Random monoalphabet cipher. The Caesar cipher, which shifts all letters by a fixed amount, is far too 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: FEATHRZYXWVUSQPONMLKJ Now encrypt the letters as follows: ABCDEFGHIJKLMNOPQRSTUV IGDC B XYZ FEATHRZYXWVUSOPONMLKJIGDCB 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.

Random monoalphabet cipher. The Caesar cipher, which shifts all letters by a fixed amount, is far too 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: FEATHRZYXWVUSQPONMLKJ Now encrypt the letters as follows: ABCDEFGHIJKLMNOPQRSTUV IGDC B XYZ FEATHRZYXWVUSOPONMLKJIGDCB 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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Python The Dan Cipher works like this: shift the first lowercase character to the right by 1, the second lowercase character to the right by 2, and so on. Characters that are not lowercase characters are not changed. Write a program that takes a string and prints the result of applying the Dan Cipher.
Use RSA cryptography with public key p = 11 q = 13 and e = 23 to encrypt your unique student number. You need to remove all the consecutive zeros in the middle of the student number, then divide your student number into the blocks of two-digits from left to right. Afterwards, you will need to encrypt the resulted list of numbers by RSA. For example, the student number 13060009867 becomes the list of [13, 6, 98, 67]. Then you need to directly encrypt the numbers 13, 6 , 98 and 67 by RSA.
A Caesar cipher is a simple substitution cipher based on the idea of shifting each letter of the plaintext message a fixed number (called the key) of positions in the alphabet. For example, if the key value is 2, the word "Sourpuss" would be encoded as "Uqwtrwuu." The original message can be recovered by “reencoding" it using the negative of the key. Write a program that can encode and decode Caesar ciphers. The in- put to the program will be a string of plaintext and the value of the key. The output will be an encoded message where each character in the orig- inal message is replaced by shifting it key characters in the Unicode char- acter set. For example, if ch is a character in the string and key is the amount to shift, then the character that replaces ch can be calculated as: chr (ord (ch) + key). 62
Substitution ciphers are encryption/decryption algorithms that replace one letter or number with another. The first attested use of a substitution cipher in military affairs was by Julius Caesar, described by him in Gallic Wars (cf. Kahn pp83-84). In caesar cipher , you replace each letter by 3rd letter on. If it is out of bound (later than Z), then round to the head (letter A) and continue the shift. For example:meet me after the toga party PHHW PH DIWHU WKH WRJD SDUWB Please write a program in Java to implement the Caesar Cipher: a. Implement the encryption algorithm. Ask the user to input one all lower case normal sentence (called plaintext) using the nextLine method, and then output the encrypted text (called ciphertext). b. Implement the decryption algorithm. Ask the user to input one encrypted sentence (i.e. ciphertext) using the nextLine method, and then output the decrypted text (i.e. plaintext).
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…
a) Implement Playfair Cipher to get the ciphertext. Here, plaintext and key is given. Plaintext = "Fitness is the key", Key = "CRYPT".
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…
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The Reflection algorithm can be used to encrypt a C-string (character array terminated with the null character) before it is transmitted over the Internet. The Reflection algorithm works as follows: Each letter in the message is converted to the letter in that is 13 positions to the right of that letter in the English alphabet. If the end of the alphabet is reached, counting continues from the first letter in the alphabet. The case of the letters must be maintained. For example,'M' →'Z', 'x' → 'k', 'A' → 'N'The numeric characters ('0' to '9') are shifted 5 positions to the right of that number in the character set '0' to '9'. If ‘9’ is reached, counting continues from ‘0’. For example,'0' → '5', '2' →'7', '8' → '3' All other characters are left as they are. a) What would the following string be encrypted to by the Reflection algorithm?“Call me at 662-2002 Ext 85393” b) Write a function, getPosition, which finds the position of a letter in the alphabet regardless of the case of the…
Encrypt Caesar cipher is a kind of substitution cipher. Instead of using a substitution table, the alphabets are rotated by a number (a key). For example, if the key is 3, plaintext alphabet a would become d, and plaintext alphabet z would become c. Write a program that implements the Caesar Cipher. You program will first prompt for the key and then for the mode (E for encryption and D for decryption) and finally for the message to be encrypted / decrypted. Your program will then output the encryption / decryption message. For this question, the input message may consists of any character, the program should encrypt or small letter case a to z only. All other characters should be kept intact after encryption or decryption.
Implement the first round of AES ( Advanced Encryption Standard ) in python. Given a message with 128 bits, two subkeys subkey0 and subkey1, your program should be able to perform one AddKey before Round 1 and the corresponding operations (SubBytes, ShiftRows, Mix-Columns, and AddKey) in Round 1, and output the result of the encryption after Round 1.