Security guides
Practical guides to passkeys, WebAuthn deployment, RP IDs, app associations, and SSL/TLS certificate chains, with checklists and troubleshooting tools.
Articles in Security
SSL Certificate Chain Explained: Root, Intermediate and Leaf Certificates
Root, intermediate and leaf certificates, what each link does, and how to fix "unable to get local issuer certificate".
Passkeys Explained: How Passwordless Sign-In Works
A practical introduction to passkeys: public-key authentication, phishing resistance, synced credentials, recovery, and the deployment work behind the sign-in button.
Passkey Deployment Checklist: From Staging to Production
A release checklist that separates public configuration from backend verification and real-device testing, with concrete checks for web, Apple, and Android deployments.
WebAuthn RP ID and Related Origins: A Deployment Guide
Learn where RP IDs and browser origins differ, when related origins are needed, and how to debug cross-domain passkeys without broadening your trust boundary accidentally.
Passkey Deployment Checker: How to Read Your Report
A practical walkthrough of checker inputs, six check categories, five result statuses, and the follow-up tests a public configuration report cannot replace.
About this section
Many security errors come from configuration rather than attacks. A certificate can be valid and still be rejected because the server sends an incomplete chain, or because the certificate does not cover the hostname being requested.
These guides explain how TLS trust works in practice: how root, intermediate and leaf certificates link together, how clients validate them, and why the same site can load in a browser but fail from curl, a mobile app or an API client.
For passwordless authentication, start with passkeys explained, then follow the production deployment checklist. The RP ID and related origins guide covers domain boundaries, while the Passkey Deployment Checker guide explains public configuration findings and their limits.
Use the Passkey Deployment Checker to inspect HTTPS, RP ID compatibility, related origins, and selected app association files. A public configuration report does not replace registration, sign-in, or recovery tests.
To inspect a live host, use the SSL Certificate Checker. The Hash Generator is useful when you need to compare fingerprints or checksums.
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