You are to encrypt a ciphertext using the permutation p : {0,1}4 → {0,1}4 defined as p(x) = ~x, ie, toggle each bit (O to 1 and 1 to 0). If you need an IV use 1010. If you need a nonce use 01. If the mode uses padding to handle arbitrary plaintext lengths, add 10* padding. If you need a counter, begin at 1. Encrypt the ciphertext 1110 1110 111 using ECB mode. Write four bits per box, with the final box possibly having fewer bits. Encrypt the ciphertext 1110 1110 111 using CBC mode. Write four bits per box, with the final box possibly having fewer bits. Encrypt the ciphertext 1110 1110 111 using CTR mode. Write four bits per box, with the final box possibly having fewer bits.

You are to encrypt a ciphertext using the permutation p : {0,1}4 → {0,1}4 defined as p(x) = ~x, ie, toggle each bit (O to 1 and 1 to 0). If you need an IV use 1010. If you need a nonce use 01. If the mode uses padding to handle arbitrary plaintext lengths, add 10* padding. If you need a counter, begin at 1. Encrypt the ciphertext 1110 1110 111 using ECB mode. Write four bits per box, with the final box possibly having fewer bits. Encrypt the ciphertext 1110 1110 111 using CBC mode. Write four bits per box, with the final box possibly having fewer bits. Encrypt the ciphertext 1110 1110 111 using CTR mode. Write four bits per box, with the final box possibly having fewer bits.

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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Using C programming language: A Transposition Cipher A very simple transposition cipher encrypt(S, N) can be described by the following rules: If the length of S is 1 or 2, then encrypt(S, N) is S. If S is a string of N characters s1 s2 s3... sN and k = N/2, then encrypt(S)= encrypt(sk sk−1... s2 s1 ,K)+ encrypt(sN sN−1... sk+1 ,N - K) where + indicates string concatenation. For example, encrypt("Ok", 2) = "Ok" and encrypt("12345678", 8) = "34127856". Write a program to implement this cipher. The input is a file that is guaranteed to have less then 2048 characters. Code structure might look like this: #define MAX_SIZE 2048char text_buffer[MAX_SIZE];int main(){ // read file into text_buffer encrypt(text_buffer, n); // print out text_buffer return 0;}
There are other modes of block cipher besides the ones (OFB,CFB,CTR). One of these modes is named Plaintext Block Chaining (PBC) Mode. On the encryption side, the following is executed to obtain the nth ciphertext: Cn := Ek(Mn)XOR Mn-1. Suppose that we need to encrypt M1; : : : ;M5 using the PBC mode. Show the explicit formulas to obtain C1; : : : ;C5. What do you need to use for M0? Also, show the steps on the decryption side to obtain M1; : : : ;M5.
In an RSA system, the public key (n,e) of a given user is (323, 11). 1. What is the value of the exponent in the private key (n, d), of this user? 2. Suppose you want to send this user the message m = 45, write down the expression to generate the ciphertext for this message. 3. Suppose that your ciphertext, c, is 5, write down the expression to generate the plaintext matching this ciphertext. 4. Can you encrypt the message m=322 with this public key? O a. Yes O b. No
Encrypt the 12-bit plaintext 101010100111 using Simplified B-DES and the 9-bit key K = 010001111. This is a non-computer problem and you need to show all the steps of the encryption process
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 a special case of a permutation cipher, we take a message, M, and write its letters in an s× t table, in a row-major fashion, and then let the ciphertext be a column-major listing of the entries in the table. For example, to encrypt the message ATTACKATDAWN, using a 3 × 4 table, we would write the message as ATTA CKAT DAWN and then write down the ciphertext as ACDTKATAWATN. The secret key in this cryptosystem is the pair (s, t). How is decryption done in this cryptosystem? Also, how hard would it be to attack this cryptosystem using a ciphertext-only attack?
Write using TCL commands (Cryptography) Write an invert procedure, that outputs the inverse of a permutation; for example, [invert {3 2 5 1 4}] should return {4 2 1 5 3}.
A symmetric block encryption algorithm is shown below. 16-bit blocks of plaintext P are encrypted using a 32-bit key. Encryption is defined as: C = (P EX_OR Ko) + K1 C is the ciphertext, K is the secret key, Ko is the leftmost 16 bits of K, K1 is the rightmost 16 bits of K, EX_OR is bitwise exclusive OR, and + is binary addition. a. The ciphertext C must be the same size as the plaintext P, that is, it must not be larger than 16 bits. How can this be achieved? b. Show the decryption equation. How will the encrypted message be decrypted?
Encrypt the word WEST using p=53 and q=71. Choose e=3. (Map A - Z to 126 and perform the encryption one letter at a time.)
In XOR Cipher, encoding is done by an XOR operation on two given strings. If the strings are of different lengths then the output should be the length of the shorter string. Cut the length of the longer string to the same size as the smaller string before XOR operation. Given two strings of msg1 and msg2, return the encoded message. Examples xor_cipher ("11", "22") "33" # 11 XOR 22 = 33 RUBY xor_cipher ("1020304", "403201") xor_cipher ("c611d9bdd9de38b9eb", "23a0745505d4d25494") "e5b1ade8dc0aeaed7f" "501231"
Affine Cipher is an example of a Monoalphabetic substitution cipher. The encryption process is substantially mathematical done by using the following formula: C = (P ∗ ?1 + ?2) mod 26. Where k1, k2 are two integers representing the key (selected randomly), C is the ciphertext value, and P is the plaintext value. Where C and P integers with values between 0 and 25. Write an Octave programme to implement this system, run your programme using the Plaintext: “the quick brown fox jumped over the lazy dog”. Show the obtained ciphertext with the selected values of the keys k1 & k2. Given that the plaintext “s” mapped to ciphertext “W”, plaintext “x” mapped to ciphertext “Z” when encrypted with Affine Cipher. Determine, mathematically, the values for the two keys K1 and K2.
] You receive a message that was encrypted using the RSA system with public key (43, 143), where 43 is the public exponent. A message encrypted using this cryptosystem was captured by an enemy and consisted of the following numbers: 6 82 132 115. Can you decipher what was the original message? (Hint: As a first step, you need to find p and q.)