The permutation ciphers are used to generate a ciphertext (encrypted text) by re-arranging the position of the letters in a given plaintext.
How does it work?
Select the block size (n) and a permutation.
Divide a given plaintext into blocks of n letters and use ‘x’ as padding, if necessary.
Apply a permutation to each block and generate the encrypted ciphertext.For example, for n = 4 and permutation of (2, 1, 4, 3) Unencrypted plaintext is gentlemen do not read each other’s mail 1234 1234 1234 1234 1234 1234 1234 1234 1234 1234 gentlemendo not readeachother’smailx2143 2143 2143 2143 2143 2143 2143 2143 2143 2143 egtn elem nod n to r ae dae hco htre s’m iaxlEncrypted ciphertext is egtnelem nodn tor ae daehco htres’m iaxl
The program needs to get the following information from the user:
To encrypt: a text file that includes the plaintext, and a block size and the permutationinformation via standard input (keyboard).
To decrypt: a binary file that includes an encrypted ciphertext, and a block size and thepermutation information via standard input (keyboard). Here’s what a sample run should look like:> ./PermCipher Usage: ./PermCipher option -i InputFileName -o OutputFileName Options: -e Encrypt-d Decrypt> ./PermCipher -e -i PlaintextFile -o CiphertextFile Welcome to the Permutation Cipher Selected Mode: Encrypt Input File: PlaintextFileOutput File: CiphertextFile Please enter the block size (2-8) and the permutation (e.g., 4 2413): 4 2143 Encrypted ciphertext file: egtnelem nodn tor ae daehco htres’m iaxl> ./PermCipher -d -i CiphertextFile -o PlaintextFile Welcome to the Permutation Cipher Selected Mode: Decrypt Input File: CiphertextFileOutput File: PlaintextFile Please enter the block size (2-8) and the permutation (e.g., 4 2413): 4 2143 Decrypted ciphertext file: gentlemen do not read each other’s mailThe program should be able to process up to 8 characters at each block with a minimum of 2 characters. Submit your makefile, source code (encrypt.h encrypt.cpp, decrypt.h, decrypt.cpp, main.cpp) and test files to your BitBucket repository.
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