During the process of encryption and decryption, what keys are shared?

Private keys are never shared - they are held exclusively by their owner and sharing them would completely compromise the security of the key pair.

User passwords are authentication credentials, not cryptographic keys used in the encryption and decryption process.

Asymmetric encryption uses a key pair where the public key is intentionally distributed to any party that needs to send encrypted data or verify a digital signature. Sharing the public key does not compromise security because data encrypted with it can only be decrypted by the corresponding private key. This open sharing of public keys is a foundational design principle of PKI systems.

Only public keys are shared; sharing private keys would defeat the entire purpose of asymmetric encryption and expose all protected communications.