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Added integretiy check via sha256.

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Faerbit 2017-05-05 03:06:15 +02:00
parent 7622116ba9
commit e87765418b
1 changed files with 28 additions and 5 deletions
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33
paperize/main.py
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@ -7,6 +7,7 @@ from textwrap import fill
import traceback
from os.path import join, isfile
from tempfile import TemporaryDirectory
from hashlib import sha256
PAPERIZE_VERSION = "v1.0"
@ -27,6 +28,8 @@ PART_TRAILER = "\n---pprz:end---"
FIND_TRAILER = "---pprz:end---"
CHECKSUM = "\n---sha256sum:{sum}---"
TEMPLATE_HEADER = (
"# Paperzied Backup\n"
"_Paperize Version {version}_\n\n"
@ -54,6 +57,15 @@ def mode_file(file_names):
file_contents += file.read()
parts = []
file_contents = file_contents.replace("\n", "")
# extract checksum
begin = file_contents.find("---sha256sum")
# find finds the beginning so we have to add 3
end = file_contents[begin+3:].find("---")
checksum = file_contents[begin:begin+end+6]
file_contents = file_contents.replace(checksum, "")
checksum = checksum.replace("---", "")
checksum = checksum.split(":")[1]
# extract parts
while file_contents:
end = file_contents.find(FIND_TRAILER)
end = end + len(FIND_TRAILER)
@ -90,8 +102,14 @@ def mode_file(file_names):
print(f"File {file_name} exists already. Aborting.", file=stderr)
exit(2)
data = "".join(data)
data = b64decode(data)
with open(file_name, "xb") as file:
file.write(b64decode(data))
file.write(data)
hash = sha256()
hash.update(data)
if (checksum != hash.hexdigest()):
print("Checksum does not match! File might be corrupt!", file=stderr)
exit(2)
def parse_part(part):
"""
@ -103,7 +121,6 @@ def parse_part(part):
# extract header
begin = part.find("---")
part = part[begin:]
# find finds the beginning so we have to add 3
end = part[3:].find("---")
header = part[:end+6]
data = part[end+6:]
@ -134,14 +151,19 @@ def mode_paper(file_name, ec_level):
data = ""
with open(file_name, "rb") as file:
data = file.read()
# calculate sha256 hash
hash = sha256()
hash.update(data)
hash_string = hash.hexdigest()
# convert to base64
data = b64encode(data).decode("utf-8")
# split data
parts = len(data)//MAX_LENGTH[ec_level]
split_data = prepare_data(data, parts, MAX_LENGTH[ec_level], file_name)
split_data = prepare_data(data, parts, MAX_LENGTH[ec_level], file_name,
hash_string)
if (len(split_data) != parts):
split_data = prepare_data(data, len(split_data),
MAX_LENGTH[ec_level], file_name)
MAX_LENGTH[ec_level], file_name, hash_string)
with TemporaryDirectory() as tmpdir:
for i, part in enumerate(split_data, 1):
img = qrcode.make(part,
@ -157,7 +179,7 @@ def mode_paper(file_name, ec_level):
outputfile=f"{file_name}_paperized.pdf",
extra_args=["-V", "geometry:margin=1.5cm"])
def prepare_data(data, no_parts, part_length, file_name):
def prepare_data(data, no_parts, part_length, file_name, hashsum):
"""
Split data into no_parts chunks, while also adding the headers and
trailers.
@ -177,6 +199,7 @@ def prepare_data(data, no_parts, part_length, file_name):
ret.append(part_header + part + PART_TRAILER)
data = fill(data, 80)[length:]
i += 1
ret[-1] = ret[-1] + CHECKSUM.format(sum=hashsum)
return ret