For reasons, that will become clear, the version of RSA encryption covered in the lecture is called "naive RSA" in [Sma16]. In practice, it is recommended that RSA be used with some sort of message padding. A standard way is using optimal asymmetric encryption padding (OAEP), as indicated in the lecture. In this question, we will cover a simpler version, which at least makes the scheme semantically secure under chosen plaintext attacks. The CEO of the organization XYZ decides to hold a vote to decide whether employees should be allowed to work from home (WFH) all five days of the work week. All 5 employees of XYZ (excluding the CEO), need to vote either "WFH yes" or "WFH no." To ensure privacy, the CEO asks employees to send their votes by emailing them to the CEO. Furthermore, the CEO tells them to encrypt their votes using her RSA public key e. The messages are encoded as: WFH yes 7→ 100,

For reasons, that will become clear, the version of RSA encryption covered in the lecture is called "naive RSA" in [Sma16]. In practice, it is recommended that RSA be used with some sort of message padding. A standard way is using optimal asymmetric encryption padding (OAEP), as indicated in the lecture. In this question, we will cover a simpler version, which at least makes the scheme semantically secure under chosen plaintext attacks. The CEO of the organization XYZ decides to hold a vote to decide whether employees should be allowed to work from home (WFH) all five days of the work week. All 5 employees of XYZ (excluding the CEO), need to vote either "WFH yes" or "WFH no." To ensure privacy, the CEO asks employees to send their votes by emailing them to the CEO. Furthermore, the CEO tells them to encrypt their votes using her RSA public key e. The messages are encoded as: WFH yes 7→ 100,

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 the following encryption scheme for a block cipher (using the notationfrequently used in class).y1 = ek(x1), y2 = ek(x1 ⊕ x2), y3 = ek(x1 ⊕ x2 ⊕ x3), etc.a. Describe the corresponding decryption scheme.b. Can encryption and/or decryption be run in parallel for this scheme?c. Taking into account that the operation of XOR is cheap, determinewhether or not this scheme improves on ECB mode or not
The Lingala Language of Republic of Congo has 35 letters. Consider an Affine cipher, which encrypts each letter according to the rule: C=(p×k1+k2) mod 35. Here C, p, k1, and k2 are each members in the range 0 to 34, where C represents the ciphertext letter, p the plaintext letter, and k1 and k2 are constant keys. How many possible keys does this affine system have? Explain in details.
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?
A Man-in-the-Middle attack on the Diffie-Hellman key exchange protocol may be effectively carried out if the adversary produces two public-private key pairs for the assault. Could the same assault be carried out with a single pair? Justify and describe the event in full.
c) AES and DES are the two widely used block-ciphers in symmetric cryptography. For every following component of DES, state the comparable element in AES, or describe why it is not required/used in AES. i) XOR of the f function output with the left half of the block ii) The f function iii) Permutation P iv) Swapping of halves of the block
Suppose we have the encoding that enables Carol to mount the cube root attack (see The Cube Root Problem). If Carol sends a message to Bob, supposedly signed by you, will there be anything suspicious and noticeable about the signed message, so that with very little additional computation Bob can detect the forgery? Is there anything Carol can do to make her messages less suspicious? Cuberoot problem: Let's say you pad on the right with random data. You chose that scheme so that there is a negligible probability that anything you sign will be smooth. However, if the public exponent is 3, this enables Carol to forge your signature on virtually any message she chooses! Let's say Carol wants your signature on some message. The message digest of that message is h. Carol pads h on the right with zeroes. She then computes its ordinary cube root and rounds up to an integer r. Now she has forged your signature, because re = r3 = (h padded on the right with a seemingly random number).
A shortcoming of using an elliptic curve E(Fp) for cryptography is the fact that it takes two coordinates to specify a point in E(Fp). However, as discussed briefly at the end of Sect. 6.4.2, the second coordinate actually conveys very little additional information.(b) Alice and Bob decide to use the prime p = 1123 and the elliptic curveE : Y2 = X3 + 54X + 87.Bob sends Alice the x-coordinate x = 278 and the bit β = 0. What point is Bob trying to convey to Alice? What about if instead Bob had sent β = 1?
In block ciphers, if we use AES for encryption, it does not matter whether the cipher is CBC-based or ECB-based (both will have equally strong results). true or false
Consider the following encryption scheme for a block cipher (using the notationfrequently used in class).y1 = ek(x1 ⊕ IV), y2 = ek(x2), y3 = ek(x3), etc.a. Suppose IV is a block consisting entirely of zeros. Which mode ofoperation does the described mode reduce to?b. Describe the corresponding decryption scheme.c. Can encryption and/or decryption be run in parallel for this scheme?
Problem #1Given below is a well-known cryptosystem called affine Caesar cipher, as well as someciphertext generated using the affine Caesar cipher.P = C = Z 26 = {0, 1, 2, ..., 25};K = {(a, b) Z26 Z26 | gcd(a, 26) = 1}y = E([a,b], x) = (ax + b) mod 26,x = D([a,b], y) = a-1 (y – b) mod 26,where x P, y C. Ciphertext sample:VPWOMFUWOFMYMHUNWBBWGCRVVPSFVPUTHUJWMCOMFUOVSVWOVWGSRSFSREOWOQMHKOBMHVPWOUFGHETVWMFOEOVUYVMMZCVGSFEMCCOUEMCHKFMQRUNIUMBRWFUSHSRIUZHSVMBWFNVPUOUGHUVKUEVMMVPUFEMCQWRRPSJUVHCREGHSGKUNVPUOEOVUY For this problem, please do the following:(a) provide an analysis detailing its strength/weakness;(b) attempt to uncover the plaintext associated with the ciphertext;(c) attempt to determine the secret key (a, b) used.
As discussed in Class 05, cryptography is the area of mathematics intended for the study of techniques and principles for transforming information from its original form to another, unintelligible form, so that it can be used only when authorized. According to the definition of encryption, carefully analyze the following situation presented below: For the transmission of encrypted messages between two points A and B, A generates a private key and forwards it to B, A encrypts the message using this same private key and sends this message to B, upon receiving the message, B decrypts the message with the same private key. Regarding the situation presented above, mark the alternative that corresponds to the encryption mode used. A) Cryptographic Abstract;B) Asymmetrical;C) Digital Certification;D) Symmetrical;E) Digital Signature.
With the use of appropriate diagrams, explain the two fundamentallydifferent types of encryption