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89 lines
2.3 KiB
Python
89 lines
2.3 KiB
Python
"""Tarfile fileobject handler for encrypted files."""
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import tarfile
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import hashlib
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from Crypto.Cipher import AES
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from Crypto.Random import get_random_bytes
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from Crypto.Util.Padding import pad
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BLOCK_SIZE = 16
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MOD_READ = 'r'
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MOD_WRITE = 'w'
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class SecureTarFile(object):
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"""Handle encrypted files for tarfile library."""
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def __init__(self, name, mode, key=None, gzip=True):
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"""Initialize encryption handler."""
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self._file = None
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self._mode = mode
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self._name = name
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# Tarfile options
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self._tar = None
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self._tar_mode = f"{mode}|gz" if gzip else f"{mode}|"
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# Encryption/Decription
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self._aes = None
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self._key = key
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def __enter__(self):
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"""Start context manager tarfile."""
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if not self._key:
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self._tar = tarfile.open(name=str(self._name), mode=self._tar_mode)
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return self._tar
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# Encrypted/Decryped Tarfile
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self._file = self._name.open(f"{self._mode}b")
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# Extract IV for CBC
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if self._mode == MOD_READ:
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cbc_rand = self._file.read(16)
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else:
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cbc_rand = get_random_bytes(16)
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self._file.write(cbc_rand)
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self._aes = AES.new(
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self._key, AES.MODE_CBC, iv=_generate_iv(self._key, cbc_rand))
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self._tar = tarfile.open(fileobj=self, mode=self._tar_mode)
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return self._tar
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def __exit__(self, exc_type, exc_value, traceback):
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"""Close file."""
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if self._tar:
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self._tar.close()
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if self._file:
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self._file.close()
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def write(self, data):
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"""Write data."""
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if len(data) % BLOCK_SIZE != 0:
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data = pad(data, BLOCK_SIZE)
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self._file.write(self._aes.encrypt(data))
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def read(self, size=0):
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"""Read data."""
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return self._aes.decrypt(self._file.read(size))
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@property
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def path(self):
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"""Return path object of tarfile."""
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return self._name
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@property
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def size(self):
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"""Return snapshot size."""
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if not self._name.is_file():
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return 0
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return round(self._name.stat().st_size / 1048576, 2) # calc mbyte
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def _generate_iv(key, salt):
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"""Generate a iv from data."""
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temp_iv = key + salt
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for _ in range(100):
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temp_iv = hashlib.sha256(temp_iv).digest()
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return temp_iv[:16]
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