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makesegafs
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beerpsi
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2f654ec64f
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Miscellaneous scripts that don't need their own repo.
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## `app`/`opt`/`pack`
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- `segafs/makesegafs.py`: Create an `app`/`opt`/`pack` (same thing) from an unencrypted
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disk image.
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- Dependencies: `pip install construct PyCryptodome`
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- You will need to find the BootID key/IV and the HMAC key yourself if you want to
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make fake apps for whatever reason. Or just don't.
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## Patchers
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- `patchers/b2spatch.mjs`: Convert from BemaniPatcher to Spice2x JSON
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- Requires `cheerio`: `npm i cheerio`
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218
segafs/makesegafs.py
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218
segafs/makesegafs.py
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from math import ceil
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import os
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import secrets
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import struct
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import zlib
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from Crypto.Cipher import AES
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from Crypto.Hash import HMAC, SHA1
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from construct import Bytes, Const, Int16ul, Int32ul, Int64ul, Int8ul, Struct
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# ---- Configuration
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ENCRYPTION_KEY = bytes.fromhex("")
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INPUT_FILE = "" # Should not be encrypted.
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OUTPUT_FILE = ""
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BOOTID = {
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"type": 0x0201, # 0x0201: Option, 0x0000: Pack, 0x0101: App
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"sequence_number": 0x0000, # Set to 256 (0x0100) for options.
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"game_id": b"SDGS",
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"game_timestamp": {
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"year": 2023,
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"month": 12,
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"day": 28,
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"hour": 16,
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"minute": 34,
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"second": 43,
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"milli": 0,
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},
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"game_version": {
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"release": 0,
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"minor": 30,
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"major": 1,
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},
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"block_size": 0x40000,
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"header_block_count": 8,
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"unk1": 0,
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"hw_family": b"ACA",
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"hw_generation": 0,
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"org_timestamp": {
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"year": 0,
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"month": 0,
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"day": 0,
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"hour": 0,
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"minute": 0,
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"second": 0,
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"milli": 0,
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},
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"org_version": {
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"release": 0,
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"minor": 0,
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"major": 0,
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},
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"os_version": {
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"release": 1,
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"minor": 54,
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"major": 80,
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},
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"strings": b"\x00" * 0x27AC, # Depending on the app/opt/pack, this might have some text in it.
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}
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# ----
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# ---- Keys
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# The BootID (app/opt/pack header) encryption key and IV.
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BTKEY = bytes.fromhex("")
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BTIV = bytes.fromhex("")
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# The HMAC key that ensures the app/opt/pack created is authentic.
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SIGKEY = bytes.fromhex("")
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# ----
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# ---- Constants. Don't edit.
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EXFAT_HEADER = bytes.fromhex("EB769045584641542020200000000000")
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OPTION_IV = bytes.fromhex("C063BF6F562D084D7963C987F5281761")
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# ----
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# ---- Script
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Timestamp = Struct(
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"year" / Int16ul,
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"month" / Int8ul,
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"day" / Int8ul,
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"hour" / Int8ul,
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"minute" / Int8ul,
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"second" / Int8ul,
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"milli" / Int8ul,
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)
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Version = Struct(
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"release" / Int8ul,
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"minor" / Int8ul,
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"major" / Int16ul,
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)
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BootID = Struct(
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"length" / Const(0x2800, Int32ul),
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"magic" / Const(b"BTID", Bytes(4)),
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"type" / Int16ul,
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"sequence_number" / Int16ul,
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"game_id" / Bytes(4),
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"game_timestamp" / Timestamp,
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"game_version" / Version,
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"block_count" / Int64ul,
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"block_size" / Int64ul,
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"header_block_count" / Int64ul,
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"unk1" / Int64ul,
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"hw_family" / Bytes(3),
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"hw_generation" / Int8ul,
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"org_timestamp" / Timestamp,
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"org_version" / Version,
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"os_version" / Version,
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"strings" / Bytes(0x27AC),
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)
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def get_page_iv(iv: bytes, offset: int):
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return bytes(x ^ (offset >> (8 * (i % 8))) & 0xFF for (i, x) in enumerate(iv))
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iv = secrets.token_bytes(16)
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if BOOTID["type"] == 0x0201:
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iv = bytes(x ^ EXFAT_HEADER[i] ^ OPTION_IV[i] for (i, x) in enumerate(iv))
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print(f"Generated IV: {iv.hex()}")
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filesize = os.stat(INPUT_FILE).st_size
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BOOTID["block_count"] = ceil(filesize / BOOTID["block_size"]) + 8
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bullshit = secrets.token_bytes(BOOTID["block_size"])
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bullshit_crc32 = zlib.crc32(bullshit)
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block_crc32s = [0, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32]
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with open(INPUT_FILE, "rb") as fin, open(OUTPUT_FILE, "w+b") as fout:
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# Write the bootID.
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cipher = AES.new(BTKEY, AES.MODE_CBC, BTIV)
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bootid = BootID.build(BOOTID)
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bootid_crc32 = zlib.crc32(bootid)
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bootid_bytes = cipher.encrypt(struct.pack("<I", bootid_crc32) + bootid)
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_ = fout.write(bootid_bytes)
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# Ignore the CRC32s and the signature for now, we'll come back later.
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# We'll generate random bytes for them though.
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_ = fout.write(secrets.token_bytes(BOOTID["block_size"] - 0x2800))
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# Bullshit out 7 random blocks for the header.
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for i in range(BOOTID["header_block_count"] - 1):
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_ = fout.write(bullshit)
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# Encrypt the contents of the file.
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total_written = 0
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to_read = filesize
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block_crc32 = 0
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while to_read > 0:
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page_iv = get_page_iv(iv, total_written)
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contents = fin.read(4096)
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contents_len = len(contents)
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to_read -= contents_len
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if contents_len < 4096:
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contents += b"\x00" * (4096 - contents_len)
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cipher = AES.new(ENCRYPTION_KEY, AES.MODE_CBC, page_iv)
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encrypted = cipher.encrypt(contents)
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total_written += fout.write(encrypted)
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block_crc32 = zlib.crc32(encrypted, block_crc32)
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if (total_written % BOOTID["block_size"]) == 0:
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block_crc32s.append(block_crc32)
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block_crc32 = 0
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# Pad with null bytes if we have an unfinished block.
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if (total_written % BOOTID["block_size"]) != 0:
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null_byte_count = BOOTID["block_size"] - (total_written % BOOTID["block_size"])
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while null_byte_count > 0:
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page_iv = get_page_iv(iv, total_written)
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cipher = AES.new(ENCRYPTION_KEY, AES.MODE_CBC, page_iv)
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encrypted = cipher.encrypt(b"\x00" * 4096)
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total_written += fout.write(encrypted)
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block_crc32 = zlib.crc32(encrypted, block_crc32)
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null_byte_count -= 4096
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block_crc32s.append(block_crc32)
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block_crc32 = 0
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# We can finally revisit the CRC32s.
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_ = fout.seek(0x2A04)
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for crc32 in block_crc32s[1:]:
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_ = fout.write(struct.pack("<I", crc32))
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_ = fout.seek(0)
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block_0_crc32 = zlib.crc32(fout.read(0x2800))
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# Skip the HMAC signature and the first CRC32, which we're trying to calculate.
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_ = fout.seek(0x204, os.SEEK_CUR)
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block_0_crc32 = zlib.crc32(fout.read(BOOTID["block_size"] - 0x2800 - 0x204), block_0_crc32)
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_ = fout.seek(0x2A00)
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_ = fout.write(struct.pack("<I", block_0_crc32))
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# Calculate the HMAC signature.
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_ = fout.seek(0x2A00)
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hmac = HMAC.new(SIGKEY, digestmod=SHA1)
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to_read = BOOTID["block_size"] * 8 - 0x2A00
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while to_read > 0:
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block = fout.read(min(0x1000, to_read))
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if len(block) == 0:
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raise Exception("Ran out of data making the signature.")
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_ = hmac.update(block)
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to_read -= len(block)
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_ = fout.seek(0x2800)
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_ = fout.write(hmac.digest())
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