mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-18 17:20:16 +00:00
fc33c50593
updates: - [github.com/astral-sh/ruff-pre-commit: v0.4.10 → v0.5.0](https://github.com/astral-sh/ruff-pre-commit/compare/v0.4.10...v0.5.0) - [github.com/pre-commit/mirrors-mypy: v1.10.0 → v1.10.1](https://github.com/pre-commit/mirrors-mypy/compare/v1.10.0...v1.10.1) Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
69 lines
1.8 KiB
Python
69 lines
1.8 KiB
Python
import math
|
|
|
|
"""
|
|
In cryptography, the TRANSPOSITION cipher is a method of encryption where the
|
|
positions of plaintext are shifted a certain number(determined by the key) that
|
|
follows a regular system that results in the permuted text, known as the encrypted
|
|
text. The type of transposition cipher demonstrated under is the ROUTE cipher.
|
|
"""
|
|
|
|
|
|
def main() -> None:
|
|
message = input("Enter message: ")
|
|
key = int(input(f"Enter key [2-{len(message) - 1}]: "))
|
|
mode = input("Encryption/Decryption [e/d]: ")
|
|
|
|
if mode.lower().startswith("e"):
|
|
text = encrypt_message(key, message)
|
|
elif mode.lower().startswith("d"):
|
|
text = decrypt_message(key, message)
|
|
|
|
# Append pipe symbol (vertical bar) to identify spaces at the end.
|
|
print(f"Output:\n{text + '|'}")
|
|
|
|
|
|
def encrypt_message(key: int, message: str) -> str:
|
|
"""
|
|
>>> encrypt_message(6, 'Harshil Darji')
|
|
'Hlia rDsahrij'
|
|
"""
|
|
cipher_text = [""] * key
|
|
for col in range(key):
|
|
pointer = col
|
|
while pointer < len(message):
|
|
cipher_text[col] += message[pointer]
|
|
pointer += key
|
|
return "".join(cipher_text)
|
|
|
|
|
|
def decrypt_message(key: int, message: str) -> str:
|
|
"""
|
|
>>> decrypt_message(6, 'Hlia rDsahrij')
|
|
'Harshil Darji'
|
|
"""
|
|
num_cols = math.ceil(len(message) / key)
|
|
num_rows = key
|
|
num_shaded_boxes = (num_cols * num_rows) - len(message)
|
|
plain_text = [""] * num_cols
|
|
col = 0
|
|
row = 0
|
|
|
|
for symbol in message:
|
|
plain_text[col] += symbol
|
|
col += 1
|
|
|
|
if (col == num_cols) or (
|
|
(col == num_cols - 1) and (row >= num_rows - num_shaded_boxes)
|
|
):
|
|
col = 0
|
|
row += 1
|
|
|
|
return "".join(plain_text)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|
|
main()
|