The Lore-Book

ᚠ What is Durin's Door?

Durin's Door is a zero-knowledge encrypted file-sharing web application. Like the ancient gate of Moria — it reveals itself only to those who know the word — Durin's Door encrypts your files entirely in your browser before they ever reach the server. The key lives only in the URL fragment, which is never sent to the server.

• Zero-knowledge encryption — AES-256-GCM, key stays in the URL fragment (#), never sent to the server
• Auto-expiry — links vanish after the time you set
• Download limits — restrict to N downloads and the door seals itself
• Optional password — adds a verification gate atop the key
• Handshake mode — peer-to-peer ECDH key exchange, no shared URL needed
• Zero server-side decryption — the server stores encrypted blobs only

ᚢ How to Share a File

To place an artifact in the vault, drag a file onto the door — or click it to browse. The door will encrypt your file in-browser, upload the ciphertext, and carve a link.

1. Drag or click the door on the home page to select your file
2. Set options — expiry, download limit, optional password
3. Click “Send Through the Door” — your browser encrypts with AES-256-GCM before upload
4. Copy the link — the decryption key is in the #fragment, invisible to the server

ᚱ How to Download

The bearer of the link visits the download page. The door presents what lies within. If a password was set, the door asks for the word. Speak truly, and it opens. Decryption happens entirely in your browser — plaintext never touches the server.

1. Open the link — the download page shows file details
2. Enter password (if required) — verified locally against a hash
3. Click “Open the Door & Download” — encrypted blob fetched, decrypted in browser, saved to device

ᚨ Handshake Mode — Peer-to-Peer Transfer

Handshake Mode enables direct peer-to-peer encrypted transfers without sharing a URL. The receiver generates a short pairing code; the sender enters it. An ECDH (P-256) key exchange derives a shared secret — the server never sees the key.

1. Receiver clicks “Handshake” → gets a 6-character code (e.g. GANDALF)
2. Receiver shares the code with the sender verbally or via any channel
3. Sender enters the code on the send page — ECDH keys are exchanged
4. Both see a verification phrase — 3 Tolkien words derived from the shared secret. Confirm they match!
5. Sender uploads file — encrypted with the ECDH-derived AES key
6. Receiver auto-downloads — decrypted in their browser with the same derived key

ᛊ Security & Encryption

• AES-256-GCM — authenticated encryption detects tampering
• Unique key per share — compromise of one share exposes nothing else
• ECDH P-256 — Handshake keys derived in-browser, never transmitted
• Browser-side decryption — plaintext never written to any server
• Auto-expiry — expired files are purged from storage
• Zero-knowledge — the server stores only encrypted blobs

ᛏ Install the CLI

Durin's Door also comes as a command-line tool — a single binary, no dependencies. Download it from GitHub Releases or use one of the incantations below.

ᛈ Server CLI Reference

The self-hosted server encrypts files locally with AES-256-GCM, stores them on disk, and serves them over HTTP with optional Cloudflare/ngrok tunneling. All incantations of the durins-door command:

durins-door server [flags]

durins-door share [flags] <file>

durins-door download <url>

Download and decrypt a shared file from a remote Durin's Door server. The encryption key is extracted from the URL fragment.

durins-door upload <file>

Upload a file to a remote Durin's Door server. Requires --api-token or the DURINS_DOOR_TOKEN environment variable.

durins-door send <file> --to <CODE>

Send a file to a waiting receiver via ECDH P-256 handshake against a remote server. Both parties see a 3-word Tolkien verification phrase to confirm no man-in-the-middle.

durins-door receive

Wait for a peer to send you a file via ECDH handshake. Generates a Tolkien-word pairing code, then auto-downloads and decrypts the file when the sender uploads it. Times out after 10 minutes.

Global flags (all commands)

ᛞ Using the CLI with durinsdoor.io

The CLI talks directly to durinsdoor.io by default — no self-hosted server needed. Encrypt locally, upload ciphertext to the cloud. Zero-knowledge — the server never sees your key or plaintext.

The CLI connects to https://durinsdoor.io by default. Override with --server-url to point at a self-hosted server or local dev instance.