From 974d62343b80de4a818edaf936392b3868054b52 Mon Sep 17 00:00:00 2001
From: localhorst <localhorst@mosad.xyz>
Date: Sat, 16 Oct 2021 23:18:10 +0200
Subject: [PATCH] initial

---
 eeprom_dump_modifier.py | 112 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 eeprom_dump_modifier.py

diff --git a/eeprom_dump_modifier.py b/eeprom_dump_modifier.py
new file mode 100644
index 0000000..06a2a72
--- /dev/null
+++ b/eeprom_dump_modifier.py
@@ -0,0 +1,112 @@
+ 
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+""" Author:                     Hendrik Schutter, mail@hendrikschutter.com
+    Date of creation:           2021/10/16
+    Date of last modification:  2021/10/16
+
+"""
+import hashlib
+
+old_entry_secure_boot_str = "AA553F0003000000000000000000000000000000000000000000000000000000000000002200000001000000C70BA3F008AF564599C4001009C93A4453006500630075007200650042006F006F00740045006E00610062006C006500000001"
+new_entry_secure_boot_str = "AA55000003000000000000000000000000000000000000000000000000000000000000002200000001000000C70BA3F008AF564599C4001009C93A4453006500630075007200650042006F006F00740045006E00610062006C006500000001"
+
+old_eeprom_dump = "with_SecBoot.bin"
+new_eeprom_dump = "with_SecBoot_modified.bin"
+
+#old_eeprom_dump = "test.bin"
+#new_eeprom_dump = "test_modified.bin"
+
+old_entry_secure_boot_bytes = [old_entry_secure_boot_str.lower()[i:i+2] for i in range(0, len(old_entry_secure_boot_str.lower()), 2)]
+new_entry_secure_boot_bytes = [new_entry_secure_boot_str.lower()[i:i+2] for i in range(0, len(new_entry_secure_boot_str.lower()), 2)]
+
+def show_file_stats():
+    print(" === old eeprom dump ===")
+    tmp_file = open(old_eeprom_dump, 'rb')
+    hash = str(hashlib.sha256(tmp_file.read()).hexdigest())
+    tmp_file.seek(0,2)
+    print("Size: " + str(tmp_file.tell()))
+    print("Hash: " + hash)
+    tmp_file.close()
+
+    try:
+        tmp_file = open(new_eeprom_dump, 'rb')
+        hash = str(hashlib.sha256(tmp_file.read()).hexdigest())
+        print("\n ===new eeprom dump === ")
+        tmp_file.seek(0,2)
+        print("Size: " + str(tmp_file.tell()))
+        print("Hash: " + hash)
+    except IOError:
+        pass
+    finally:
+        tmp_file.close()
+
+def get_pattern_offset(data):
+    pattern_start_index = -1
+    byte_index = 0
+    for byte in data:
+        if(byte.hex() == old_entry_secure_boot_bytes[0]):
+            if pattern_start_index == -1:
+                pattern_start_index = byte_index
+                for x in range(pattern_start_index, pattern_start_index+len(old_entry_secure_boot_bytes)): 
+                    if(data[x].hex() != old_entry_secure_boot_bytes[(x-pattern_start_index)]):
+                        pattern_start_index = -1
+                        break
+        byte_index += 1
+    return pattern_start_index
+
+
+def replace_data(data, replacement, offset):
+    for x in range(offset, offset+len(replacement)): 
+        data[x] = bytes.fromhex(replacement[x-offset])
+
+def edit_data(data, new_eeprom_dump_file):
+    offset = get_pattern_offset(data)
+    
+    if offset != -1:
+        print("Pattern offset: " + str(offset)) 
+        
+        replace_data(data, new_entry_secure_boot_bytes, offset)
+        
+        for byte in data:
+            #print(byte.hex())
+            new_eeprom_dump_file.write(byte)
+        new_eeprom_dump_file.flush()
+    else:
+        print("unable to find pattern")
+    
+def main():
+    print("start ...\n")
+    
+    if(len(old_entry_secure_boot_str) != len(new_entry_secure_boot_str)):
+        print("entries are not the same sizes")
+        return
+    
+    old_eeprom_dump_file = open(old_eeprom_dump, "rb")
+    new_eeprom_dump_file = open(new_eeprom_dump, "wb")
+    
+    old_eeprom_dump_data = []
+    
+    byte = old_eeprom_dump_file.read(1)
+    while byte:
+        old_eeprom_dump_data.append(byte)
+        byte = old_eeprom_dump_file.read(1)
+        
+    edit_data(old_eeprom_dump_data, new_eeprom_dump_file)
+        
+    #time.sleep(100)
+    show_file_stats()
+    
+if __name__ == "__main__":
+    main()
+
+
+
+
+
+
+
+
+
+