Question

1. If you use a randomly chosen 4 character password (comprising of all the lowercase, uppercase letters and digits 0 to 9), say “Xp9m” how many maximum guesses are required by a computer to guess this password? Compare the strength of this password with an 8 character password instead (say “Cm8Rz0pQ”) ? Show the simple math that is underlying the calculation.

Do you agree with the statement “ An 8 letter password is around two times more secure than a 4 letter password.” ?

Answer 1

Q-> If you use a randomly chosen 4 character password (comprising of all the lowercase, uppercase letters and digits 0 to 9), say “Xp9m” ,

how many maximum guesses are required by a computer to guess this password?

number of choices for single character: 26 uppercase + 26 lowercase + 10 digits = 62

=> maximum guesses required to guess 4 character password = 62 * 62 * 62 * 62 = 14776336 , ie in order of 10 ^ 7

.

Compare the strength of this password with an 8 character password instead (say “Cm8Rz0pQ”) ?

number of choices for single character: 26 uppercase + 26 lowercase + 10 digits = 62

=> maximum guesses required to guess 8 character password = 62 * 62 * 62 * 62 * 62 * 62 * 62 * 62 = 218340105584896 , ie in order of 10 ^ 14

.

Do you agree with the statement “ An 8 letter password is around two times more secure than a 4 letter password.” ?

Yes, this statement is true, infact 8 letter password is much more secure than 4 letter password, A computer who guesses 4 character password in 1 second will need

10 ^ 7 seconds to guess 8 character password.