Building a Privacy-First URL Shortener on Blockchain

Description and use

The author built Cryptly, a URL shortener using Cronos blockchain and client-side AES-GCM encryption. This prevents server-side tracking and protects data from leaks via centralized databases.

Problem

Traditional URL shorteners log user IPs, timestamps, user agents, and destination URLs, tracking browsing patterns and selling data to advertisers. Additionally, centralized databases are vulnerable to hacking.

Outcome

A privacy-first URL shortener that eliminates server-side tracking and central database risks by using client-side encryption and blockchain storage.

Workflow

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

Evidence

Server never sees destination URLs

Source

No database to leak

Source