What solution should be implemented for cost-effective multi-factor authentication in a company utilizing PKI?

Implementing individual private/public key pairs for each user is a strong cost-effective solution for multi-factor authentication, especially in a company utilizing Public Key Infrastructure (PKI). This method leverages the existing PKI framework to provide secure identity verification through cryptographic means.

In a PKI system, users possess a unique private key that is securely stored on their devices, while the corresponding public key is available on the central server. This two-key system enables strong authentication, as the private key is required to sign transactions or authenticate to services, while the public key validates the identity of the signer. Using these key pairs enhances security by ensuring that even if one key is compromised, the other remains protected, adding a layer of assurance in the authentication process.

This approach is also cost-effective because it eliminates the need for physical tokens or biometric systems, which can involve higher costs for deployment, maintenance, and user training. Instead, by utilizing existing infrastructure and focusing on software-based mechanisms, the company can ensure robust authentication while minimizing additional costs.

The other options do not align as closely with the existing PKI framework or have higher implementation costs and complexity. For instance, hardware tokens require significant upfront investment and ongoing management, while biometric authentication necessitates specialized technology and