Added diffusion and confusion

1 files changed, 105 insertions, 17 deletions

diff --git a/main.py b/main.py
index ac8d267..3882f29 100644
--- a/main.py
+++ b/main.py
@@ -9,29 +9,38 @@ matrix_size = 4
 
 
 def hex_to_matrix(hex_array):
+    """
+    Converts hex arrays to 4x4 matrices
+    :param hex_array: Array of 16 hex chars
+    :return: 4x4 matrix representation
+    """
     matrix = []
     for i in range(16):
         if i % matrix_size == 0:
             matrix.append([hex_array[i]])
         else:
-            matrix[int(i / 4)].append(hex_array[i])
+            matrix[int(i / matrix_size)].append(hex_array[i])
     return matrix
 
 
 def text_to_hex(text):
+    """
+    Converts text to a array-hex representation
+    :param text: String/ASCII/UNICODE text
+    :return: Array of hex chars
+    """
     hex_array = []
     for char in text:
         hex_array.append(ord(char))
     return hex_array
 
 
-def shift_matrix(matrix):
-    for i in range(matrix_size):
-        matrix[i] = matrix[i][-i:] + matrix[i][:-i]
-    return matrix
-
-
 def key_expansion(key_matrix):
+    """
+    Expands a single key matrix to 11 distinct ones
+    :param key_matrix: Matrix of master passphrase
+    :return: Array of 11 round keys
+    """
     round_keys = [key_matrix]
     round_key = key_matrix[:]
     for r in range(0, 10):
@@ -47,14 +56,13 @@ def key_expansion(key_matrix):
     return round_keys
 
 
-def xor_matrix(first, second):
-    first = first.copy()
-    for i in range(4):
-        first[i] = first[i] ^ second[i]
-    return first
-
-
 def round_last(round_key, r):
+    """
+    Applies special actions for bottom row
+    :param round_key: Complete matrix round key
+    :param r: Round index
+    :return: Modified bottom row (last column)
+    """
     # Shift bottom row
     last_column = round_key[1:] + round_key[:1]
 
@@ -67,9 +75,89 @@ def round_last(round_key, r):
     return last_column
 
 
+def encrypt(text, passphrase):
+    """
+    Encrypts a text using a 128-Bit passphrase
+    :param text: Plain text
+    :param passphrase: 128-Bit passphrase (16 chars)
+    :return: Encrypted text
+    """
+    key_matrix = hex_to_matrix(text_to_hex(passphrase))
+    text_matrix = hex_to_matrix(text_to_hex(text))
+    round_keys = key_expansion(key_matrix)
+    merged_matrix = xor_matrices(key_matrix, text_matrix)
+    # 9 intermediate rounds for 128 Bit key size
+    for i in range(1):
+        confused_matrix = confusion(merged_matrix)
+        diffused_matrix = diffusion(confused_matrix)
+        mixed_matrix = mix_columns(diffused_matrix)
+        merged_matrix = xor_matrices(merged_matrix, mixed_matrix)
+
+
+def confusion(merged_matrix):
+    """
+    Applies confusion by running bytes through sbox
+    :param merged_matrix: Merged matrix of key and text
+    :return: New "confused" matrix
+    """
+    pprint(merged_matrix)
+    merged_matrix = merged_matrix.copy()
+    for i in range(matrix_size):
+        for j in range(matrix_size):
+            merged_matrix[i][j] = sbox[merged_matrix[i][j]]
+    pprint(merged_matrix)
+    return merged_matrix
+
+
+def diffusion(merged_matrix):
+    """
+    Shifts the merged matrix to the left
+    :param merged_matrix: Merged matrix of key and text
+    :return: New "diffused" matrix
+    """
+    merged_matrix = merged_matrix.copy()
+    for i in range(matrix_size):
+        merged_matrix[i] = merged_matrix[i][-i:] + merged_matrix[i][:-i]
+    pprint(merged_matrix)
+    return merged_matrix
+
+
+def mix_columns(merged_matrix):
+    """
+    Mixes columns with AES MixColumns algorithm
+    :param merged_matrix: Merged matrix of key and text
+    :return: New "mixed" matrix
+    """
+    return merged_matrix  # TODO
+
+
+def xor_matrix(first, second):
+    """
+    XORs 1-dimensional matrices
+    :param first: First matrix
+    :param second: Second matrix
+    :return: XORed (first) matrix
+    """
+    first = first.copy()
+    for i in range(4):
+        first[i] = first[i] ^ second[i]
+    return first
+
+
+def xor_matrices(first, second):
+    """
+    XORs 2-dimensional matrices
+    :param first: First matrix
+    :param second: Second matrix
+    :return: XORed (first) matrix
+    """
+    first = first.copy()
+    for i in range(len(first)):
+        first[i] = xor_matrix(first[i], second[i])
+    return first
+
+
 test_key = text_to_hex("Thats my Kung Fu")
 test_text = text_to_hex("Two One Nine Two")
 
-pprint(hex_to_matrix(test_key))
-print("\n\n")
-pprint(key_expansion(hex_to_matrix(test_key)))
+encrypt("ATTACK AT DAWN! ", "SOME 128 BIT KEY")