kiskis

Keep It Secret, Keep It Safe — a self-hostable, end-to-end encrypted file-sharing service inspired by Mozilla Send.

Files are encrypted in the browser before upload using AES-256-GCM. The server only stores ciphertext and a small amount of metadata. The decryption key lives in the URL fragment (#...), which browsers never send to the server.

Properties

• Zero runtime dependencies. TypeScript is the only build dependency. The server uses only Node's built-ins (node:http, node:sqlite, node:crypto, node:fs). The browser uses only the Web Crypto API.
• End-to-end encryption. AES-256-GCM with a per-file 256-bit key. Filename and MIME type are encrypted too — the server never sees them in cleartext.
• Chunked. 1 MiB plaintext chunks with truncation-resistant AAD; per-chunk nonces.
• Optional password. Encrypts the file key with PBKDF2-SHA256(600,000 iters). Without the password, the link alone is useless.
• Per-file limits. Choose max downloads (1–100) and TTL (1 hour to 365 days). The reaper deletes ciphertext from disk once either limit is reached.
• Admin-gated uploads. Bearer tokens are provisioned by an admin (with TTL and revocation). Downloads remain public-by-link.

Requirements

• Node.js 24 or newer (uses the built-in node:sqlite module), or Docker.

Quickstart

Docker

Multi-arch images (linux/amd64, linux/arm64) are published to GHCR on every push to main and on tagged releases.

docker run -d \
  --name kiskis \
  -p 8787:8787 \
  -e ADMIN_PASSWORD=change-me \
  -v kiskis-data:/data \
  ghcr.io/incanta/kiskis:latest

Visit http://localhost:8787/admin to sign in and create an upload token.

Docker Compose

Save the following as compose.yaml:

services:
  kiskis:
    image: ghcr.io/incanta/kiskis:latest
    container_name: kiskis
    restart: unless-stopped
    ports:
      - "8787:8787"
    environment:
      ADMIN_PASSWORD: ${ADMIN_PASSWORD:?set ADMIN_PASSWORD in .env}
      # SECURE_COOKIES: "true"     # enable when serving over HTTPS
      # MAX_FILE_BYTES: "2147483648"
    volumes:
      - kiskis-data:/data

volumes:
  kiskis-data:

Create a .env next to it (Compose auto-loads it) and start:

echo "ADMIN_PASSWORD=change-me" > .env
docker compose up -d

To update later: docker compose pull && docker compose up -d.

From source

cp .env.example .env
# edit .env, set ADMIN_PASSWORD at minimum
yarn install
yarn build
yarn start

Visit http://localhost:8787/admin to sign in and create an upload token.

Environment

Var	Default	Purpose
ADMIN_PASSWORD	(required)	Bootstrap password for the admin account. Changes to this rotate the stored hash on next login.
PORT	8787	HTTP port.
DATA_DIR	./data	Where the SQLite DB and ciphertext blobs live.
SECURE_COOKIES	false	Set to true when serving over HTTPS.
MAX_FILE_BYTES	2147483648	Plaintext size cap. Hard-clamped at 2 GiB.

Screenshots

Upload requires an admin-provisioned auth token to prevent unwanted usage:

Admin interface:

Upload interface:

Client-side password protection:

Download interface:

Security model

• The decryption key never reaches the server. It is generated in the browser, encoded into the URL fragment (#k1.<key> or #p1.<salt>.<wrapNonce>.<wrappedKey>), and browsers do not send fragments in HTTP requests.
• The server stores: ciphertext blobs, encrypted metadata, base nonces (random per-file), chunk counts, and policy flags. It does not store filenames, MIME types, the file key, the password, or any password-derived material.
• Downloading consumes one of the file's allowed downloads at the moment the user confirms — wrong password attempts do not consume downloads.
• File and chunk identifiers are random base64url strings, not enumerable.
• Admin sessions are random opaque tokens stored server-side, set as HttpOnly; SameSite=Strict cookies.
• Upload tokens are random 32-byte secrets shown to the admin once on creation; only an 8-character prefix is retained for display thereafter.

Limitations

• Browser-side downloads accumulate decrypted plaintext in memory before triggering the save (no third-party stream-saver library). Files up to ~1 GiB are practical on typical desktops.
• No anti-abuse rate limiting beyond admin-token gating. Add a reverse proxy (nginx, Caddy) if exposing to the public internet.
• HTTPS is recommended — Secure cookies and protected fragments rely on a trustworthy transport.