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 OXAA. In the case of CTRmode, we use a (nonce || counter) arrangement in which the nonce is the left 5 bits of OXAA and the counter is a 3 bit counter that begins at 0. In all of theproblems given below, one character is one block. Each character of the plaintext should be regarded as its corresponding ASCII code.a) Encrypt the plaintext "blotto" using CTR mode. Please enter your answer in hex. (Please do **not** enter an 0x, as this has been done.)Oxb) Encrypt the plaintext "blind" using ECB mode. Please enter your answer in hex.Oxc) Encrypt the plaintext "rango" using CFB mode. Please enter your answer in hex.Oxd) Encrypt the plaintext "rind" using CBC mode. Please enter your answer in hex.Oxe) Encrypt the plaintext "pepper" using OFB mode. Please enter your answer in hex.Ox

We have to encrypt the given following plaintexts into the equivalent hexadecimal format using…

a) Encrypt the plaintext "blotto" using CT R mode. Please enter your answer in hex. (Please do *not** enter an Ox, as this has been done.) Ox b) Encrypt the plaintext "blind" using ECB mode. Please enter your answer in hex. Ox c) Encrypt the plaintext "rango" using CF B mode. Please enter your answer in hex. Ox d) Encrypt the plaintext "rind" using C BC mode. Please enter your answer in hex. Ox e) Encrypt the plaintext "pepper" using OF B mode. Please enter your answer in hex. Ох

a) Encrypt the plaintext "blotto" using CT R mode. Please enter your answer in hex. (Please do *not** enter an Ox, as this has been done.) Ox b) Encrypt the plaintext "blind" using ECB mode. Please enter your answer in hex. Ox c) Encrypt the plaintext "rango" using CF B mode. Please enter your answer in hex. Ox d) Encrypt the plaintext "rind" using C BC mode. Please enter your answer in hex. Ox e) Encrypt the plaintext "pepper" using OF B mode. Please enter your answer in hex. Ох

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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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.
Suppose we will use Advanced Encryption Standard (AES) to encrypt a block of plaintext andthe known round key for round 7 is:B5 8D BA D2 31 2B F5 60 7F 8D 29 2F EA D2 73 21Please calculate the first four words of the round key for round 8 by following the steps below:(1) What is the ‘temp’ value after RotWord? (2) What is the value after SubWord? (3) What is the value after XOR with Rcon? (4) What is the first word (i.e. the first 4 bytes) of the round key for round 8? (5) What is the third word (i.e. the third 4 bytes) of the round key for round 8?
Question: Using the simplified RC4 Algorithm of 8 bytes (rather than the full 256 bytes), find the final Keystream and Cipherpext of the following Input string: S-Array of length 8, [S0 S1 S2 S3 S4 S5 S6 S7] = [7 6 5 4 3 2 1 0] Key, K = [3 1 4 1 5] Plaintext, PT = [6 1 5 4] Hint: For the simplified stream generation, you can use this pseudocode (only up to the PT length): /* Initialization */ set i and j = 0 for i = i + 1 to length of PT j = j + S[i] mod 8 swap S[i], S[j] t = S[i] + S[j] mod 8 Keystream = S[t] end for
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.
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…
Consider the affine cipher f(p) = 3p+4 (mod 26), where p is the plaintext representation of the character under consideration. For example the plaintext of the letter A is 0, B is 1, C is 2, ... Z is 25. Use this cipher to encrypt the letters I, N, G, R (changing the numbers back to letters at the end.
Using the encryption and decryption methods, write a program called SDESMitm.java or sdesmitm.py that will carry out a meet-in-the-middle attack on 2SDES. This system encrypts a plaintext first with one key and then again with a different key. Please review the attack in the notes and the textbook. Recall that this is a known-plaintext attack. I will provide plaintext/ciphertext pairs. Based on those, you should be able to recover the two 9-bit keys. Write the program so that it can be run from the command line taking four parameters: plaintext 1 integer ciphertext 1 integer plaintext 2 integer ciphertext 2 integer Two pairs are needed because the first plaintext/ciphertext pair will let you create a short list of key pairs and the second plaintext/ciphertext pair will allow you to narrow that list down to one key pair. When run, the program should print the two keys. You can test your program on the plaintext/ciphertext pairs 0/247; 4095/2808. In my implemenation, the firat…
Assume that you have a suitable source of randomness which can produce at least 264264 random bits before it repeats. What is the easiest way to turn this into a stream cipher suitable for encrypting long streams of plaintext?
Suppose Data Encryption Standard (DES) is used to encrypt the following 64-bit block of plaintext: 6 3 F A C 0 D 0 3 4 D 9 F 7 9 3 Given the initial 64-bit key is: 1 C 5 8 7 F 1 C 1 3 9 2 4 F E F Expand R0 to get E[R0]
Suppose we will use Advanced Encryption Standard (AES) to encrypt a block of plaintext and the known round key for round 7 is: B5 8D BA D2 31 2B F5 60 7F 8D 29 2F EA D2 73 21 What is the third word (i.e. the third 4 bytes) of the round key for round 8?
The definition of a Shift Cipher can be expressed as follows:Def. Let x, y, k ∈ Z26 with the encryption operation as ek(x) ≡ x + k mod 26 and thedecryption operation as dk(y) ≡ y - k mod 26.Given the provided letter encoding, what would be the encoding of the plaintext word ATTACKafter applying a shift cipher with a k=17?
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?