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Physical Store Private Key Derivation

Background

As described in the TSforge blogpost, the AES key needed to decrypt the physical store's contents is encrypted using an RSA whitebox located in a component known as the blackbox/secure processor (spsys.sys on Windows Vista/7, part of sppsvc.exe on Windows 8+). Luckily, with a debugger and a basic understanding of the math behind RSA, the private key of this whitebox can be easily extracted, allowing exploits like ZeroCID to be carried out on an unmodified system.

SpModExpPrv

In the symbols for spsys.sys in Windows 8 build 7850, the whitebox is named SpModExpPrv. This function only implements plain RSA decryption with a constant private key, and other code is used to implement operations such as padding and RSA encryption.

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S Mode Escape

Requirements

• Access to Administrator-level account
• Does not require MS account
• Does not require disabling secure boot

How to Use

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Emulate iOS on Linux

This is a set of notes, meant to serve as a companion to the primary instruction set.

Companion VM

Use Arch Boxes basic images for the VM.

For installing dependencies, you can use AUR to install usbmuxd-git and libirecovery-git, then manually build patched idevicerestore.

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>AppExtensions</key>
	<dict>
		<key>/private/var/staged_system_apps/Shortcuts.app/PlugIns/RunShortcut.appex</key>
		<dict>
			<key>_executablePath</key>
			<string>/private/var/staged_system_apps/Shortcuts.app/PlugIns/RunShortcut.appex/RunShortcut</string>

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from Crypto.Cipher import ARC4
from hashlib import sha1, md5
from random import randint
from ecutils.core import Point, EllipticCurve
from sys import argv

KCHARS = "BCDFGHJKMPQRTVWXY2346789"

SPK_ECKEY = {
    "a": 1,

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import hashlib

def add_pid_cksum(pid):
    sumPID = 0
    val = pid
    
    while val != 0:
        sumPID += val % 10
        val //= 10
    

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from struct import pack, unpack, calcsize
from json import dumps
from os.path import basename
import sys

def readint(f):
    return unpack("<I", f.read(4))[0]

def readstc(f, s):
    s = "<" + s

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import re
from glob import glob
from subprocess import run, PIPE
from os.path import basename
from os import remove
from shutil import rmtree

def text_scan(text, pattern, flags=0):
    return re.findall(pattern, text, re.MULTILINE | re.IGNORECASE)