Consider the collection of passwords of length 8, where each character is a lower case letter....
Assume passwords are 10 characters long, and each character is either a lower case letter, upper case letter, or digit 0, . . . , 9. (a) How many possible passwords are there? (b) How many passwords are there with at least one upper case letter, and also never repeat a character? (c) How many passwords are the same written forwards and backwards?
If passwords may contain lower case letters and digits, how many 6-character passwords start with the lower case letter 'a' or ends with the number '3'? Answer:
3. A computer system uses passwords that contain exactly eight characters, and each character is one of the 26 lowercase letter (a -z) or 26 uppercase letters (A - Z) or 10 integers (0-9). Let Ω denote the set of all possible passwords. Suppose that all passwords in Ω are equally likely. Determine the probability for each of the following: (a) Password contains all lowercase letters given that it contains only letters (b) Password contains at least 1 uppercase letter...
Cryptology 1.4. We now consider the relation between passwords and key size. For this purpose we consider a cryptosystem where the user enters a key in the form of a password. 1. Assume a password consisting of 8 letters, where each letter is encoded by the ASCII scheme (7 bits per character, i.e., 128 possible characters). What is the size of the key space which can be constructed by such passwords? 2. What is the corresponding key length in bits?...
Consider passwords of length 8 using symbols from the set of lower case letters: {a, b, c, ..., z}. (a) How many such passwords use the letter p exactly two times and the letter q exactly two times? To illustrate, both akpqbqop and quaqpoop satisfy this condition. Include a brief indication of your strategy. (b) How many such passwords use the letter p exactly once and the letter q exactly once and also have letters arranged so the p is...
A computer system uses passwords that contain exactly 4 characters, and each character is 1 of the 3 lowercase letters (a, b, c) or 3 upper case letters (A, B, C) or the 5 odd digits (1, 3, 5, 7, 9). Let Ω denote the set of all possible passwords, and let A and B denote the events that consist of passwords with only letters or only integers, respectively. Determine the probability that a password contains only numbers given that...
Q - Which is larger, the number of four-character passwords where each character is adigit from 1 to 8, or the number of eight-character passwords where each characteris a letter from A to D.
A hacker has programmed their computer to generate, uniformly at random, an eight-character password, with each character being either one of 26 lower-case letters (a-z), one of 26 upper-case letters (A-Z) or one of 10 integers (0-9). The hacker wants to infiltrate a website that has 2 million users. Assume, for simplicity, that each user is required to use a unique password. i. What is the expected number of attempts before the hacker successfully generates a user password? ii. What...
Write Java program: • Is at least 8 characters long • Contains at least 1 lower letter character • Contains at least 1 upper letter character • Contains at least 1 numeric digit • Contains at least 1 special character from the set: !@#$%^&* • Does not contain the word “and” or the word “the” Prompts the user for a password, including the requirements above in your output. Output a string that states valid or invalid. If invalid, state which...
A computer system uses passwords that contain exactly 3 characters, and each character is one of the 26 lowercase letters (a-z) or 26 uppercase letters (A-Z) or 10 integers (0-9). Let Ω denote the set of all possible passwords, and let and denote the events that consist of passwords with only letters or only integers, respectively Suppose that all passwords in 2 are equally likely. Determine the following probabilities. Round your answers to three decimal places (e.g. 98.765). (c) The...