A large backup file is encrypted with the same secret information shared in advance by the sender and receiver.
Which statement correctly describes this method?
Symmetric encryption uses the same key for encryption and decryption, so securely sharing the key is important.
Detailed explanation
Incorrect. A secret key must not be made public; anyone with it could decrypt the data.
Correct. The same key is used for encryption and decryption, making secure key exchange a challenge.
Incorrect. A public/private key pair belongs to asymmetric encryption.
Incorrect. The statement describes neither the key use nor the security model of symmetric encryption.
Try it yourself
An example you can run in a temporary verification environment.
printf '%s\n' 'same secret key encrypts and decrypts'Expected result
same secret key encrypts and decryptsKey points
- Same key
- Key sharing
- Large data
Notes
- Environment: 暗号方式の概念確認
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Host key
A server identity key used by SSH clients to detect a changed endpoint.
User key
A key pair used to authenticate a user to an SSH server.
Port forwarding
An SSH tunnel that carries traffic between a local, remote, or dynamic endpoint.