The second phase of Public Key Infrastructure (PKI) key/certificate life-cycle management is the initialization phase. PKI is a system that uses public key cryptography and digital certificates to provide authentication, confidentiality, integrity, and non-repudiation for electronic transactions. PKI key/certificate life-cycle management is the process of managing the creation, distribution, usage, storage, revocation, and expiration of keys and certificates in a PKI system. The key/certificate life-cycle management consists of six phases: pre-certification, initialization, certification, operational, suspension, and termination. The initialization phase is the second phase, where the key pair and the certificate request are generated by the end entity or the registration authority (RA). The initialization phase involves the following steps:

The end entity or the RA generates a key pair, consisting of a public key and a private key, using a secure and random method.

The end entity or the RA creates a certificate request, which contains the public key and other identity information of the end entity, such as the name, email, organization, etc.

The end entity or the RA submits the certificate request to the certification authority (CA), which is the trusted entity that issues and signs the certificates in the PKI system.

The end entity or the RA securely stores the private key and protects it from unauthorized access, loss, or compromise.

The other options are not the second phase of PKI key/certificate life-cycle management, but rather other phases. The implementation phase is not a phase of PKI key/certificate life-cycle management, but rather a phase of PKI system deployment, where the PKI components and policies are installed and configured. The cancellation phase is not a phase of PKI key/certificate life-cycle management, but rather a possible outcome of the termination phase, where the key pair and the certificate are permanently revoked and deleted. The issued phase is not a phase of PKI key/certificate life-cycle management, but rather a possible outcome of the certification phase, where the CA verifies and approves the certificate request and issues the certificate to the end entity or the RA.