Building a Privacy-First URL Shortener on Blockchain

Description and use

The author built Cryptly, a privacy-first URL shortener using Cronos blockchain and client-side encryption. This prevents server-side tracking and eliminates the risk of centralized database hacks.

Problem

Traditional URL shorteners log user IPs, timestamps, user agents, and destination URLs, track browsing patterns, sell data to advertisers, and maintain centralized databases that are vulnerable to hacking.

Outcome

A privacy-first URL shortener that prevents server-side tracking, eliminates centralized database risks, and offers censorship resistance through blockchain storage and client-side encryption.

Workflow

• Client-side encryption of the destination URL using AES-GCM via Web Crypto API.
• Storage of the encrypted URL on the Cronos blockchain.
• Browser fetches the encrypted data from the blockchain.
• Local decryption of the URL in the browser using Web Crypto API.
• Redirection to the destination URL without server-side visibility.

Evidence

Server never sees destination URLs

Source

No database to leak

Source