create beaufort cipher

ciphers/beaufort_cipher.py

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+"""
+Author: Mohit Radadiya
+"""
+
+from string import ascii_uppercase
+
+dict1 = {char: i for i, char in enumerate(ascii_uppercase)}
+dict2 = {i: char for i, char in enumerate(ascii_uppercase)}
+
+
+# This function generates the key in
+# a cyclic manner until it's length isn't
+# equal to the length of original text
+def generate_key(message: str, key: str) -> str:
+    """
+    >>> generate_key("THE GERMAN ATTACK","SECRET")
+    'SECRETSECRETSECRE'
+    """
+    x = len(message)
+    i = 0
+    while True:
+        if x == i:
+            i = 0
+        if len(key) == len(message):
+            break
+        key += key[i]
+        i += 1
+    return key
+
+
+# This function returns the encrypted text
+# generated with the help of the key
+def cipher_text(message: str, key_new: str) -> str:
+    """
+    >>> cipher_text("THE GERMAN ATTACK","SECRETSECRETSECRE")
+    'BDC PAYUWL JPAIYI'
+    """
+    cipher_text = ""
+    i = 0
+    for letter in message:
+        if letter == " ":
+            cipher_text += " "
+        else:
+            x = (dict1[letter] - dict1[key_new[i]]) % 26
+            i += 1
+            cipher_text += dict2[x]
+    return cipher_text
+
+
+# This function decrypts the encrypted text
+# and returns the original text
+def original_text(cipher_text: str, key_new: str) -> str:
+    """
+    >>> original_text("BDC PAYUWL JPAIYI","SECRETSECRETSECRE")
+    'THE GERMAN ATTACK'
+    """
+    or_txt = ""
+    i = 0
+    for letter in cipher_text:
+        if letter == " ":
+            or_txt += " "
+        else:
+            x = (dict1[letter] + dict1[key_new[i]] + 26) % 26
+            i += 1
+            or_txt += dict2[x]
+    return or_txt
+
+
+def main():
+    message = "THE GERMAN ATTACK"
+    key = "SECRET"
+    key_new = generate_key(message, key)
+    s = cipher_text(message, key_new)
+    print(f"Encrypted Text = {s}")
+    print(f"Original Text = {original_text(s, key_new)}")
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+    main()