How to compress files as password protected archive using Python

Question

Is there a way to compress gzip or zipfile as a password protected archive? Here is an example code illustrating how to archive file with no password protection:

import gzip, shutil

filepath = r'c:\my.log'

with gzip.GzipFile(filepath + ".gz", "w") as gz:
    with open(filepath) as with_open_file:
        shutil.copyfileobj(with_open_file, gz)

import zipfile

zf = zipfile.ZipFile(filepath + '.zip', 'w')
zf.write(filepath)
zf.close()

So what you are asking for is siomeone else to read the manual for these functions? — stark, Feb 23 '17 at 20:53
[The gzip format does not support password protection](http://superuser.com/a/162625). — kennytm, Feb 23 '17 at 20:53

score 4 · Accepted Answer · edited May 23 '17 at 11:53

4

Python supports extracting password protected zips:

zipfile.ZipFile('myarchive.zip').extractall(pwd='P4$$W0rd')

Sadly, it does not support creating them. You can either call an external tool like 7zip or use a third-party library like this zlib wrapper.

edited May 23 '17 at 11:53

Community

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answered Feb 23 '17 at 20:54

L3viathan

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While `pyminizip` could offer an easy solution for those who create the password protected archives it was very hard to install. Please let me know if you have a recommendation on how to install it on Windows for Python 2.7. – alphanumeric Feb 23 '17 at 23:57
On Windows I would just install 7zip and call it from Python. – L3viathan Feb 24 '17 at 08:11

Mark Adler · Answer 2 · 2018-02-03T21:46:51.980

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Use gpg for encryption. That would be a separate wrapper around the archived and compressed data.

edited Feb 03 '18 at 21:46

answered Feb 23 '17 at 22:16

Mark Adler

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Would you be willing to post an example on how to encrypt the source data (a file or variable), archive it to a `zip` or `gzip` file, then un-archive it and decrypt producing the original uncompressed and decrypted source data. – alphanumeric Feb 24 '17 at 00:06
First off, you got it backwards. You have to archive and compress _before_ encryption, not after. Encrypted data appears random and is not compressible. Second, look at the link for examples. – Mark Adler Feb 24 '17 at 00:25
It is not working for me. I have installed it using `pip install python-gnupg`. Imported module with `import gnupg`. Then I try to initiate the instance with `gpg = gnupg.GPG('C:/temp')` which gives an error message I post below – alphanumeric Feb 24 '17 at 00:41
`Traceback (most recent call last): File "C:\temp\test.py", line 19, in gpg = gnupg.GPG('C:/temp') File "C:\Python27\lib\site-packages\gnupg\gnupg.py", line 125, in __init__ ignore_homedir_permissions=ignore_homedir_permissions, File "C:\Python27\lib\site-packages\gnupg\_meta.py", line 181, in __init__ self.homedir = os.path.expanduser(home) if home else _util._conf` – alphanumeric Feb 24 '17 at 00:42
`File "C:\Python27\lib\site-packages\gnupg\_util.py", line 765, in __set__ getattr(obj, self.fset.__name__)(value) File "C:\Python27\lib\site-packages\gnupg\_meta.py", line 438, in _homedir_setter raise RuntimeError(str(ae)) RuntimeError: Homedir ''C:\temp\gnupghome\.config\python-gnupg'' needs read/write permissions` – alphanumeric Feb 24 '17 at 00:43
@MarkAdler if you encrypt a compressed file, doesn't that lead to a vulnerability? The compressed file adheres to strict protocols on header, footer, etc. So a cracker would have some plain text from within your encrypted file to work with in the search for the password. – hobs Feb 16 '20 at 22:59
@hobs gpg precedes the compressed data with a small amount of random data before encryption for this reason. – Mark Adler Feb 17 '20 at 01:12
@MarkAdler yes, but that just obsficates the location of the header in the encrypted text, it does not change the presence of the plaintext header itself. So a brute force attack would merely have to grep for the header within the trial and error decompressed files. Salting, I think, is an attempt to mitigate this vulnerability, but that does not change the fact that it is a vulnerability: https://stackoverflow.com/a/29836684/623735 – hobs Feb 17 '20 at 19:21

How to compress files as password protected archive using Python

2 Answers2