From dba8eecb47cea7f11ac383344524afbc0ca7cf5b Mon Sep 17 00:00:00 2001
From: Lonercode <91500485+Lonercode@users.noreply.github.com>
Date: Mon, 7 Oct 2024 10:58:07 +0100
Subject: [PATCH] added gronsfeld cipher implementation (#11835)

* added gronsfeld cipher implementation

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* from string import ascii_uppercase

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update gronsfeld_cipher.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
---
 ciphers/gronsfeld_cipher.py | 45 +++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 ciphers/gronsfeld_cipher.py

diff --git a/ciphers/gronsfeld_cipher.py b/ciphers/gronsfeld_cipher.py
new file mode 100644
index 000000000..8fbeab430
--- /dev/null
+++ b/ciphers/gronsfeld_cipher.py
@@ -0,0 +1,45 @@
+from string import ascii_uppercase
+
+
+def gronsfeld(text: str, key: str) -> str:
+    """
+    Encrypt plaintext with the Gronsfeld cipher
+
+    >>> gronsfeld('hello', '412')
+    'LFNPP'
+    >>> gronsfeld('hello', '123')
+    'IGOMQ'
+    >>> gronsfeld('', '123')
+    ''
+    >>> gronsfeld('yes, ¥€$ - _!@#%?', '0')
+    'YES, ¥€$ - _!@#%?'
+    >>> gronsfeld('yes, ¥€$ - _!@#%?', '01')
+    'YFS, ¥€$ - _!@#%?'
+    >>> gronsfeld('yes, ¥€$ - _!@#%?', '012')
+    'YFU, ¥€$ - _!@#%?'
+    >>> gronsfeld('yes, ¥€$ - _!@#%?', '')
+    Traceback (most recent call last):
+      ...
+    ZeroDivisionError: integer modulo by zero
+    """
+    ascii_len = len(ascii_uppercase)
+    key_len = len(key)
+    encrypted_text = ""
+    keys = [int(char) for char in key]
+    upper_case_text = text.upper()
+
+    for i, char in enumerate(upper_case_text):
+        if char in ascii_uppercase:
+            new_position = (ascii_uppercase.index(char) + keys[i % key_len]) % ascii_len
+            shifted_letter = ascii_uppercase[new_position]
+            encrypted_text += shifted_letter
+        else:
+            encrypted_text += char
+
+    return encrypted_text
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()