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practical.py
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practical.py
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#!/usr/bin/env python
"""
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or
distribute this software, either in source code form or as a compiled
binary, for any purpose, commercial or non-commercial, and by any
means.
In jurisdictions that recognize copyright laws, the author or authors
of this software dedicate any and all copyright interest in the
software to the public domain. We make this dedication for the benefit
of the public at large and to the detriment of our heirs and
successors. We intend this dedication to be an overt act of
relinquishment in perpetuity of all present and future rights to this
software under copyright law.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
For more information, please refer to <http://unlicense.org>
"""
import os
import re
import random
import sys
__all__, __version__ = ["Practical"], "0.2.3"
class Practical(object):
"""
The Practical Cipher.
"""
def __init__(self, table=None):
"""
Sets the used conversion table.
"""
self.table = table or [
["A", "B", "C", "D", "E", "F"],
["G", "H", "I", "J", "K", "L"],
["M", "N", "O", "P", "Q", "R"],
["S", "T", "U", "V", "W", "X"],
["Y", "Z", "0", "1", "2", "3"],
["4", "5", "6", "7", "8", "9"]
]
def __crypt(self, text, key, mode):
"""
Returns the crypted text.
"""
text = re.sub("[^A-Z0-9]", "", text.upper())
key = re.sub("[^A-Z0-9]", "", key.upper())
if len(text) != len(key):
raise Exception("Key length does not match")
def lookup(symbol, table="".join([x for y in self.table for x in y])):
return reversed(divmod(table.index(symbol), 6))
output = ""
for i in range(len(text)):
tx, ty = lookup(text[i])
kx, ky = lookup(key[i])
rx = mode(tx, kx) % 6
ry = mode(ty, ky) % 6
output += self.table[ry][rx]
return output
def encrypt(self, text, key):
"""
Returns the encrypted text.
"""
return self.__crypt(text, key, lambda x, y: (x + y))
def decrypt(self, text, key):
"""
Returns the decrypted text.
"""
return self.__crypt(text, key, lambda x, y: (x - y))
def key(self, size=5, cols=5, rows=15):
"""
Returns a new random key.
"""
key, r = "", random.SystemRandom()
for row in range(rows):
for col in range(cols):
for i in range(size):
x = r.randint(0, 5)
y = r.randint(0, 5)
key += self.table[y][x]
else:
key += " "
else:
key += "\n"
if (row + 1) % 5 == 0:
key += "\n"
return key.rstrip()
def main(script, command="--help", key=None, *text):
"""
Usage: %s COMMAND [KEY TEXT...]
Commands:
-e, --encrypt Encrypts the given text
-d, --decrypt Decrypts the given text
-k, --key Shows a new random key
-h, --help Shows this text
-l, --license Shows the license
-v, --version Shows the version
Report bugs to <christian@uhsat.de>
"""
try:
script = os.path.basename(script)
if command in ("/?", "-h", "--help"):
print(re.sub("(?m)^ {4}", "", main.__doc__ % script).strip())
elif command in ("-l", "--license"):
print(__doc__.strip())
elif command in ("-v", "--version"):
print("Practical Cipher " + __version__)
elif command in ("-e", "--encrypt") and key and text:
print(Practical().encrypt(" ".join(text), key))
elif command in ("-d", "--decrypt") and key and text:
print(Practical().decrypt(" ".join(text), key))
elif command in ("-k", "--key"):
print(Practical().key())
else:
print("Unknown command or parameter not given.")
print("Please use --help for help on commands.")
return 2 # Incorrect usage
except Exception as ex:
return "%s error: %s" % (script, ex)
if __name__ == "__main__":
sys.exit(main(*sys.argv))