 1 hour, 24 hours, or 7 days
• Limited views — 1, 3, or 10 reads
• Revoke anytime — delete a drop before it's read using the delete token
• Paranoid mode — always deletes on first access, returns not_found instead of expired/burned
• Atomic reads — Durable Objects prevent double-reads under concurrent requests
• Rate limiting — 20 requests per IP per 60 seconds on all API routes
• Automatic cleanup — expired drops purged from D1 and R2 every hour

---

How it works

plaintext → AES-GCM encrypt (browser) → ciphertext → Cloudflare R2
                    ↓
             key stays in URL fragment (#k=...)
             never sent to server

When someone opens the link:

URL fragment → key parsed locally → fetch ciphertext → decrypt in browser → plaintext

The URL looks like:

https://burnafterread.casablanque.com/d/<id>#k=<base64url-key>

id is sent to the server. k never leaves the browser — it's a URL fragment.

---

Architecture

Layer	Technology
Frontend	React, Web Crypto API
Backend	Cloudflare Workers
Metadata	Cloudflare D1 (SQLite)
Blobs	Cloudflare R2
Concurrency	Durable Objects (DropAccessCoordinator)
Rate limiting	Durable Objects (RateLimiter, sliding window)
Cleanup	Workers Cron Trigger (hourly)

---

Read lifecycle

1. GET /api/drops/:id hits the Worker
2. Worker checks rate limit (DO-based, per IP)
3. Worker delegates to DropAccessCoordinator DO
4. Inside blockConcurrencyWhile (atomic):
   • Check TTL
   • Check views_left
   • Decrement counter
   • Fetch ciphertext from R2
   • If paranoid or last view → delete D1 record + R2 object
5. Return ciphertext to browser
6. Browser decrypts with key from URL fragment

---

Revoke lifecycle

1. Sender calls DELETE /api/drops/:id with { delete_token }
2. Worker delegates to DropAccessCoordinator DO
3. Inside blockConcurrencyWhile:
   • Fetch drop from D1
   • Hash provided token, compare with stored hash (constant-time)
   • Delete D1 record + R2 object
4. Link is immediately dead

---

Local development

npm install

# create local D1
npx wrangler d1 execute burnafterread-db --local --file=./migrations/0001_init.sql

# build frontend + start worker
npm run build
npx wrangler dev

Open:

http://localhost:8787

---

API

Create drop

POST /api/drops
Content-Type: application/json

{
  "ciphertext": "<encrypted payload as JSON string>",
  "ttl_seconds": 86400,
  "views": 1,
  "kind": "text",
  "size_bytes": 123,
  "paranoid": true
}

Response:

{
  "id": "AbCdEf1234",
  "delete_token": "<base64url token>"
}

---

Read drop

GET /api/drops/:id

Response:

{
  "ciphertext": "<encrypted payload>",
  "kind": "text"
}

Errors:

404 not_found
410 expired
410 burned
429 too many requests

---

Revoke drop

DELETE /api/drops/:id
Content-Type: application/json

{
  "delete_token": "<token from create response>"
}

Response:

{ "ok": true }

---

CLI

Send and receive drops directly from your terminal. Same zero-knowledge guarantees as the web app.

Install

npm install -g burnafter

Send

# send a file
burnafter send secret.txt

# send text inline
burnafter send --text "my api key"

# custom TTL and views
burnafter send config.env --ttl 3600 --views 1

# paranoid mode
burnafter send archive.zip --paranoid

Options:

Flag	Description	Default
--text <text>	Send text instead of file	—
--ttl <seconds>	Time to live	86400
--views <n>	Allowed reads	1
--paranoid	Delete on first access	false

Receive

# decrypt text to stdout
burnafter receive "https://burnafterread.casablanque.com/d/AbCdEf1234#k=..."

# save to specific file
burnafter receive "https://...#k=..." --out secret.env

The URL must be passed as a quoted string to prevent the shell from stripping the # fragment.

---

Security notes

• Encryption is client-side only — the server stores ciphertext, never plaintext
• The decryption key is in the URL fragment — it is never sent to the server by the browser
• No authentication — the link itself is the only access control; guard it accordingly
• Losing the link means losing the data — there is no recovery mechanism
• ttl_seconds is bounded to 60 seconds–7 days; views to 1–10
• All API responses include Content-Security-Policy, X-Frame-Options: DENY, and Referrer-Policy: no-referrer

---

License

MIT