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XOR Cipher: doctests and bug fixes (#10840)

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* Fixed bug with key modulus wrapping. Should be wrapping on 256, not 255.

* Fixed bug with incorrect assertion type in decrypt function.

* Added doctests for 4 out of 6 methods
This commit is contained in:
Farzad Hayat 2023-10-29 22:57:04 +10:00 committed by GitHub
parent cc22d0b0ba
commit 7c1dfec086
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1 changed files with 82 additions and 9 deletions
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91
ciphers/xor_cipher.py
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@ -35,6 +35,22 @@ class XORCipher:
output: encrypted string 'content' as a list of chars
if key not passed the method uses the key by the constructor.
otherwise key = 1
Empty list
>>> XORCipher().encrypt("", 5)
[]
One key
>>> XORCipher().encrypt("hallo welt", 1)
['i', '`', 'm', 'm', 'n', '!', 'v', 'd', 'm', 'u']
Normal key
>>> XORCipher().encrypt("HALLO WELT", 32)
['h', 'a', 'l', 'l', 'o', '\\x00', 'w', 'e', 'l', 't']
Key greater than 255
>>> XORCipher().encrypt("hallo welt", 256)
['h', 'a', 'l', 'l', 'o', ' ', 'w', 'e', 'l', 't']
"""
# precondition
@ -44,7 +60,7 @@ class XORCipher:
key = key or self.__key or 1
# make sure key is an appropriate size
key %= 255
key %= 256
return [chr(ord(ch) ^ key) for ch in content]
@ -54,16 +70,32 @@ class XORCipher:
output: decrypted string 'content' as a list of chars
if key not passed the method uses the key by the constructor.
otherwise key = 1
Empty list
>>> XORCipher().decrypt("", 5)
[]
One key
>>> XORCipher().decrypt("hallo welt", 1)
['i', '`', 'm', 'm', 'n', '!', 'v', 'd', 'm', 'u']
Normal key
>>> XORCipher().decrypt("HALLO WELT", 32)
['h', 'a', 'l', 'l', 'o', '\\x00', 'w', 'e', 'l', 't']
Key greater than 255
>>> XORCipher().decrypt("hallo welt", 256)
['h', 'a', 'l', 'l', 'o', ' ', 'w', 'e', 'l', 't']
"""
# precondition
assert isinstance(key, int)
assert isinstance(content, list)
assert isinstance(content, str)
key = key or self.__key or 1
# make sure key is an appropriate size
key %= 255
key %= 256
return [chr(ord(ch) ^ key) for ch in content]
@ -73,6 +105,22 @@ class XORCipher:
output: encrypted string 'content'
if key not passed the method uses the key by the constructor.
otherwise key = 1
Empty list
>>> XORCipher().encrypt_string("", 5)
''
One key
>>> XORCipher().encrypt_string("hallo welt", 1)
'i`mmn!vdmu'
Normal key
>>> XORCipher().encrypt_string("HALLO WELT", 32)
'hallo\\x00welt'
Key greater than 255
>>> XORCipher().encrypt_string("hallo welt", 256)
'hallo welt'
"""
# precondition
@ -81,9 +129,8 @@ class XORCipher:
key = key or self.__key or 1
# make sure key can be any size
while key > 255:
key -= 255
# make sure key is an appropriate size
key %= 256
# This will be returned
ans = ""
@ -99,6 +146,22 @@ class XORCipher:
output: decrypted string 'content'
if key not passed the method uses the key by the constructor.
otherwise key = 1
Empty list
>>> XORCipher().decrypt_string("", 5)
''
One key
>>> XORCipher().decrypt_string("hallo welt", 1)
'i`mmn!vdmu'
Normal key
>>> XORCipher().decrypt_string("HALLO WELT", 32)
'hallo\\x00welt'
Key greater than 255
>>> XORCipher().decrypt_string("hallo welt", 256)
'hallo welt'
"""
# precondition
@ -107,9 +170,8 @@ class XORCipher:
key = key or self.__key or 1
# make sure key can be any size
while key > 255:
key -= 255
# make sure key is an appropriate size
key %= 256
# This will be returned
ans = ""
@ -132,6 +194,9 @@ class XORCipher:
assert isinstance(file, str)
assert isinstance(key, int)
# make sure key is an appropriate size
key %= 256
try:
with open(file) as fin, open("encrypt.out", "w+") as fout:
# actual encrypt-process
@ -156,6 +221,9 @@ class XORCipher:
assert isinstance(file, str)
assert isinstance(key, int)
# make sure key is an appropriate size
key %= 256
try:
with open(file) as fin, open("decrypt.out", "w+") as fout:
# actual encrypt-process
@ -168,6 +236,11 @@ class XORCipher:
return True
if __name__ == "__main__":
from doctest import testmod
testmod()
# Tests
# crypt = XORCipher()
# key = 67