Q4:- A fast computer is used to break a ciphertext (A) using columnar transposition cipher that needs 150 attempts, the speed of processor is 4 MIPS (million instructions per second), and each attempt needs 5 instructions. Another computer of speed 3 MIPS is used to break ciphertext (B) using Caesar Cipher that needs 110 attempts, and each attempt needs 4 instructions for ciphertext (B). Determine which ciphertext will be broken first (consider the worst case, i.e. the last attempt is the successful one), write your answer in details?

Q4:- A fast computer is used to break a ciphertext (A) using columnar transposition cipher that needs 150 attempts, the speed of processor is 4 MIPS (million instructions per second), and each attempt needs 5 instructions. Another computer of speed 3 MIPS is used to break ciphertext (B) using Caesar Cipher that needs 110 attempts, and each attempt needs 4 instructions for ciphertext (B). Determine which ciphertext will be broken first (consider the worst case, i.e. the last attempt is the successful one), write your answer in details?

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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Cryptography problem mathematics Suppose Alice and Bob are using a cryptosystem with a 128-bit key, so there are 2128possible keys. Eve is trying a brute-force attack on the system.(a) Suppose it takes 1 day for Eve to try 264 possible keys. At this rate, how long willit take for Eve to try all 2128 keys? (b) Suppose Alice waits 10 years and then buys a computer that is 100 times fasterthan the one she now owns. Will she finish trying all 2128 keys before or after whatshe does in part (a)?
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. 1) 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. 2) 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. I need an octave code for the first part of this question, that i can just copy and paste. In addition, to an explanation of the steps done to…
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.
Let the input size of a block cipher be 16 bits and the block cipher is used in the electronic code book (ECB) mode of operation. Suppose we have the following plaintext where all blocks are encrypted using the same key: (02 34 67 88 02 34 44 AB 67 88 B0 3F)hex i) Let say the encrypted important file is stored in this scheme and each data record has a size of 16 bits. The records are not related to one another. Is ECB mode still appropriate in this scenario? Please state your reason.
Computer Science Assume we use transposition cipher to encrypt the data, and the original message is stored in a 8 by 5 matrix (8 rows and 5 columns). If the ciphertext is shown below, what is the original plaintext?WMHPSCATEEEUCELELTCTIASLOTMRNCA
Using public key cryptography, X adds a digital signature s to message M, encrypts <M, s>, and sends it to Y, where it is decrypted. Which one of the following sequences of keys is used for the operations? A) Encryption: X's private key followed by Y's private key; Decryption: X's public key followed by Y's public key B) Encryption: X's private key followed by Y's public key; Decryption: X's public key followed by Y's private key C) Encryption: X's public key followed by Y's private key; Decryption: Y's public key followed by X's private key D) Encryption: X's private key followed by Y's public key; Decryption: Y's private key followed by X's public key
8. A security system is used to encrypt the password of a cryptocurrency wallet (crypto wallet) and generate 10 different codes that the owner of the wallet can copy on 10 papers that he will hide with great care. So if a thief finds 1 of these hidden papers, he will not be able to unlock the wallet. Indeed it would be necessary to have at least 6 (any 6) codes to reconstitute the secret passphrase and unlock the wallet. How is it possible ?
This question concerns block cipher modes. We will use a simple affine cipher, which can be expressed in C as follows. char cipher(unsigned char block, char key){ return (key+11*block)%256;} Note that the block size is 8 bits, which is one byte (and one ASCII character). We will work with the fixed key 0x08. We now encrypt various plaintexts using modes for this cipher. In every case in which the mode requires an IV, the IV will be 0xAA. In the case of CTR mode, we use a (nonce || counter) arrangement in which the nonce is the left 5 bits of 0xAA and the counter is a 3 bit counter that begins at 0. In all of the problems given below, one character is one block. Each character of the plaintext should be regarded as its corresponding ASCII code. a) Encrypt the plaintext "?????" using ??? mode. Please enter your answer in hex. (Please do **not** enter an 0x, as this has been done.)0x= * Can you please answer this question // input answer next to the "=" sign.
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.
Let k=( 4 1 3 2) be the encryption and key k = (2 4 3 1) be the decryption key used in a transposition cipher. Show all the steps to decrypt the following ciphertext using the keyed approach: “XYSEESRU”
Problems are on this Textbook: Stallings, W. (2019). Cryptography and Network Security (8/E). Pearson Publishing. ISBN: 978-0-13576-403-9 7.10 In discussing the CTR mode, it was mentioned that if any plaintext blocks that is encrypted data using a given counter value is known, then the output of the encryption function can be determined easily from the associated cipher text block. SHow the calculation.
Given the RSA public key (3,70747) and private key (46811,70747). a. Encrypt the letter ‘z’ using its ASCII value and implement in python. b. Decrypt the result from the subtask above and generate the original text and implement in python. c. Encrypt the word ‘Cyber’ two characters at a time padding with a space and implement in python. d. Decrypt the following three blocks 14520 66071 27623. The blocks are the encryption of a five-letter word, encrypted two characters at a time and padded with a space. Recover the word and implement in python. d. The blocks are the encryption of a five letter word, encrypted two characters at a time and padded with a space. Recover the word and implement in python. e. Determine the maximum block size, in bits, that this modulus can encrypt and decrypt.