This error message typically arises when a system attempting a secure connection cannot verify the authenticity of the server’s digital certificate. A digital certificate acts like an online identification card, confirming the server’s identity. The verification process involves checking this certificate against a chain of trusted authorities. A break in this chain, an expired certificate, or a certificate issued by an untrusted authority can lead to connection failure. For example, a user’s browser might display this error when trying to access a website with an invalid or expired SSL certificate.
Secure communication and data integrity rely heavily on trusted certificate authorities. Preventing unauthorized access and man-in-the-middle attacks is a primary function of this system. Historically, the development of robust certificate authorities and protocols has been crucial for the growth of e-commerce and secure online communication. Without these safeguards, sensitive information transmitted online would be vulnerable to interception and manipulation.