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fixed decrypt_large_package

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Signed-off-by: dfirfpi <francesco.picasso@gmail.com>
This commit is contained in:
dfirfpi 2020-07-05 11:27:39 +02:00
parent 5c916ea2dd
commit 662574bb45
No known key found for this signature in database
GPG Key ID: EC61291E5446B028
1 changed files with 10 additions and 6 deletions
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16
kobackupdec.py
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@ -4,6 +4,7 @@
# Huawei KoBackup backups decryptor.
#
# Version History
# - 20200705: fixed decrypt_large_package to read input's chunks
# - 20200611: added 'expandtar' option, to avoid automatic expansion of TARs
# added 'writable' option, to allow user RW on decrypted files
# large TAR files are not managed in chunk but not expanded
@ -60,7 +61,7 @@ from Crypto.Hash import HMAC
from Crypto.Protocol.KDF import PBKDF2
from Crypto.Util import Counter
VERSION = '20200611'
VERSION = '20200705'
# Disabling check on doc strings and naming convention.
# pylint: disable=C0111,C0103
@ -316,7 +317,7 @@ class Decryptor:
decryptor = AES.new(key, mode=AES.MODE_CTR, counter=counter_obj)
return decryptor.decrypt(data)
def decrypt_large_package(self, dec_material, data):
def decrypt_large_package(self, dec_material, entry):
if not self._good:
logging.warning('well, it is hard to decrypt with a wrong key.')
@ -334,9 +335,12 @@ class Decryptor:
counter_iv, byteorder='big'), little_endian=False)
decryptor = AES.new(key, mode=AES.MODE_CTR, counter=counter_obj)
data_view = memoryview(data)
for x in range(0, len(data), self.chunk_size):
yield decryptor.decrypt(data_view[x:x+self.chunk_size])
data_len = entry.stat().st_size
with open(entry, 'rb') as entry_fd:
for x in range(0, data_len, self.chunk_size):
logging.debug('decrypting chunk %d of %s', x, entry)
data = entry_fd.read(self.chunk_size)
yield decryptor.decrypt(data)
def decrypt_file(self, dec_material, data):
if not self._good:
@ -696,7 +700,7 @@ def decrypt_large_entry(decrypt_info, entry, type_info, search=False):
search)
if decrypt_material:
for x in decrypt_info.decryptor.decrypt_large_package(
decrypt_material, entry.read_bytes()):
decrypt_material, entry):
yield x
else:
logging.warning('entry %s has no decrypt material!', skey)