In asymmetric encryption, how is a message encrypted for the recipient?

In asymmetric encryption, a message is encrypted using the recipient's public key to ensure that only the intended recipient can decrypt and read the message. This method leverages the principles of asymmetric cryptography, where each participant has a pair of keys: a private key that is kept secret and a public key that is shared openly.

When the sender encrypts a message with the recipient's public key, it ensures that even if the encrypted message is intercepted, it cannot be decrypted without access to the corresponding private key, which only the recipient possesses. This process provides a high level of security and confidentiality, as it allows for secure communication over an insecure channel.

In contrast, using the sender's private key would not encrypt the message in a way that protects its confidentiality; instead, it would allow anyone with access to the public key to decrypt the message. Employing a shared secret key pertains to symmetric encryption, where both sender and recipient use the same key. Lastly, using a random key does not align with the principles of asymmetric encryption and does not ensure that only the recipient can decrypt the message.