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level1archer

Member

Registered: 2022-07-02

Posts: 3

[SOLVED] Sharing an encrypted file with someone on Windows?

Hi I'm new! I'm not an encryption expert, but on OSX I was able to print a document as a PDF and it had a "Security Options" type section where I could encrypt the PDF. What's the best way to do this on Arch Linux? Thanks!

Last edited by level1archer (2022-07-03 04:16:49)

progandy

Member

Registered: 2012-05-17

Posts: 5,319

Re: [SOLVED] Sharing an encrypted file with someone on Windows?

If it is a pdf file, you could use pdf encryption with e.g. podofoencrypt from podofo (set owner and user password and use --aesv3)
7zip (or PeaZip) is available on windows, so a 7z archive with a password (AES-256) works.

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level1archer

Member

Registered: 2022-07-02

Posts: 3

Re: [SOLVED] Sharing an encrypted file with someone on Windows?

If it is a pdf file, you could use pdf encryption with e.g. podofoencrypt from podofo (set owner and user password and use --aesv3)
7zip (or PeaZip) is available on windows, so a 7z archive with a password (AES-256) works.

Hey! Just wanted to thank you so much for the helpful reply. I had a really long day and appreciate it. I had one followup question for you (or anyone else reading). I did as you instructed with podofoencrypt and it worked out great. When reading the man page I noticed it says  under the `--aes` option: "currently not supported". Also, I didn't see an `--aesv3` option in the man page. Is that something that you could elaborate on more? I'm a super noob when it comes to encryption stuff.

Thanks again!

lfitzgerald

Member

Registered: 2021-07-16

Posts: 175

Re: [SOLVED] Sharing an encrypted file with someone on Windows?

GPG is the standard encryption tool for any type of file, and there are many GPG suites for all OSes, including Windows, OS X and of course Arch Linux. Here's one I found for Windows: https://www.gpg4win.org/

I find that a lot of windows users are familiar with encrypted zip files, which is something you could use if you're trying to minimize the skill barrier. 7zip also supports this (as pointed out by progandy). So does RAR (eg. WinRAR).

You could also use VeraCrypt, but then the recipient would probably need to have VeraCrypt installed as well.

Last edited by lfitzgerald (2022-07-03 01:40:43)

mpan

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Registered: 2012-08-01

Posts: 1,612

Website

Re: [SOLVED] Sharing an encrypted file with someone on Windows?

I second the 7-zip option. Not only for Windows or less tech savvy users. I see it as the method of sharing files privately with everybody, unless some other solution has been negotiated beforehead. It simply works frictionlessly.

And I support that even for a single PDF. That’s because it leaves choice, of how to use the file, to the recipient. To get rid of PDF’s encryption, one needs a reader that support such an option.⁽¹⁾ Even worse if their reader supports restriction hints and you messed those up, making it PITA to use the file.

There is a minor contention point, regarding 7-zip security: Pavlov’s diminishing of importance of the IV randomness bug. But for just normal day-to-day use I would not be worried too much about that single event, considering that the encryption used is well-tested and benefits 7-zip itself gives.
____
⁽¹⁾ Other than creating a new PDF through “printing to PDF”.

Last edited by mpan (2022-07-03 02:40:48)

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progandy

Member

Registered: 2012-05-17

Posts: 5,319

Re: [SOLVED] Sharing an encrypted file with someone on Windows?

I did as you instructed with podofoencrypt and it worked out great. When reading the man page I noticed it says  under the `--aes` option: "currently not supported". Also, I didn't see an `--aesv3` option in the man page. Is that something that you could elaborate on more? I'm a super noob when it comes to encryption stuff.

The manpage is out of date:

% podofoencrypt --help
Usage: podofoencrypt [--rc4v1] [--rc4v2] [--aesv2] [--aesv3] [-u <userpassword>]
                     -o <ownerpassword> <inputfile> <outputfile>

       This tool encrypts an existing PDF file.

       --help        Display this help text
 Algorithm:
       --rc4v1       Use rc4v1 encryption
       --rc4v2       Use rc4v2 encryption (Default value)
       --aesv2       Use aes-128 encryption
       --aesv3       Use aes-256 encryption
 Passwords:
       -u <password> An optional userpassword
       -o <password> The required owner password
 Permissions:
       --print       Allow printing the document
       --edit        Allow modifying the document besides annotations, form fields or changing pages
       --copy        Allow text and graphic extraction
       --editnotes   Add or modify text annoations or form fields (if ePdfPermissions_Edit is set also allow the creation interactive form fields including signature)
       --fillandsign Fill in existing form or signature fields
       --accessible  Extract text and graphics to support user with disabillities
       --assemble    Assemble the document: insert, create, rotate delete pages or add bookmarks
       --highprint   Print a high resolution version of the document

I find that a lot of windows users are familiar with encrypted zip files, which is something you could use if you're trying to minimize the skill barrier.

You should really avoid ZIP encryption. Windows only supports the insecure method, so if you use the secure method you'll have to explain the windows user that the zip is not broken, but that they need another tool and not the windows explorer to open it.

There is a minor contention point, regarding 7-zip security: Pavlov’s diminishing of importance of the IV randomness bug. But for just normal day-to-day use I would not be worried too much about that single event, considering that the encryption used is well-tested and benefits 7-zip itself gives.

Another option might be the .PEA archive format of PeaZip, but that is not as well known and probably not well tested.

Last edited by progandy (2022-07-03 07:18:31)

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level1archer

Member

Registered: 2022-07-02

Posts: 3

Re: [SOLVED] Sharing an encrypted file with someone on Windows?

The manpage is out of date:

Thanks so much for the follow up, and again for your help.