Who can a subscriber share their private signing key with?

A subscriber is responsible for the confidentiality and security of their private signing key within the Public Key Infrastructure (PKI). This key is a critical component used for creating digital signatures, ensuring authenticity and integrity of communications. Sharing this key compromises the security model of PKI because the private key is designed to remain confidential to the subscriber alone.

By keeping the private signing key private and personal, a subscriber ensures that only they can produce valid signatures associated with their identity. This is fundamental to maintaining trust in the PKI system. If anyone else were to obtain the private key, they could impersonate the subscriber, leading to potential security breaches, fraud, or misuse. Thus, the policy is clear: the private signing key must not be shared with anyone, which reinforces the integrity of the digital signature process and the overall security of the PKI.