How is the public key distributed in an orderly, controlled fashion so that the users can be sure of the sender's identity?

A hash value is used for data integrity verification, ensuring data has not been tampered with, but it does not establish the authenticity of a public key's owner.

A private key must remain confidential and is never distributed, as it is used by the owner to decrypt messages or create digital signatures.

A digital signature uses a private key to prove the integrity and authenticity of a message or document, but it is the result of using a key, not the mechanism for securely distributing the public key itself.

A digital certificate is a cryptographically signed electronic document that binds a public key with the identity of the certificate owner. When a public key is distributed within a digital certificate issued by a trusted Certificate Authority (CA), users can verify the CA's signature and trust that the public key belongs to the claimed sender.