CaesarCipher Program
Description
Caesar Cipher is an ancient encryption technique. We can use it to transmit encrypted data.To encrypt the text message, each character in the original message is shifted N positions, where N is called key.
For example, if N = 1, then the message
Computer Science
Becomes
Dpnqvufs!Tdjfodf
The encrypted message can be decrypted to the original message
by shifting back every character N positions. Shifting N positions forward and backward is achieved by adding or subtracting N to the character's ASCII code.
This program reads text data from a data file and N from the keyboard, then encrypts the text and saves the encrypted text to another file.
Note:
The ASCII value resulting from encryption should fall between 32 and 126 (printable characters).
For example, if the program adds 8 (value of N) to 122 (ASCII code for ‘z’), the result is 130 which is out of the range of printable characters.
So the program should “wrap around” to get 36. However, this program doesn't provide the solution of wrapping around.
Associated Concepts:
File I/O
Method
Method
Algorithm:
main method:
Write encrypt method definition
Create a File object and associate it with the data file and
then create a Scanner object and associate it with the File object
Create a FileWriter object and associate it with the output file and
then create a PrintWriter object and associate it with the FileWriter object
Prompt the user to enter the encryption key
Call encrypt method and pass inFile, outFile, and key as arguments
Close both inFile and outFile objects
then create a Scanner object and associate it with the File object
Create a FileWriter object and associate it with the output file and
then create a PrintWriter object and associate it with the FileWriter object
Prompt the user to enter the encryption key
Call encrypt method and pass inFile, outFile, and key as arguments
Close both inFile and outFile objects
Write encrypt method definition
while loop (as long as the data file has data item):
read the entire line of data
Use a loop to retrieve each character in the line:
Encrypt the character with the key (no wrap around)
Append the encrypted character to the encrypted line
Write the encrypted line to the output file
read the entire line of data
Use a loop to retrieve each character in the line:
Encrypt the character with the key (no wrap around)
Append the encrypted character to the encrypted line
Write the encrypted line to the output file
Source Code
Input File CaesarCipher_Data.txt
Sample Run
Output File CaesarCipher_Result.txt
