P8.7 Random monoalphabet cipher. The Caesar cipher, which shifts all letters by a fixed amount, is far toc easy to crack. Here is a better idea. As the key, don't use numbers but words. Suppose the key word is FEATHER. Then first remove duplicate letters, yielding FEATHR, and append the other letters of the alphabet in reverse order: F EATHRZYXWVUSQPONMLKJIGDC B Now encrypt the letters as follows: ABCD EFGHI JKLMNO P QR STUVWXYZ FEATHRZY XWVUS QP ON MLKJIG D C B Write a program that encrypts or decrypts a file using this cipher. For example, crypt -d -kFEATHER encrypt.txt output.txt decrypts a file using the keyword FEATHER. It is an error not to supply a keyword.

P8.7 Random monoalphabet cipher. The Caesar cipher, which shifts all letters by a fixed amount, is far toc easy to crack. Here is a better idea. As the key, don't use numbers but words. Suppose the key word is FEATHER. Then first remove duplicate letters, yielding FEATHR, and append the other letters of the alphabet in reverse order: F EATHRZYXWVUSQPONMLKJIGDC B Now encrypt the letters as follows: ABCD EFGHI JKLMNO P QR STUVWXYZ FEATHRZY XWVUS QP ON MLKJIG D C B Write a program that encrypts or decrypts a file using this cipher. For example, crypt -d -kFEATHER encrypt.txt output.txt decrypts a file using the keyword FEATHER. It is an error not to supply a keyword.

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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I need help with the following problem: A ciphertext was generated using an affine cipher. The most frequent letter in the ciphertext is “C” and the second most frequent letter is “V”. Break the code. Assume that the most frequent letter in English is “E” and the second most frequent letter is “T”.
The 141 cipher of an input string of letters changes the letters whose index is even (note: zero is even) by shifting it one position to the right in the alphabet. Thus 'a' becomes 'b', 'b' becomes 'c, . z' becomes 'a. If the index of a letter is odd then the letter is shifted four positions to the right, so'a' becomes 'e, 'b' becomes 'f. . w' becomes 'a', 'x' becomes 'b', etc. For example if the plaintext input is 'banana', the 141 encryted text is 'ceoeoe' Define a function called code141 () that takes a string input parameter consisting of lower case alphabetic characters and returns a string which is the 141 encryption of the input.
4. Encryption is used to secure data messages in computer networks. One possible way of encrypting text consists of rewriting the text by including first the characters found at even indexes (starting from 0) followed by the characters stored at odd indexes, while ignoring whitespace characters. For instance, the String "Exam is fun" can be encoded using the previously explained technique as "Easfnxmiu". To be able to recover the original message based on the encrypted version of the message, some additional information should be added to the encrypted message, namely, the number of characters found at even indexes, the number of characters found at odd indexes, and the indexes at which the white space characters existed in the original message. In this way, reconsidering our previous example, the string "Exam is fun" can be encoded using the previously explained technique as "5 4 4 7 Easfnxmiu". This is particularly true since the original message had 5 characters at even indexes…
Implement a subroutine of the Caesar shift encryption. It is a simple substitution encryption algorithm, in which each letter is replaced by a letter with a fixed number of offset down in the alphabet. For example, with a shift offset of 3, A would become D, and B would be replaced by E, and so on.
Substitution Cipher is an old technique that substitutes one thing for another. For example, alphabet messages can be ciphered by applying the following substitution. plaintext: abcdefghijklmnopqrstuvwxyz | | V Vciphertext: mnbvcxzasdfghjklpoiuytrewq However, this type of ciphering produces patterns since the same plaintext strings produce the same cipher text. Polyalphabetic Cipher, on the other hand mitigates this problem as plaintext characters are not always replaced with the same cipher text character. The replacement of each character dependson a key as well as on the position of the character in the text; for example, by using a formula such as: for (int i=0; i < length of P; i++) C[i] = P[i] + K + (i mod 3) In essence, if the key, K, is choses as K=10, then 10 is added to characters in position 0, 3, 6, …; and 11 is added for those in…
Write a Python program to implement Caesar cipher. Caesar cipher is used to encrypt text by replacing each letter by another letter that comes after it in the alphabet by a fixed number of letters (encryption number n). If the last letter of the alphabet (letter 'z') is reached, the program continues to count from the beginning of the alphabet (letter 'a'). The user enters the text and the encryption number (n), and the program prints the encrypted text. The program can be used to decrypt an encrypted text by entering the encrypted text and the negative value of encryption number (-n).
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…
I want Examples on el gamal cipher i want 2 Examples like this Example of ElGamal encryption Alice chooses pA = 107, α A = 2, dA = 67, and she computes β A = 267 ≡ 94 (mod 107). Her public key is ( pA, α A, β A) = (2,67,94), and her private key is dA = 67. Bob wants to send the message "B" (66 in ASCII) to Alice. He chooses a random integer k = 45 and encrypts M = 66 as (r, t) = ( αA k , βA kM) ≡ (245, 944566) ≡ (28, 9) (mod 107). He sends the encrypted message (28, 9) to Alice. Alice receives the message ( r, t) = (28, 9), and using her private key dA = 67 she decrypts to tr−dA = 9⋅28−67 ≡ 9⋅28106−67 ≡ 9⋅43 ≡ 66 (mod 107)
Assume the cryptanalist has two pairs (x, y1) and (, y2) such that yl = DES(K, x) and y2 = DES(K,¤). Build a exhaustive key search which requires only 255 encryption to find out K. (This would be a slight improvement over the total number of 256 keys).
a) Implement Playfair Cipher to get the ciphertext. Here, plaintext and key is given. Plaintext = "Fitness is the key", Key = "CRYPT".
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