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* 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
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"""
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In cryptography, the TRANSPOSITION cipher is a method of encryption where the
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positions of plaintext are shifted a certain number(determined by the key) that
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follows a regular system that results in the permuted text, known as the encrypted
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text. The type of transposition cipher demonstrated under is the ROUTE cipher.
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"""
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def main():
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message = input("Enter message: ")
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key = int(input("Enter key [2-%s]: " % (len(message) - 1)))
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mode = input("Encryption/Decryption [e/d]: ")
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if mode.lower().startswith("e"):
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text = encryptMessage(key, message)
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elif mode.lower().startswith("d"):
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text = decryptMessage(key, message)
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# Append pipe symbol (vertical bar) to identify spaces at the end.
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print("Output:\n%s" % (text + "|"))
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def encryptMessage(key, message):
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"""
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>>> encryptMessage(6, 'Harshil Darji')
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'Hlia rDsahrij'
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"""
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cipherText = [""] * key
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for col in range(key):
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pointer = col
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while pointer < len(message):
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cipherText[col] += message[pointer]
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pointer += key
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return "".join(cipherText)
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def decryptMessage(key, message):
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"""
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>>> decryptMessage(6, 'Hlia rDsahrij')
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'Harshil Darji'
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"""
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numCols = math.ceil(len(message) / key)
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numRows = key
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numShadedBoxes = (numCols * numRows) - len(message)
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plainText = [""] * numCols
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col = 0
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row = 0
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for symbol in message:
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plainText[col] += symbol
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col += 1
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if (
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(col == numCols)
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or (col == numCols - 1)
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and (row >= numRows - numShadedBoxes)
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):
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col = 0
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row += 1
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return "".join(plainText)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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main()
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