DHBW/Krypto_Grundlagen
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Adding util method to replace invalid input characters

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- Also better type hints
This commit is contained in:
Patrick Müller 2021-10-17 16:54:25 +02:00
parent d4bd9638a4
commit 2bd8dbc6db
4 changed files with 74 additions and 11 deletions
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9
chapter_one/Multiplikative_Chiffre.py
View File

@ -1,9 +1,10 @@
from utils import AlphabetUtils as au
from utils import CipherUtils as cu
ALLOWED_KEYS = [1, 3, 5, 7, 9, 11, 15, 17, 19, 21, 23, 25]
def encrypt_text(cleartext: str, key: int):
def encrypt_text(cleartext: str, key: int) -> str:
"""
Encrypts the given text with the given key
:param cleartext: The text to encrypt
@ -14,6 +15,8 @@ def encrypt_text(cleartext: str, key: int):
if key not in ALLOWED_KEYS:
raise AttributeError
cleartext = cu.transform_invalid_chars(cleartext)
resulting = ''
for char in cleartext:
@ -24,7 +27,7 @@ def encrypt_text(cleartext: str, key: int):
return resulting
def decrypt_text(ciphertext: str, key: int):
def decrypt_text(ciphertext: str, key: int) -> str:
"""
Decrypts the given ciphertext with the given key
:param ciphertext: The text to decrypt
@ -47,7 +50,7 @@ def decrypt_text(ciphertext: str, key: int):
return resulting
def _get_key_reverse(key: int):
def _get_key_reverse(key: int) -> int:
"""
Calculates the decryption key (inverse of the original key) based on the following formula:
s * s' mod 26 = 1

17
chapter_one/Permutations-Chiffre.py
View File

@ -1,15 +1,19 @@
import random
from utils import AlphabetUtils as au
from utils import CipherUtils as cu
def encrypt_text(cleartext: str, key: [int]):
def encrypt_text(cleartext: str, key: [int]) -> str:
"""
Encrypts the given text with the given key
:param cleartext: The text to encrypt
:param key: The key to use. Has to be a list of indices of the alphabet, so [0...25] shuffled
:return: The encrypted text
"""
cleartext = cu.transform_invalid_chars(cleartext)
resulting = ''
for char in cleartext:
@ -21,7 +25,7 @@ def encrypt_text(cleartext: str, key: [int]):
return resulting
def decrypt_text(ciphertext: str, key: [int]):
def decrypt_text(ciphertext: str, key: [int]) -> str:
"""
Decrypts the given ciphertext with the given key
:param ciphertext: The text to decrypt
@ -39,7 +43,7 @@ def decrypt_text(ciphertext: str, key: [int]):
return resulting
def generate_key():
def generate_key() -> [int]:
"""
Generates a key that can be used for this cipher.
:return: The key as a list of indices
@ -51,7 +55,12 @@ def generate_key():
return indices
def generate_key_with_keyword(keyword: str):
def generate_key_with_keyword(keyword: str) -> [int]:
"""
Generates a key that can be used for this cipher by using the given keyword as a starting point
:param keyword: The keyword to use to generate the key
:return: The key as a list of indices
"""
result = []
for char in keyword:

9
chapter_one/Tausch-Chiffre.py
View File

@ -1,9 +1,10 @@
from utils import AlphabetUtils as au
from utils import CipherUtils as cu
ALLOWED_KEYS = [1, 3, 5, 7, 9, 11, 15, 17, 19, 21, 23, 25]
def encrypt_text(cleartext: str, key1: int, key2: int):
def encrypt_text(cleartext: str, key1: int, key2: int) -> str:
"""
Encrypts the given text with the given keys
:param cleartext: The text to encrypt
@ -19,6 +20,8 @@ def encrypt_text(cleartext: str, key1: int, key2: int):
if key2 < 0 or key2 > 25:
raise AttributeError
cleartext = cu.transform_invalid_chars(cleartext)
resulting = ''
for char in cleartext:
@ -29,7 +32,7 @@ def encrypt_text(cleartext: str, key1: int, key2: int):
return resulting
def decrypt_text(ciphertext: str, key1: int, key2: int):
def decrypt_text(ciphertext: str, key1: int, key2: int) -> str:
"""
Decrypts the given ciphertext with the given keys
:param ciphertext: The text to decrypt
@ -57,7 +60,7 @@ def decrypt_text(ciphertext: str, key1: int, key2: int):
return resulting
def _get_key_reverse(key: int):
def _get_key_reverse(key: int) -> int:
"""
Calculates the decryption key (inverse of the original key) based on the following formula:
s * s' mod 26 = 1

50
utils/CipherUtils.py
View File

@ -1,10 +1,40 @@
import AlphabetUtils as au
from utils import AlphabetUtils as au
GERMAN_FREQUENCY_PROFILE = [
0.0651,
0.0189,
0.0306,
0.0508,
0.1740,
0.0166,
0.0301,
0.0476,
0.0755,
0.0027,
0.0121,
0.0344,
0.0253,
0.0978,
0.0251,
0.0079,
0.0002,
0.0700,
0.0727,
0.0615,
0.0435,
0.0067,
0.0189,
0.0003,
0.0004,
0.0113
]
def calculate_frequency(text: str, fancy_printing: bool = False):
"""
Calculates the frequency of every letter in the german alphabet for the given text
:param text: The text to calculate the letter frequency for
:param fancy_printing: Whether to print the frequencies to the console
:return: A list of frequencies, where index 0 contains the frequency of a in percent and so on.
"""
occurrence_count = [0 for i in range(26)]
@ -26,6 +56,24 @@ def calculate_frequency(text: str, fancy_printing: bool = False):
return occurrence_frequency
def transform_invalid_chars(input: str) -> str:
"""
Transforms invalid characters like german umlauts into their allowed alternatives
:param input: The text to check
:return: The improved text
"""
res = input
res = res.replace('ä', 'ae')
res = res.replace('A', 'Ae')
res = res.replace('ö', 'oe')
res = res.replace('Ö', 'Oe')
res = res.replace('ü', 'ue')
res = res.replace('Ü', 'Ue')
res = res.replace('ß', 'ss')
return res
if __name__ == '__main__':
print(
calculate_frequency('Hier den Text eingeben, für den die Wahrscheinlichkeiten berechnet werden sollen', True))