The question is incomplete. The complete question is :
Holly the Hacker has a list of 100,000 common passwords. She wants to use this list to break into UNIX-like systems that use a password file with lines consisting of:
The user's ID in plaintext.
10 bits of randomly chosen "salt," in plaintext.
The user's password, concatenated with the salt, and then encrypted.
There are very many such systems around the world, and Holly plans to steal the password files from as many as she can. The average system has 50 users in its password file.
Holly wants to create a master list of the encrypted versions of all the 100,000 passwords on her list, encrypted with all possible salt values. To create this master list, approximately how many encryptions of a password-concatenated-with-salt would Holly have to perform?
A. 2 million
B. 5 million
C. 100 million
D. 1 million
Solution :
It is given that the hacker, Holly wants break into the UNIX-like systems using 100,000 common passwords that she has on her list. The system has at an average of 50 users in the password files.
Therefore, to create a master list, Holly have to perform about 50 x 100,000 = 5,000,000 encryptions for the password concatenated-with-salt.
Thus the correct option is option (B). 5 million
