Problem 3. Two texts were encrypted with a Vigenère cipher, both using the same key. The ciphertexts are We found out that the first message begins with HELLOBOB, and ends with ALICE, but we don't know what is in between. ALLYY TUJRM ZKXAT BXAMP OIGKE LVRXS ZBCMH YNHLC VSIMV TVIX AHVRK FOKZJ EKTR

Problem 3. Two texts were encrypted with a Vigenère cipher, both using the same key. The ciphertexts are We found out that the first message begins with HELLOBOB, and ends with ALICE, but we don't know what is in between. ALLYY TUJRM ZKXAT BXAMP OIGKE LVRXS ZBCMH YNHLC VSIMV TVIX AHVRK FOKZJ EKTR

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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The Caesar Cipher Algorithm was introduced in Week #1. Encryption is the act of encoding a message with the intent of allowing only authorized people the knowledge of how to read that message. An encrypted message can be decoded, allowing the secured content to be read after decryption. Recall that the Caesar Cipher uses alphabets as the primary source of information but shifted a certain number of letters to the left or right as a key to create the encrypted data. The Caesar Cipher is easily hacked because of the simple technique used to build the key that encrypts and decrypts the data. In this lab, the key is the number of alphabets shifted, and the direction is always toward the increasing alphabetical order. This provides 26 ways of encrypting a message and therefore makes it easier to be hacked by guessing the key within the range of 0 - 25. Write the function caesar_hack( ) that takes three parameters: a Caesar Cipher encrypted message, an alphabet list, and the original…
The Caesar Cipher Algorithm was introduced in Week #1. Encryption is the act of encoding a message with the intent of allowing only authorized people the knowledge of how to read that message. An encrypted message can be decoded, allowing the secured content to be read after decryption. Recall that the Caesar Cipher uses alphabets as the primary source of information but shifted a certain number of letters to the left or right as a key to create the encrypted data. The Caesar Cipher is easily hacked because of the simple technique used to build the key that encrypts and decrypts the data. In this lab, the key is the number of alphabets shifted, and the direction is always toward the increasing alphabetical order. This provides 26 ways of encrypting a message and therefore makes it easier to be hacked by guessing the key within the range of 0 - 25. Write the function caesar_hack( ) that takes three parameters: a Caesar Cipher encrypted message, an alphabet list, and the original…
A cryptography student has accidentally used the same keystream to encrypt two different messages, M1M1 and M2M2. We know that the ciphertexts are C1=0x4ab397cf20db1ce0C1=0x4ab397cf20db1ce0 and C2=0x2f7fded503744af5C2=0x2f7fded503744af5. We also happen to know that M1=0xbc66dac8daeee8e2M1=0xbc66dac8daeee8e2. a) What is M2M2 in hexadecimal? Please give your answer a leading 0x and use lowercase letters only. b) What is the keystream? Please give your answer a leading 0x and use lowercase letters only. Hint: These are all 8 byte numbers and will fit in an unsigned long type on most systems.
Alice sets up an RSA public/private key, but instead of using two primes, she chooses three primes p, q, and r and she uses n=pqr as her RSA-style modulus. She chooses an encryption exponent e and calculates a decryption exponent d. Encryption and Decryption are defined: C ≡ me mod n and m ≡ Cd mod n where C is the ciphertext corresponding to the message m. Decryption: de ≡ 1 mod φ(n) | Let p = 5, q = 7, r = 3, e = 11, and the decryption exponent d = -13. n = 105 & φ(n) = 48 Q: Alice upgrades to three primes that are each 200 digits long. How many digits does n have?
In cryptography, the Caesar cipher is a type of scroll cipher and is one of the simplest and best-known ciphers. When encrypting a message in the Caesar cipher, each letter is usually replaced by the letter three letters in the alphabet. Let the alphabetic scrollback look like this: aw w ww ww m ww w ww w vwwwwwww www ww wwm w w wwwm www ww defg hijkI mnop 9rstuvwxy z abc a bcd efghilj kI P9rstu v w xy z m Keep the encryption in the Python dictionary structure. www ww Write a Python program that takes the three-letter message as input and prints the encrypted message. Guidance: An empty string can be inserted one by one by replacing the letters of the input. wwwwwwwwwww www wn ww wn ww w www wwh m Entry: Message: kar Encrypted message: hxo Entry: Message: yel Encrypted message: vbi Entry: Message: ses Encrypted message: pbp Entry: Message: mtk Encrypted message: jqh
Alice uses a shift cipher with a shift of 4 to encrypt her message to Bob. If the ciphertext she obtains is "ksshpygo", what is her message in plaintext?
IH A cryptography student has accidentally used the same keystream to encrypt two different messages, M1 and M2. We know that the ciphertexts are C¡ = 0x2e38ac20ƒe51b68c and C2 = 0x638cd0bla9114b4d. We also happen to know that M1 = 0x2b1d510e6a67ae98. a) What is M2 in hexadecimal? Please give your answer a leading Ox and use lowercase letters only. b) What is the keystream? Please give your answer a leading Ox and use lowercase letters only.
Suppose the parameters for an instance of the RSA cryptosystem are N = 26671, e = 3, and d 17563. = Decrypt the message y Decrypt the message y = 6666. = 1576.
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?
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.
suppose the RSA cryptosystem is used for sending secret messages with the private key (15,3) and the cipher text "4" is received. what is the plaintext?
Let's assume that Bob and Alice share a secret key in a symmetric key system. Bob wishes tobegin a conversation with Alice, and sends her a message that essentially says "let's talk". Aliceis suspicious that the person contacting her might not be Bob, so Alice generates a single-userandom number (a nonce) and sends it to Bob. Bob encrypts the nonce with the secret key heshares with Alice and sends it back. Alice decrypts this message and retrieves the same nonceshe sent to Bob. Which of the following is true, provided the secret key K has not been compromised?