Certificate Validation plays a vital role to protect your secure connection from invalid certificates. It can validate the digital signature of the certificate using the public key of the CA (which is readily available to anyone). Once the signature is validated, the certificate contents are ready to be trusted.
The first step in validating a certificate is to check that the certificate has been issued by a trusted certificate authority. This can be identified by the issuer field specified in certificate which lists the name of a certificate authority which has vouched for the validity of the certificate. The next step of validating a certificate is to verify the certificate’s integrity. Final step is to ensure that the certificate has not expired. This is done by verifying the validity dates included in the certificate.