I need the solution quickly within 15 minutes Question 1:An IT system allows the users to access the system using passwords of lengths ranging from five toeight characters long with the following specifications: the length five characters can only be bitstring with three consecutive 1s; the length six passwords can be case independent alphabets or bits,but each password of this length must contain one alphabet; the length seven passwords can beACSII letters with “@" at the beginning or again "@" at the end of each password; and thepasswords of length eight can be only bit strings with at most three Os. Determine the total possiblepasswords are there as allowed by the IT system?

We will calculate the number of possible strings compelling with the IT system's rules. Below are…

Answered: An IT system allows the users to access…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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You are placing an order with an online retailer. To complete a purchase, your web browser sends a single encrypted, MAC-authenticated message to the web site, consisting only of the following information: a) your credit card information, b) the item number and quantity being ordered. a. Write a formula using the function symbol MAC(…) to indicate what is being authenticated. You may choose any reasonable variable names for the data items. b. Say an adversary is sitting between you and the retailer, with the ability to intercept traffic and send messages. Assume the authentication is not vulnerable to length extension. Describe a cryptographic attack the adversary could carry out to “max out” your credit card. What type of attack is this? c. What could the retailer do to prevent this attack, simply by changing what data is sent in that single encrypted, authenticated message? Write a new MAC() formula to show the new construction.
A large number of consecutive IP address are available starting at 192.32.0.0. Suppose that three organizations, A, B and C, request a000 (a thousand), b000 (b thousand) and c000 (c thousand) addresses, respectively, and in that order. For each of these, give the first IP address assigned, the last IP address assigned, and the mask in the w.x.y.z/s notation. The student should write details of calculations. (Note: a, b and c are defined as your last three numbers of student ID. For example, if your student ID is 18290102 then a=1, b=0 and c=2. So, organization A requests 1000, B requests 0 and C requests 2000 addresses). MY NUMBER:16290025
Prior to the introduction of IEEE 802.11i, the security scheme for IEEE 802.11 was Wired Equivalent Privacy (WEP). WEP assumed all devices in the network share a secret key. The purpose of the authentication scenario is for the STA to prove that it possesses the secret key. Authentication proceeds as shown in Figure 24.13 . The STA sends a message to the AP requesting authentication. The AP issues a challenge, which is a sequence of 128 random bytes, sent as plaintext. The STA encrypts the challenge with the shared key and returns it to the AP. The AP decrypts the incoming value and compares it to the challenge that it sent. If there is a match, the AP confirms that authentication has succeeded.
A school is upgrading its website and will require students to create a password to access theirmarks online. In order to create secure passwords, students will be required to meet certainconditions.a. Determine the total number of possible 4-character passwords that can be created using eachof the following requirements the pattern letter – letter – number – number, using the 26 letters of the alphabet, and thedigits 0 to 9, where letters and digits can be repeated
A school is upgrading its website and will require students to create a password to access theirmarks online. In order to create secure passwords, students will be required to meet certainconditions.a. Determine the total number of possible 4-character passwords that can be created using eachof the following requirements: the digits 0 to 9, where the first digit must be even and last digit must be odd, and wheredigits can be repeated
In this problem we explore the relationship between password length and cryptographic security. Suppose a password consists of 6 ASCII characters. You can review the ASCII characters here.. Exactly 2^7 = 128 of these codes are for printable characters; we will assume every character in the password is printable. What is the size of the keyspace that consists of passwords of this form? What is the equivalent key length in bits? Assuming that you could check one password every 10^-8 seconds, what is the worst case running time for cracking this password by brute force search (in days)? Now assume that the user used only 31 characters from the keyboard. What is the key length in bits in this case? How many days, in the worst case, would it take to break this weaker password? You can't round to the nearest day here -- be as exact as possible. Supposing you used only 31 characters, how long is the shortest password that achieves 84 bits of security?
A local area network requires eight characters for a password. The first character must be a letter, but the remaining seven characters can either be a letter or a digit (0 through 9). Lower & uppercase letters are considered the same. A. How many passwords are possible for the local area network? B. In 1 second, a 3-GHz computer processor can generate about 3 million passwords. How long would it take such a processor to generate all the passwords above? In seconds.
In this problem we explore the relationship between password length and cryptographic security. Suppose a password consists of 77 ASCII characters. You can review the ASCII characters here.. Exactly 27=12827=128 of these codes are for printable characters; we will assume every character in the password is printable. What is the size of the keyspace that consists of passwords of this form?What is the equivalent key length in bits? Assuming that you could check one password every 10−810−8 seconds, what is the worst case running time for cracking this password by brute force search (in days)? Now assume that the user used only 3131 characters from the keyboard. What is the key length in bits in this case? How many days, in the worst case, would it take to break this weaker password? You can't round to the nearest day here -- be as exact as possible. Supposing you used only 3131 characters, how long is the shortest password that achieves 252252 bits of security?
You are given the following parameters in RSA cryptosystem: p = 11, q = 13, e = 13 a) Find the integer d. b) List down the public key and private key. You need to encrypt the plaintext message, M = OF. c) Convert this message to value according to ASCII table. To encrypt this message, you can either combine the value, or separate it into the blocks of 2 digits (Hint: it must satisfy the condition M < n). d) Encrypt and decrypt the message OF. e) If the decimal value (not character) of ciphertext is 188267, decrypt this value and convert it to an appropriate message according to the ASCII table.
In this problem we explore the relationship between password length and cryptographic security. Suppose a password consists of 1212 ASCII characters. You can review the ASCII characters here.. There are exactly 27=12827=128 ASCII characters; we will assume every character in the password is ASCII (non-printing characters are allowed). What is the size of the keyspace that consists of passwords of this form? ___What is the equivalent key length in bits? ___ Assuming that you could check one password every 10−710−7 seconds, what is the worst case running time for cracking this password by brute force search (in days)? ___ Now assume that the user used only 2828 characters from the keyboard. What is the key length in bits in this case? ___ How many days, in the worst case, would it take to break this weaker password? You can't round to the nearest day here -- be as exact as possible. ___ Supposing you used only 2828 characters, how long is the shortest password that achieves 249249 bits…
Assume you are using any correct plaintext padding method, such as those described in lecture, with a 128-bit (16-byte) block cipher. If you are sending a message that is 184 bytes long, how many padding bytes would you need to add? Justify your answer. For the remaining questions, consider a 4-bit block cipher, described in hexadecimal by the following table: Plaintext Ciphertext Plaintext Ciphertext 0 a 8 e 1 c 9 d 2 f a 0 3 6 b 7 4 3 c 5 5 8 d b 6 4 e 9 7 2 f 1 You can think of this as a simple substitution cipher for hexadecimal digits. There is no “key” other than the table itself.
OBX Cart Rentals has created a website for customer access. They are trying todetermine a reasonably secure number of available passwords. They have decided toallow upper case letters, lower case letters, digits (0 – 9), and the three pecialcharacters: $, ! ?. Find the number of possible 6 character passwords given each of theconditions (Note: you MUST simplify completely.)a. The password must begin with a letter (either upper or lower case)i. repetitions permittedii. repetitions not permittedb. The password must begin with a letter and end with a special character ($, !, ?):i. repetitions permittedii. repetitions not permitted

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