fix(mypy): type annotations for cipher algorithms (TheAlgorithms#4306)

* fix(mypy): type annotations for cipher algorithms

* Update mypy workflow to include cipher directory

* fix: mypy errors in hill_cipher.py

* fix build errors

Author: dhruvmanila

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
           python -m pip install mypy pytest-cov -r requirements.txt
       # FIXME: #4052 fix mypy errors in the exclude directories and remove them below
       - run: mypy --ignore-missing-imports
-          --exclude '(ciphers|conversions|data_structures|digital_image_processing|dynamic_programming|graphs|linear_algebra|maths|matrix|other|project_euler|scripts|searches|strings*)/$' .
+          --exclude '(conversions|data_structures|digital_image_processing|dynamic_programming|graphs|linear_algebra|maths|matrix|other|project_euler|scripts|searches|strings*)/$' .
       - name: Run tests
         run: pytest --doctest-modules --ignore=project_euler/ --ignore=scripts/ --cov-report=term-missing:skip-covered --cov=. .
       - if: ${{ success() }}

ciphers/diffie_hellman.py

@@ -241,9 +241,7 @@ def generate_shared_key(self, other_key_str: str) -> str:
         return sha256(str(shared_key).encode()).hexdigest()
 
     @staticmethod
-    def is_valid_public_key_static(
-        local_private_key_str: str, remote_public_key_str: str, prime: int
-    ) -> bool:
+    def is_valid_public_key_static(remote_public_key_str: int, prime: int) -> bool:
         # check if the other public key is valid based on NIST SP800-56
         if 2 <= remote_public_key_str and remote_public_key_str <= prime - 2:
             if pow(remote_public_key_str, (prime - 1) // 2, prime) == 1:
@@ -257,9 +255,7 @@ def generate_shared_key_static(
         local_private_key = int(local_private_key_str, base=16)
         remote_public_key = int(remote_public_key_str, base=16)
         prime = primes[group]["prime"]
-        if not DiffieHellman.is_valid_public_key_static(
-            local_private_key, remote_public_key, prime
-        ):
+        if not DiffieHellman.is_valid_public_key_static(remote_public_key, prime):
             raise ValueError("Invalid public key")
         shared_key = pow(remote_public_key, local_private_key, prime)
         return sha256(str(shared_key).encode()).hexdigest()

ciphers/hill_cipher.py

@@ -64,13 +64,12 @@ class HillCipher:
 
     to_int = numpy.vectorize(lambda x: round(x))
 
-    def __init__(self, encrypt_key: int):
+    def __init__(self, encrypt_key: numpy.ndarray) -> None:
         """
         encrypt_key is an NxN numpy array
         """
         self.encrypt_key = self.modulus(encrypt_key)  # mod36 calc's on the encrypt key
         self.check_determinant()  # validate the determinant of the encryption key
-        self.decrypt_key = None
         self.break_key = encrypt_key.shape[0]
 
     def replace_letters(self, letter: str) -> int:
@@ -139,8 +138,8 @@ def encrypt(self, text: str) -> str:
 
         for i in range(0, len(text) - self.break_key + 1, self.break_key):
             batch = text[i : i + self.break_key]
-            batch_vec = [self.replace_letters(char) for char in batch]
-            batch_vec = numpy.array([batch_vec]).T
+            vec = [self.replace_letters(char) for char in batch]
+            batch_vec = numpy.array([vec]).T
             batch_encrypted = self.modulus(self.encrypt_key.dot(batch_vec)).T.tolist()[
                 0
             ]
@@ -151,7 +150,7 @@ def encrypt(self, text: str) -> str:
 
         return encrypted
 
-    def make_decrypt_key(self):
+    def make_decrypt_key(self) -> numpy.ndarray:
         """
         >>> hill_cipher = HillCipher(numpy.array([[2, 5], [1, 6]]))
         >>> hill_cipher.make_decrypt_key()
@@ -184,17 +183,15 @@ def decrypt(self, text: str) -> str:
         >>> hill_cipher.decrypt('85FF00')
         'HELLOO'
         """
-        self.decrypt_key = self.make_decrypt_key()
+        decrypt_key = self.make_decrypt_key()
         text = self.process_text(text.upper())
         decrypted = ""
 
         for i in range(0, len(text) - self.break_key + 1, self.break_key):
             batch = text[i : i + self.break_key]
-            batch_vec = [self.replace_letters(char) for char in batch]
-            batch_vec = numpy.array([batch_vec]).T
-            batch_decrypted = self.modulus(self.decrypt_key.dot(batch_vec)).T.tolist()[
-                0
-            ]
+            vec = [self.replace_letters(char) for char in batch]
+            batch_vec = numpy.array([vec]).T
+            batch_decrypted = self.modulus(decrypt_key.dot(batch_vec)).T.tolist()[0]
             decrypted_batch = "".join(
                 self.replace_digits(num) for num in batch_decrypted
             )
@@ -203,12 +200,12 @@ def decrypt(self, text: str) -> str:
         return decrypted
 
 
-def main():
+def main() -> None:
     N = int(input("Enter the order of the encryption key: "))
     hill_matrix = []
 
     print("Enter each row of the encryption key with space separated integers")
-    for i in range(N):
+    for _ in range(N):
         row = [int(x) for x in input().split()]
         hill_matrix.append(row)
 

ciphers/mixed_keyword_cypher.py

@@ -29,32 +29,32 @@ def mixed_keyword(key: str = "college", pt: str = "UNIVERSITY") -> str:
     # print(temp)
     alpha = []
     modalpha = []
-    for i in range(65, 91):
-        t = chr(i)
+    for j in range(65, 91):
+        t = chr(j)
         alpha.append(t)
         if t not in temp:
             temp.append(t)
     # print(temp)
     r = int(26 / 4)
     # print(r)
     k = 0
-    for i in range(r):
-        t = []
+    for _ in range(r):
+        s = []
         for j in range(len_temp):
-            t.append(temp[k])
+            s.append(temp[k])
             if not (k < 25):
                 break
             k += 1
-        modalpha.append(t)
+        modalpha.append(s)
     # print(modalpha)
     d = {}
     j = 0
     k = 0
     for j in range(len_temp):
-        for i in modalpha:
-            if not (len(i) - 1 >= j):
+        for m in modalpha:
+            if not (len(m) - 1 >= j):
                 break
-            d[alpha[k]] = i[j]
+            d[alpha[k]] = m[j]
             if not k < 25:
                 break
             k += 1

ciphers/mono_alphabetic_ciphers.py

@@ -1,7 +1,11 @@
+from typing import Literal
+
 LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 
 
-def translate_message(key, message, mode):
+def translate_message(
+    key: str, message: str, mode: Literal["encrypt", "decrypt"]
+) -> str:
     """
     >>> translate_message("QWERTYUIOPASDFGHJKLZXCVBNM","Hello World","encrypt")
     'Pcssi Bidsm'
@@ -40,7 +44,7 @@ def decrypt_message(key: str, message: str) -> str:
     return translate_message(key, message, "decrypt")
 
 
-def main():
+def main() -> None:
     message = "Hello World"
     key = "QWERTYUIOPASDFGHJKLZXCVBNM"
     mode = "decrypt"  # set to 'encrypt' or 'decrypt'

ciphers/morse_code_implementation.py

@@ -83,7 +83,7 @@ def decrypt(message: str) -> str:
     return decipher
 
 
-def main():
+def main() -> None:
     message = "Morse code here"
     result = encrypt(message.upper())
     print(result)

ciphers/onepad_cipher.py

@@ -2,7 +2,8 @@
 
 
 class Onepad:
-    def encrypt(self, text: str) -> ([str], [int]):
+    @staticmethod
+    def encrypt(text: str) -> tuple[list[int], list[int]]:
         """Function to encrypt text using pseudo-random numbers"""
         plain = [ord(i) for i in text]
         key = []
@@ -14,14 +15,14 @@ def encrypt(self, text: str) -> ([str], [int]):
             key.append(k)
         return cipher, key
 
-    def decrypt(self, cipher: [str], key: [int]) -> str:
+    @staticmethod
+    def decrypt(cipher: list[int], key: list[int]) -> str:
         """Function to decrypt text using pseudo-random numbers."""
         plain = []
         for i in range(len(key)):
             p = int((cipher[i] - (key[i]) ** 2) / key[i])
             plain.append(chr(p))
-        plain = "".join([i for i in plain])
-        return plain
+        return "".join([i for i in plain])
 
 
 if __name__ == "__main__":

ciphers/playfair_cipher.py

@@ -1,8 +1,9 @@
 import itertools
 import string
+from typing import Generator, Iterable
 
 
-def chunker(seq, size):
+def chunker(seq: Iterable[str], size: int) -> Generator[tuple[str, ...], None, None]:
     it = iter(seq)
     while True:
         chunk = tuple(itertools.islice(it, size))
@@ -37,7 +38,7 @@ def prepare_input(dirty: str) -> str:
     return clean
 
 
-def generate_table(key: str) -> [str]:
+def generate_table(key: str) -> list[str]:
 
     # I and J are used interchangeably to allow
     # us to use a 5x5 table (25 letters)

ciphers/porta_cipher.py

@@ -28,7 +28,7 @@
 }
 
 
-def generate_table(key: str) -> [(str, str)]:
+def generate_table(key: str) -> list[tuple[str, str]]:
     """
     >>> generate_table('marvin')  # doctest: +NORMALIZE_WHITESPACE
     [('ABCDEFGHIJKLM', 'UVWXYZNOPQRST'), ('ABCDEFGHIJKLM', 'NOPQRSTUVWXYZ'),
@@ -60,30 +60,21 @@ def decrypt(key: str, words: str) -> str:
     return encrypt(key, words)
 
 
-def get_position(table: [(str, str)], char: str) -> (int, int) or (None, None):
+def get_position(table: tuple[str, str], char: str) -> tuple[int, int]:
     """
-    >>> table = [
-    ...     ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST'), ('ABCDEFGHIJKLM', 'NOPQRSTUVWXYZ'),
-    ...     ('ABCDEFGHIJKLM', 'STUVWXYZNOPQR'), ('ABCDEFGHIJKLM', 'QRSTUVWXYZNOP'),
-    ...     ('ABCDEFGHIJKLM', 'WXYZNOPQRSTUV'), ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST')]
-    >>> get_position(table, 'A')
-    (None, None)
+    >>> get_position(generate_table('marvin')[0], 'M')
+    (0, 12)
     """
-    if char in table[0]:
-        row = 0
-    else:
-        row = 1 if char in table[1] else -1
-    return (None, None) if row == -1 else (row, table[row].index(char))
+    # `char` is either in the 0th row or the 1st row
+    row = 0 if char in table[0] else 1
+    col = table[row].index(char)
+    return row, col
 
 
-def get_opponent(table: [(str, str)], char: str) -> str:
+def get_opponent(table: tuple[str, str], char: str) -> str:
     """
-    >>> table = [
-    ...     ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST'), ('ABCDEFGHIJKLM', 'NOPQRSTUVWXYZ'),
-    ...     ('ABCDEFGHIJKLM', 'STUVWXYZNOPQR'), ('ABCDEFGHIJKLM', 'QRSTUVWXYZNOP'),
-    ...     ('ABCDEFGHIJKLM', 'WXYZNOPQRSTUV'), ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST')]
-    >>> get_opponent(table, 'A')
-    'A'
+    >>> get_opponent(generate_table('marvin')[0], 'M')
+    'T'
     """
     row, col = get_position(table, char.upper())
     if row == 1:
@@ -97,14 +88,16 @@ def get_opponent(table: [(str, str)], char: str) -> str:
 
     doctest.testmod()  # Fist ensure that all our tests are passing...
     """
-    ENTER KEY: marvin
-    ENTER TEXT TO ENCRYPT: jessica
-    ENCRYPTED: QRACRWU
-    DECRYPTED WITH KEY: JESSICA
+    Demo:
+
+    Enter key: marvin
+    Enter text to encrypt: jessica
+    Encrypted: QRACRWU
+    Decrypted with key: JESSICA
     """
-    key = input("ENTER KEY: ").strip()
-    text = input("ENTER TEXT TO ENCRYPT: ").strip()
+    key = input("Enter key: ").strip()
+    text = input("Enter text to encrypt: ").strip()
     cipher_text = encrypt(key, text)
 
-    print(f"ENCRYPTED: {cipher_text}")
-    print(f"DECRYPTED WITH KEY: {decrypt(key, cipher_text)}")
+    print(f"Encrypted: {cipher_text}")
+    print(f"Decrypted with key: {decrypt(key, cipher_text)}")

ciphers/rail_fence_cipher.py

@@ -20,7 +20,7 @@ def encrypt(input_string: str, key: int) -> str:
         ...
     TypeError: sequence item 0: expected str instance, int found
     """
-    grid = [[] for _ in range(key)]
+    temp_grid: list[list[str]] = [[] for _ in range(key)]
     lowest = key - 1
 
     if key <= 0:
@@ -31,8 +31,8 @@ def encrypt(input_string: str, key: int) -> str:
     for position, character in enumerate(input_string):
         num = position % (lowest * 2)  # puts it in bounds
         num = min(num, lowest * 2 - num)  # creates zigzag pattern
-        grid[num].append(character)
-    grid = ["".join(row) for row in grid]
+        temp_grid[num].append(character)
+    grid = ["".join(row) for row in temp_grid]
     output_string = "".join(grid)
 
     return output_string
@@ -63,7 +63,7 @@ def decrypt(input_string: str, key: int) -> str:
     if key == 1:
         return input_string
 
-    temp_grid = [[] for _ in range(key)]  # generates template
+    temp_grid: list[list[str]] = [[] for _ in range(key)]  # generates template
     for position in range(len(input_string)):
         num = position % (lowest * 2)  # puts it in bounds
         num = min(num, lowest * 2 - num)  # creates zigzag pattern
@@ -84,7 +84,7 @@ def decrypt(input_string: str, key: int) -> str:
     return output_string
 
 
-def bruteforce(input_string: str) -> dict:
+def bruteforce(input_string: str) -> dict[int, str]:
     """Uses decrypt function by guessing every key
 
     >>> bruteforce("HWe olordll")[4]

ciphers/rot13.py

@@ -20,7 +20,7 @@ def dencrypt(s: str, n: int = 13) -> str:
     return out
 
 
-def main():
+def main() -> None:
     s0 = input("Enter message: ")
 
     s1 = dencrypt(s0, 13)