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Cryptography. The science of developing secret codes has interested many people for centuries. Some of the simplest codes involve replacing a...




Prgogram for C;Cryptography. The science of developing secret codes has interested many people for centuries.;Some of the simplest codes involve replacing a character, or a group of characters, with another;character, or group of characters. To easily decode these messages, the decoder needs the ?key?;that shows the replacement characters. For your second project you will write two programs that;do the following;1. Write a program to implement a simple code that replaces each character by another character;that is a fixed number of positions away in the collating sequence. For example, if each character;is replaced by the character that is two characters to the right, then the letter ?a? is replaced by the;letter ?c?, the letter ?b? is replaced by the letter ?d?, and so on. Your program should be able to;read a text in a file (create your own, name it ?message.txt?), and then generate a new file that;contains the coded text using this encryption technique (name it ?encryptMessage.txt?). Do not;change the newline characters or the EOF character.;Your program should allow the user to choose the ?key? for encryption, i.e. if the user enters 4;then each character is replaced by a character that is 4 characters to the right or if the user enters;-4 then each character is replaced by 4 characters to the left. Use an ASCII character chart to;make sure that you are replacing the characters properly.;Your program should also create a file called ?key.txt? that contains the key used to encrypt the;message.;2. Write a program that will decode the encryption scheme in problem 1. Test your program;using the files generated in 1.;What to turn in: For this project you will only need to turn in the code (just like you have done;for home works and project 1) and the text files used/generated for part 1. Your *.c file must be;well documented, i.e. you must include comments throughout the program. The code must;readable i.e. user proper spacing and indentation. I will be testing your programs using the files;you provide as well as my own message file.


Paper#70883 | Written in 18-Jul-2015

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