mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-24 13:31:07 +00:00
670f952aa6
* Travis CI: Don’t allow bare exceptions * fixup! Format Python code with psf/black push * except IOError: * except IOError: * Update hamming_code.py * IndexError * Get rid of the nonsense logic Co-authored-by: John Law <johnlaw.po@gmail.com>
71 lines
1.7 KiB
Python
71 lines
1.7 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():
|
|
message = input("Enter message: ")
|
|
key = int(input("Enter key [2-%s]: " % (len(message) - 1)))
|
|
mode = input("Encryption/Decryption [e/d]: ")
|
|
|
|
if mode.lower().startswith("e"):
|
|
text = encryptMessage(key, message)
|
|
elif mode.lower().startswith("d"):
|
|
text = decryptMessage(key, message)
|
|
|
|
# Append pipe symbol (vertical bar) to identify spaces at the end.
|
|
print("Output:\n%s" % (text + "|"))
|
|
|
|
|
|
def encryptMessage(key, message):
|
|
"""
|
|
>>> encryptMessage(6, 'Harshil Darji')
|
|
'Hlia rDsahrij'
|
|
"""
|
|
cipherText = [""] * key
|
|
for col in range(key):
|
|
pointer = col
|
|
while pointer < len(message):
|
|
cipherText[col] += message[pointer]
|
|
pointer += key
|
|
return "".join(cipherText)
|
|
|
|
|
|
def decryptMessage(key, message):
|
|
"""
|
|
>>> decryptMessage(6, 'Hlia rDsahrij')
|
|
'Harshil Darji'
|
|
"""
|
|
numCols = math.ceil(len(message) / key)
|
|
numRows = key
|
|
numShadedBoxes = (numCols * numRows) - len(message)
|
|
plainText = [""] * numCols
|
|
col = 0
|
|
row = 0
|
|
|
|
for symbol in message:
|
|
plainText[col] += symbol
|
|
col += 1
|
|
|
|
if (
|
|
(col == numCols)
|
|
or (col == numCols - 1)
|
|
and (row >= numRows - numShadedBoxes)
|
|
):
|
|
col = 0
|
|
row += 1
|
|
|
|
return "".join(plainText)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|
|
main()
|