110 lines
2.7 KiB
Python
110 lines
2.7 KiB
Python
# coding: utf-8
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from argparse import ArgumentParser
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import matplotlib.pyplot as plt
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from lorem import text as loremtext
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def checkArguments():
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args = ArgumentParser(description='Cryptanalyst')
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args.add_argument('-f', '--filename', help='Text to analyze')
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args.add_argument('-s', '--stats', help='Statistics', action='store_true')
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args.add_argument('-d', '--decrypt', help='Decrypt Caesar text', action='store_true')
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return args.parse_args()
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def readCipherText(filename):
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"""
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This read the file passed in argument and return the data of it
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"""
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file = []
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with open(filename, 'r') as f:
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data = f.readlines()
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for entry in data:
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file.append(entry.strip())
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return file
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def stats(file=None):
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"""
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This function get a stats of all letter occurrence in a text
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"""
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if file is None:
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text = loremtext()
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else:
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text = file
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lettersOccurence = {}
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letterUpperToAscii = ord('A') # Get the ASCII code
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for i in range (0, 26):
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lettersOccurence[chr(i + letterUpperToAscii)] = 0
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for line in text:
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for letter in line:
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letter = letter.upper()
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if letter in lettersOccurence:
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lettersOccurence[letter] = lettersOccurence[letter] + 1
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x = [chr(letter + 65) for letter in range(0, 26)]
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y = [lettersOccurence[tmp] for tmp in lettersOccurence]
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largeur = 0.5
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plt.bar(x, y, largeur)
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plt.show()
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def decryptCaesarText(cipherFile):
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"""
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This function breach the caesar ciphertext with all key
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"""
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if cipherFile is None:
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return
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letterAToAscii = ord('A') # Get the ASCII code
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letterZToAscii = ord('Z') # Get the ASCII code
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letteraToAscii = ord('a') # Get the ASCII code
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letterzToAscii = ord('z') # Get the ASCII code
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for key in range (0, 26):
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foo = []
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for line in cipherFile:
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newLine = str()
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for letter in line:
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letter = letter.upper()
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letterAscii = ord(letter)
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if letterAscii >= letterAToAscii and letterAscii <= letterZToAscii:
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newLetter = getNewLetter(letterAscii, letterAToAscii, key)
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elif letterAscii >= letteraToAscii and letterAscii <= letterzToAscii:
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newLetter = getNewLetter(letteraToAscii, key)
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else:
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newLetter = letter
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newLine = newLine + newLetter
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foo.append(newLine)
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print(f"key: {key}")
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print(foo)
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def getNewLetter(letterAscii, letterToAscii, key):
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"""
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This function return the new letter and we substract with the key.
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The function return the new letter into a char
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"""
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letterAscii = letterAscii - letterToAscii
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res = ((letterAscii - key) % 26) + letterToAscii
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return chr(res)
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def main():
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args = checkArguments()
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cipherFile = None
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if args.filename:
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cipherFile = readCipherText(args.filename)
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if args.stats:
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stats(cipherFile)
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if args.decrypt:
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decryptCaesarText(cipherFile)
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if __name__ == "__main__":
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main()
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