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it turns out some of those bits weren't random

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beerpsi 2024-07-18 03:12:57 +07:00
parent 2f654ec64f
commit fce4269fc9
1 changed files with 20 additions and 5 deletions
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25
segafs/makesegafs.py
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@ -1,11 +1,14 @@
# pyright: reportMissingTypeStubs=false, reportOperatorIssue=false, reportUnknownArgumentType=false, reportUnknownMemberType=false
from math import ceil from math import ceil
import os import os
import secrets import secrets
import struct import struct
import time
import zlib import zlib
from Crypto.Cipher import AES from Crypto.Cipher import AES, PKCS1_OAEP
from Crypto.Hash import HMAC, SHA1 from Crypto.Hash import HMAC, SHA1
from Crypto.PublicKey import RSA
from construct import Bytes, Const, Int16ul, Int32ul, Int64ul, Int8ul, Struct from construct import Bytes, Const, Int16ul, Int32ul, Int64ul, Int8ul, Struct
# ---- Configuration # ---- Configuration
@ -65,6 +68,17 @@ BTIV = bytes.fromhex("")
# The HMAC key that ensures the app/opt/pack created is authentic. # The HMAC key that ensures the app/opt/pack created is authentic.
SIGKEY = bytes.fromhex("") SIGKEY = bytes.fromhex("")
HEADER_META_PUBKEY = RSA.import_key("""-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsRMLnJuczNpfoqPpHQ3o
5XNkjKXO6P3ToV/45Az5dNaHVL7uEu9vPI7a2KYFQnNYgD3UUHFahfTcljzLOkcH
1aVrhm8gaB/5mygjUJWcN+kKyB7sASqhL22RC7NlxtDY15ozli/b0MagVoaBAV5D
MytUCa73GPRGY0x9v/wTvtmFclYCWjJ9c2QzrCrQ9eNTVyETwh5q6qKEARHGZgCX
rWmdCsa/+oS+3pLbUGFlHCSZtCvvWCJgmgurlTGAGzoxrieO6XDEg2AGiRprWWL2
BGNh7gwgnSq6FWnKSf2Qe7xoFcTpV5QhNFBQjrq0KnBDRfz5EXJnMoKxNYL6reqR
uwIDAQAB
-----END PUBLIC KEY-----
""")
# ---- # ----
# ---- Constants. Don't edit. # ---- Constants. Don't edit.
@ -123,8 +137,10 @@ print(f"Generated IV: {iv.hex()}")
filesize = os.stat(INPUT_FILE).st_size filesize = os.stat(INPUT_FILE).st_size
BOOTID["block_count"] = ceil(filesize / BOOTID["block_size"]) + 8 BOOTID["block_count"] = ceil(filesize / BOOTID["block_size"]) + 8
bullshit = secrets.token_bytes(BOOTID["block_size"]) header_meta = struct.pack("<Q", time.time()) + os.path.abspath(INPUT_FILE).encode("utf-8")
bullshit_crc32 = zlib.crc32(bullshit) header_meta += secrets.token_bytes(BOOTID["block_size"] - len(header_meta))
header_meta = PKCS1_OAEP.new(HEADER_META_PUBKEY).encrypt(header_meta)
bullshit_crc32 = zlib.crc32(header_meta)
block_crc32s = [0, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32] block_crc32s = [0, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32, bullshit_crc32]
with open(INPUT_FILE, "rb") as fin, open(OUTPUT_FILE, "w+b") as fout: with open(INPUT_FILE, "rb") as fin, open(OUTPUT_FILE, "w+b") as fout:
@ -140,9 +156,8 @@ with open(INPUT_FILE, "rb") as fin, open(OUTPUT_FILE, "w+b") as fout:
# We'll generate random bytes for them though. # We'll generate random bytes for them though.
_ = fout.write(secrets.token_bytes(BOOTID["block_size"] - 0x2800)) _ = fout.write(secrets.token_bytes(BOOTID["block_size"] - 0x2800))
# Bullshit out 7 random blocks for the header.
for i in range(BOOTID["header_block_count"] - 1): for i in range(BOOTID["header_block_count"] - 1):
_ = fout.write(bullshit) _ = fout.write(header_meta)
# Encrypt the contents of the file. # Encrypt the contents of the file.
total_written = 0 total_written = 0