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I need to make an encrypted file on a PC that I can burn to CD and give a mac user who wants to decrypt it without having to install a program? is this even possible? thanks

An Dorfer
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Gavril
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3 Answers3

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The only way I know of is by putting the file inside a ZIP archive with password.
These can be unpacked with the standard unzip on the Mac.
Anything else requires addon software on the Mac.

Tonny
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Edit: truecrypt is discontinued as of 28 May 2014
You could look at VeraCrypt for similar functionality.

Safest way would be truecrypt.
It has a portable mode so you won't have to install software.

Here are the instructions to make Truecrypt portable for the Mac. (by dragging the ".app" to your cd/usb).

Otherwise you'll need to use software which is standard on both computers.

Is "zipping" it with a password not an option?

If you are going to use a zip with password make sure to use the strongest encryption available to both systems. The older encryption methods are relatively weak.

Rik
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  • Does the portable mode work on OSX, too? – ChrisInEdmonton Oct 08 '13 at 21:33
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    Yep. Just added the info/link to my answer. You'll need to extract the .app for the mac and send it with the .tc container with your data. – Rik Oct 08 '13 at 21:35
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    @ChrisInEdmonton Yes. You can even put the TrueCrypt portable OSX and Windows binaries both on the same CD together with the TrueCrypt volume. ZIP with password is probably easier to explain to the receiver though,,,, – Tonny Oct 08 '13 at 21:36
  • Don't use truecrypt, they dropped development ages ago and it has unresloved security issues. – Cestarian Jan 04 '20 at 23:03
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    @Cestarian I edited the post and added VeraCrypt as alternative. – Rik Jan 06 '20 at 09:37
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The only cross platform encrypted documents supported out-of-the-box in macOS and Windows are encrypted ZIP files. However, only the very weak ZipCrypto encryption is supported, which is easily crackable. AES encrypted ZIP files are not supported and require additional software like 7Zip.

The other option is to consider is PDF that Chrome, Edge and Safari support. However, you will need to pay attention to careful selection of encryption algorithms in PDF (RC4, AES128, AES256v1, AES256v2) as some of them are vulnerable to bruteforce like RC4 and AES256v1. Also, keep in mind missing integrity checks in PDF files, which might allow bypassing encryption in some cases if a a man-in-the-middle is able to substitute the document before the end-user opens it.

There are other options using executable code but they are highly likely will be blocked by anti-spam/antivirus systems.

coder56
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