def save_bits_to_file(file_path: str, bits: str, key: bytes, zfec: bool):
"""
save/write bits to a file
file_path -- the path to write to
bits -- the bits to write
key -- key userd for file decryption
zfec -- needed if reed solomon was used to encode bits
"""
bitstring = Bits(bin=bits)
# zip
print("Unziping...")
in_ = io.BytesIO()
in_.write(bitstring.bytes)
in_.seek(0)
# always fails without this but sometimes work with this, unsure why
filetype = magic.from_buffer(in_.read())
print(filetype)
in_.seek(0)
with gzip.GzipFile(fileobj=in_, mode="rb") as fo:
bitstring = fo.read()
# zip
# loading data back from bytes to utf-8 string to deserialize
data = json.loads(bitstring.decode("utf-8"))
# decoding previously encoded base64 bytes data to get bytes back
tag = base64.b64decode(data["tag"])
ciphertext = base64.b64decode(data["data"])
filename = data["filename"]
# decrypting data
cipher = AES.new(key, AES.MODE_EAX, nonce=SALT)
data_bytes = cipher.decrypt(ciphertext)
print("Checking integrity...")
try:
cipher.verify(tag)
except ValueError:
raise WrongPassword("Key incorrect or message corrupted")
bitstring = Bits(data_bytes)
if zfec:
bitstring = Bits("0b" + decode_zfec(data_bytes).decode("utf-8"))
# If filepath not passed in use default otherwise used passed in filepath
if file_path == None:
filepath = filename
else:
filepath = file_path
with open(filepath, "wb") as f:
bitstring.tofile(f)
