Digital Certificates

Cryptography · Axiom Academy

REAL WORLD Digital Certificates How your browser knows a website is who it claims to be The Trust Problem on the Internet Imagine you're about to enter your credit card information on a website. How do you know the website is really who it claims to be? How do you know you're actually talking to Amazon.com and not an imposter? Notice the padlock icon? That's your browser telling you this connection is secure and verified. This trust problem is solved by digital certificates - cryptographic credentials that bind an identity to a public key. Let's see how they work! What is a Digital Certificate? A digital certificate is like a digital passport for websites and organizations. It's a file that contains: The key insight: The certificate binds the website's identity (like "www.amazon.com") to its public key . This prevents imposters from claiming to be Amazon! Certificate Authorities: The Trust Anchors But wait - who creates these certificates? How do we know they're legitimate? This is where Certificate Authorities (CAs) come in. Certificate Authority (CA) : A trusted organization that issues digital certificates after verifying the identity of the requester. Think of CAs like government agencies that issue passports. Just as you trust a passport because it's issued by a recognized government, you trust a certificate because it's issued by a recognized CA.

This is the written version of the interactive lesson above. See the full Cryptography course.