What should Yariv do after accidentally exposing his private key to others?

After accidentally exposing his private key to others, Yariv should create a new keypair and notify others. This action is crucial because the private key is essential for ensuring secure communication and data integrity. If the private key has been exposed, anyone who has access to it can decrypt messages intended for Yariv, impersonate him, or alter communications, which compromises security significantly.

Creating a new keypair mitigates the risk associated with the exposed key, as it will generate a fresh, secure public-private key pair. After generating the new keypair, notifying others who relied on the old key ensures that they can update their records and use the new public key for secure communications going forward. This proactive step is critical in maintaining the confidentiality and integrity of data exchanges.

Other choices do not adequately address the severity of the incident. Ignoring the exposure can lead to potential breaches, and changing email settings might make the email safer but does not fix the core problem of the exposed key. Removing the email from the server does not prevent unauthorized access to the old key or secure communications in the future.