Which of the following is a secret numeric password shared between a user and a system for
authenticating the user to the system?

A.
PIN

B.
Private key

C.
Key escrow

D.
Public key

Explanation:

A personal identification number (PIN) is a secret numeric password shared between a user and a
system for authenticating the user to the system.

Answer C is incorrect. Key escrow is an arrangement in which the keys needed to decrypt encrypted
data are held in escrow so that, under certain circumstances, an authorized third party may gain
access to those keys. These third parties may include businesses, who may want access to
employees’ private communications, or governments, who may wish to be able to view the contents
of encrypted communications.

Answer B is incorrect. In cryptography, a private or secret key is an encryption/decryption key
known only to the party or parties that exchange secret messages. In traditional secret key
cryptography, a key would be shared by the communicators so that each could encrypt and decrypt
messages.

Answer D is incorrect. A Public Key is known commonly to everybody. It is used to encrypt data.
Only specific users can decrypt it. Data encryption is used to encrypt data so that it can only be
decrypted with the corresponding private key owned by the public key owner. The public key is also
used to verify digital signatures. This signature is created by the associated private key.