Building a Privacy-First URL Shortener on Blockchain

Description and use

A privacy‑first URL shortener that encrypts links client‑side and stores them on the Cronos blockchain, preventing server‑side visibility and tracking.

Problem

Traditional URL shorteners log user data, track browsing patterns, and sell data, creating privacy risks and a single point of failure.

Outcome

Cryptly provides a privacy‑first URL shortener where the server never sees the destination URL, no tracking occurs, and data is stored immutably on a blockchain, reducing risk of data leaks and censorship.

Workflow

• Generate a random IV and AES‑GCM key in the browser.
• Encrypt the destination URL with Web Crypto API.
• Send the ciphertext to a Cloudflare Worker endpoint.
• Store the ciphertext on the Cronos blockchain via the worker.
• When a user visits the short link, the worker retrieves the ciphertext from the blockchain.
• The browser decrypts the ciphertext locally using the same key and IV.
• Redirect the user to the decrypted URL.

Evidence

Encrypted URL stored on Cronos blockchain

Source

Server never sees destination

Source