Shift-Cipher

The Shift Cipher, also known as the Caesar Cipher, is a type of substitution cipher where each letter in the plaintext is replaced by a letter a certain number of positions further down the alphabet. This number of positions is sometimes called a key. The encryption and decryption processes involve shifting the letters by a fixed number of positions, wrapping around to the beginning of the alphabet when necessary.

The encryption formula is E_n(x) = (x + n) mod 26, where x is the plaintext letter, n is the shift value, and mod 26 ensures that the result is within the range of the alphabet.

The decryption formula is D_n(x) = (x - n) mod 26, which is the inverse of the encryption formula.

Installation

You can install the package by cloning the repository then using pip:

git clone https://github.com/droubarka/shift-cipher.git
cd shift-cipher
python3 -m pip install .

Or you can use the following command instead:

python3 -m pip install git+https://github.com/droubarka/shift-cipher.git

Usage

Use the shift_alpha function to shift alphabetic characters:

from shiftcipher import shift_alpha

message = "Hello, World!"
shift = 32

encrypted_message = shift_alpha(message, shift)
decrypted_message = shift_alpha(encrypted_message, shift, reverse=True)

print(encrypted_message) # Output: "Nkrru, Cuxrj!"
print(decrypted_message) # Output: "Hello, World!"

Use the shift_bytes function to applies a byte-level shift:

from shiftcipher import shift_bytes

message = b"Hello, World!"
shift = 128

encrypted_message = shift_bytes(message, shift)
decrypted_message = shift_bytes(encrypted_message, shift, reverse=True)

print(encrypted_message) # Output: b'\xc8\xe5\xec\xec\xef\xac\xa0\xd7\xef\xf2\xec\xe4\xa1'
print(decrypted_message) # Output: b"Hello, World!"

Use the global_shift function to shift different element types:

from shiftcipher import global_shift

data = ['localhost', b'X', True, False, None, 1000]
table = [
	'127.0.0.1', 'localhost',
	'0x58', b'X',
	'true', True,
	'false', False,
	'null', None,
	'1e+3', 1000]
shift = -1

encrypted_data = global_shift(data, table, shift)
decrypted_data = global_shift(encrypted_data, table, shift, reverse=True)

print(encrypted_data) # Output: ['127.0.0.1', '0x58', 'true', 'false', 'null', '1e+3']
print(decrypted_data) # Output: ['localhost',  b'X',   True,   False,   None,   1000 ]

Contributing

Contributions are welcome! If you'd like to contribute to the shift-cipher implementation, please fork the repository and submit a pull request.

License

The shift-cipher implementation is released under the MIT License.