The state of a feedback shift register of length L is a bit string of length L. true / O false Asynchronous stream ciphers provide enhanced security over synchronous | O true / O false ones by generating key streams at random. There exists a primitive polynomial of degree 128 over Z2. true / O false DES and AES are examples of block ciphers. true / O false

The state of a feedback shift register of length L is a bit string of length L. true / O false Asynchronous stream ciphers provide enhanced security over synchronous | O true / O false ones by generating key streams at random. There exists a primitive polynomial of degree 128 over Z2. true / O false DES and AES are examples of block ciphers. true / O false

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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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?
One potential limitation of a digital signature is that for a given signature σ of a message m corresponding to a public key pk, one could generate a pk', sk' that produces a signature σ' for m, such that σ' = σ. Given a signing function S, a verification function V, that each takes corresponding private and public keys for generating and verifying a signature and is vulnerable to these duplicate keys, please generate S' and V' that are immune to a duplicate keys attack.
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 CTR mode, 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 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 "spider" using CTR mode. Please enter your answer in hex. (Please do **not** enter an 0x, as this has been done.) Ox b) Encrypt the plaintext "spelling" using ECB mode. Please enter your answer in hex. Ox c) Encrypt the…
Describe the working of recursive and iterative queries in DNS. Use figures for the description. A file of F = 3 x 105 bits is distributed to N peers. The server has an upload rate of us = 1 x 105 bps. Each peer has a download rate of di = 1 x 105 bps and an upload rate of u = 30,000 bps. For N = 1 to 10, and for both client-server and P2P architectures, plot a single graph with minimum distribution time on the y-axis and N on the x-axis. Use a table to show all the values for N = 1 to 10 and use the values to plot the graph. Clearly show the calculation only for N = 1, 2, and 3. Explain at least one P2P application (BitTorrent or DHT) in detail.
perform an time and delay analysis of aes encryption algorithm in python.
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 CTR mode, 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 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 "lippo" using CTR mode. Please enter your answer in hex. (Please do **not** enter an Ox, as this has been done.) Ox b) Encrypt the plaintext "lippi" using ECB mode. Please enter your answer in hex. Ox c) Encrypt the…
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3. Decrypt the message "KIE LML MJ" that was encrypted with the affine cipher with the function f(p)=(21.p) mod 26. Hint 1: First find the inverse of 21 modulo 26, å. Then solve the linear congruences for each letter. For example, for K (encoded as 10) solve ā.10= å.21.x (mod 26). Hint 2: Find the encoding of letters below. ABCDEF GHIJK LM NOPQRSTUVWX Y Z 0 12 345 6 789 10o | 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25