What occurs when a subscriber shares their private signing key?

When a subscriber shares their private signing key, it causes a significant security risk. The private signing key is a critical component of asymmetric encryption used in digital signatures and ensuring the integrity of communications. When this key is shared, unauthorized individuals can use it to impersonate the subscriber, create false signatures, and potentially compromise sensitive information or systems. The core principle of PKI is that the private key must remain confidential and known only to its owner; this confidentiality is essential for maintaining trust in the digital signature infrastructure. Sharing the private signing key undermines this trust and the overall security of the PKI system, making it a major concern for all users of such systems.