Two users need to securely share encrypted files via email. Company policy prohibits users from sharing credentials or exchanging encryption keys. Which of the following can be implemented to enable…

Key escrow involves storing copies of encryption keys with a third party for recovery purposes, which does not solve the problem of securely exchanging encrypted files without sharing keys between the two users.

Digital signatures provide authentication and non-repudiation by verifying the identity of the sender, but they do not encrypt the content of the file or enable secure encrypted file sharing without key exchange.

PKI uses asymmetric cryptography where each user has a public/private key pair; the sender encrypts the file using the recipient's publicly available public key, and only the recipient can decrypt it with their private key, meaning no credentials or private keys ever need to be shared between users.

Hashing is a one-way function used to verify data integrity (e.g., checksums), not to encrypt or decrypt data, so it cannot be used to share encrypted files between users.