Danika wonders about the mechanism that authenticates her identity when logging in from a new device. What is this a function of?

• A. Hashing
• B. Asymmetric encryption
• C. Symmetric encryption
• D. Password-based authentication

Answer: (B)

Public-key authentication uses an asymmetric key pair to prove you are who you say you are. When you log in from a new device, the server can issue a challenge, and your device signs that challenge with its private key. The server uses the corresponding public key to verify the signature. If it checks out, your identity is confirmed without sending a password over the network. The private key stays on your device, so the login proof travels as a cryptographic signature rather than a password, which makes it reliable across new devices.

Hashing is mainly for securely storing or comparing passwords and for data integrity, not for proving identity in a login flow. Symmetric encryption would require sharing a secret key between the device and server, which complicates management across many devices. Password-based authentication relies on something you know, which can be vulnerable if the password is compromised or phished.