b. Now consider we want to reduce this number by generating a smaller pool of prime numbers and making combinations of two of these primes (for each user we pick up a new pair). How is security of RSA cryptosystem affected?

b. Now consider we want to reduce this number by generating a smaller pool of prime numbers and making combinations of two of these primes (for each user we pick up a new pair). How is security of RSA cryptosystem affected?

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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d. What is the relevance of Euler's theorem, awln) = 1 mod n, to the RSA cryptosystem? e. Use Euler's theorem to work out 2123458 mod 21. You should not need a calculator.
Note: The notation from this problem is from Understanding Cryptography by Paar and Pelzi. Consider the LFSR represented by the polynomial x¹ + x³ +x+1 What are the tap bits of the LFSR? Please enter your answer as unspaced binary digits (e.g. 010101 to represent p = 0, P4 = 1, P3 = 0, P2 = 1, P₁ = 0, Po = 1).
The hacker group Desdeia tries to break our old weak cipher which we used for the communication with the Duchess of Ligovia. It's generally known that an actual breaking of the cipher needs the reviewing a huge amount of variants which probably lasts a couple of months. Additionally we know that the reviewing of different variants needs always the same server resource. Using our intelligence sources we tried to get some information about the actual progress of breaking, but we got only some fragments: • The hacker group Desdeia uses for breaking their powerful four-core server which resources are fully dedicated to breaking process. . The actual breaking process began exactly at noon, but we don't know, on which day. . By the noon of 2nd of April, already 648,467,673 variants were successfully reviewed. Exactly at this noon, when the breaking process was already lasted for 19 days, it was attempted to double the server speed. The doubling itself was failed, but instead of it there was…
Show all of the steps needed to encrypt and decrypt the ASCII message “YES” without a modular arithmetic calculator in an RSA cipher with public key (143, 7).
i need the answer quickly
For a block cipher with encryption Ek() and decryption DK(), the equation for the CBC mode of operation is: Cj = EK(Pj e Cj-1). What is the equation for decrypting C?
Note: The notation from this problem is from Understanding Cryptography by Paar and Pelzi. Suppose you have an LFSR with 6 state bits. The first 12 bits of output produced by this LFSR are 101011100010 = 80818283848586878889810811- The first bit produced is the leftmost bit and the bit most recently produced is the rightmost bit. a) What is the initial state of the LFSR? Please enter your answer as unspaced binary digits (e.g. 010101 to represent 85 = 0, $4 = 1, 83 = 0, 82 = 1, 81 = 0, 80 = 1). b) What are the tap bits of the LFSR? Please enter your answer as unspaced binary digits (e.g. 010101 to represent p = 0, P₁ = 1, P3 = 0, P2 = 1, P₁ = 0, Po = 1).
Consider a very simple symmetric block encryption algorithm in which 32-bits blocks of plaintext are encrypted using a 64-bit key. Encryption is defined as C = (PK₁) K₁ where C = ciphertext, K = secret key, Ko = leftmost 64 bits of K, K₁ = rightmost 64 bits of K,+ = bitwise exclusive OR, and is addition mod 264. a. Show the decryption equation. That is, show the equation for P as a function of C, Ko, and K₁. b. Suppose and adversary has access to two sets of plaintexts and their correspond- ing ciphertexts and wishes to determine K. We have the two equations: C = (PK) K₁; C = (PK) K₁ First, derive an equation in one unknown (e.g., Ko). Is it possible to proceed fur- ther to solve for Ko?
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Note: The notation from this problem is from Understanding Cryptography by Paar and Pelzl. We conduct a known-plaintext attack against an LFSR. Through trial and error we have determined that the number of states is m = 4. The plaintext given by 01100101 —D ХоXјX2XҙX4X5X6X7 when encrypted by the LFSR produced the ciphertext 10010100 — Уo У1 У2 Уз Уз У5 У6 Ут- What are the tap bits of the LFSR? Please enter your answer as unspaced binary digits (e.g. 0101 to represent P3 = 0, p2 = 1, Pi = 0, po = 1).
In the Elgamal encryption scheme, Bob's public key is fixed, but Alice uses a fresh random i e {2,...,p – 2}, and hence a fresh random kg, whenever she wants to send Bob a message. What happens if Alice uses the same i for ecrypting multiple messages? Can Trudy recover any meaningful information from the ciphertexts?
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?