Why Do Certificates Expire?
It's not a business model. Short lifespans are a deliberate security control.
50 guides covering the foundations: what SSL/TLS is, how the handshake works, the cryptography underneath, and every certificate type and field you'll run into.
It's not a business model. Short lifespans are a deliberate security control.
The site doesn't go down. It goes to a full-page warning that most visitors will not click through.
The field that quietly replaced the old "Common Name" as the thing browsers actually check.
The trick that lets one IP address serve HTTPS for hundreds of unrelated domains.
A property that protects past conversations even if your private key leaks tomorrow.
A stricter trust model used mostly in mobile apps — and a common cause of mysterious connection failures.
Every publicly trusted certificate issued today is logged, permanently, in public — including for domains you own.
A checklist your browser runs through in milliseconds, every single time you load a page.
The file most "not trusted on my phone but not my laptop" issues trace back to.
One insecure image can be enough to downgrade an entire page's security status.