✨ Added Lineares Schieberegister

- no comments

chapter_three/Lineares-Schieberegister.py

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+from utils import CipherUtils
+
+CLEAR_LIST = [0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1]
+INIT_STATE = [0, 1, 1, 0]
+COEFFICIENTS = [1, 1, 1, 0]
+
+
+def create_shift_register(init_state: list, coefficients: list):
+    return_list = []
+    current_state = init_state.copy()
+    current_state_list = [current_state.copy()]
+
+    if (size := len(init_state)) != len(coefficients):
+        print('Length of lists does not match.')
+        exit()
+
+    for x in range(2 ** size):
+        return_list.append(current_state[-1])
+        new_state_value = 0
+        for i in range(size):
+            new_state_value = (new_state_value + current_state[i] ^ coefficients[i]) % 2
+
+        current_state.insert(0, new_state_value)
+        current_state.pop(-1)
+
+        if current_state in current_state_list:
+            return_list.extend(current_state[1:][::-1])
+            break
+        current_state_list.append(current_state.copy())
+
+    return return_list
+
+
+if __name__ == '__main__':
+    key = create_shift_register(INIT_STATE, COEFFICIENTS)
+
+    encrypted = CipherUtils.xor_two_lists(CLEAR_LIST, key)
+    decrypted = CipherUtils.xor_two_lists(encrypted, key)
+    print(CLEAR_LIST)
+    print(encrypted)
+    print(decrypted)