The company should implement Security Assertion Markup Language (SAML) to integrate the vendor's security tool with their existing user directory. SAML is an open standard that allows identity providers (IdP) to pass authorization credentials to service providers (SP), enabling Single Sign-On (SSO). This allows the company to use its existing directory services for authentication, avoiding the need to manage a separate set of user credentials for the new tool.

Non-repudiation is the ability to prove that a message or document was sent or signed by a particular person, and that the person cannot deny sending or signing it. Non-repudiation can be achieved by using cryptographic techniques, such as hashing and digital signatures, that can verify the authenticity and integrity of the message or document. Non-repudiation can be useful for legal, financial, or contractual purposes, as it can provide evidence of the origin and content of the message or document.

From a practical standpoint, an administrator would use automation to compare all existing certificates with the revocation list, but potentially they could also script to OCSP per each certificate in the environment. Either option seem valid, but CRL seems the better option from enterprise scan perspective.