investigative reversing 1/2

investigative_reversing_2/sol.py

@@ -0,0 +1,19 @@
+#!/home/maxime/.pyvenv/bin/python3
+
+with open("encoded.bmp", 'rb') as f:
+    img = f.read()
+    flag_len = 50
+    stego_len = flag_len * 8
+    stego_start = 2000
+    encoded_bytes = img[stego_start:stego_start + stego_len]
+
+    flag_buffer = [''] * flag_len
+    for i, flag_char in enumerate(flag_buffer):
+        char = 0
+        for j in range(8):
+            img_char = encoded_bytes[i*8+j]
+            char |= (img_char & 1) << j
+        flag_buffer[i] = chr(char + 5)
+
+print(''.join(flag_buffer))
+