diff --git a/chapter_three/Lineares-Schieberegister.py b/chapter_three/Lineares-Schieberegister.py
index 6acb1f2..d212828 100644
--- a/chapter_three/Lineares-Schieberegister.py
+++ b/chapter_three/Lineares-Schieberegister.py
@@ -5,7 +5,15 @@ INIT_STATE = [0, 1, 1, 0]
 COEFFICIENTS = [1, 1, 1, 0]
 
 
-def create_shift_register(init_state: list, coefficients: list):
+def create_shift_register(init_state: [int], coefficients: [int]) -> [int]:
+    """
+    Creates and returns the maximum bit stream for the given input state via a linear shift register.
+    Especially the coefficients are important as choosing the correct ones for any given shift register length
+    will provide the maximum amount of bits before they repeat
+    :param init_state: The initial bits in the shift register
+    :param coefficients: The coefficients of every field in the shift register
+    :return: The maximum length bit stream generated by the linear shift register
+    """
     return_list = []
     current_state = init_state.copy()
     current_state_list = [current_state.copy()]
diff --git a/utils/CipherUtils.py b/utils/CipherUtils.py
index 2671530..bebc63e 100644
--- a/utils/CipherUtils.py
+++ b/utils/CipherUtils.py
@@ -93,7 +93,15 @@ def shift_char(char, incrementation: int = 1):
     return str(new_char_in_bytes)[2]
 
 
-def xor_two_lists(clear_list, key_list):
+def xor_two_lists(clear_list: [int], key_list: [int]) -> [int]:
+    """
+    XORs every element of the first given list with the corresponding element of the 2nd list.
+    If the 2nd list is shorter than the first one, the XORing starts at the first element of the
+    2nd list again once all elements have been used and so on.
+    :param clear_list: The first list
+    :param key_list: The second list. This list may be shorter or longer than the first one, doesn't matter
+    :return: A list containing the XORed elements.
+    """
     xored_list = []
 
     for x in range(len(clear_list)):