A secure connection requires a verified identity. When a web browser attempts to establish a secure connection using HTTPS, the server presents a digital certificate. This certificate contains information about the server’s identity, including a subject name. The browser then checks if this subject name precisely matches the hostname the user intended to visit. If the certificate presents alternative subject names, such as Subject Alternative Names (SANs), the browser also checks for a match amongst those. When neither the primary subject name nor any SAN matches the intended hostname, the connection is rejected to prevent potential security risks. This mismatch can arise due to configuration errors on the server or attempts to impersonate a legitimate website.
Accurate certificate subject name matching is crucial for ensuring secure communication and preventing man-in-the-middle attacks. Without this verification, attackers could present fraudulent certificates, intercepting sensitive data like passwords and financial information. The increasing reliance on secure online transactions makes this verification process a fundamental component of internet security. Early implementations of secure communication protocols did not always enforce strict name matching, leading to vulnerabilities. The evolution of security best practices and browser implementations now prioritizes robust certificate validation, significantly improving online safety.
