Requirements for a complex password system include using a value, implementing strong encryption, requiring periodic password changes, and generally implementing a system where guessing a password or its hash is very difficult.
a. hex
b. salt
c. zero
d. known

The answer is B

A salt is an extra layer of security used when storing sensitive data. It is a random string that is added to the input data before being hashed.

Even though a hash function is already asymmetrical (cannot be decrypted), if multiple users have the same password, their hashed passwords would still be the same. Therefore if there were to be a data breach, a hacker could recognize duplicate hash values and guess what the passwords might be by trying common passwords such as "password" or "12345".

When a salt is added, the hash value of two identical passwords will be different.