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What is a good way to encrypt a PDF to send by email?

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neutrino17

macrumors regular
Original poster
Jun 25, 2022
114
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I just spoke with Apple support and there is not an encryption function for file level encryption in the Finder.

Preview can password PDFs (and apparently encrypt them) but there is no information about how the level of encryption.

I rarely need this, but now I need to email a couple of PDF files with some sensitive information. What is normally done in this case?

I'm emailing a PDF to a lawyer and I assume they are using Windows so I need a cross platform solution. Otherwise I could make an encrypted volume.

Thanks.
 
I use WinZip for Mac - I currently have Version 8 (Version 9 is the latest). It allows you to set the Encryption method to:

  • WinZip 2.0
  • AES 128-bit
  • AES 256-bit
As it is across platform application, its files can be opened on Windows.

I often use it for sending sensitive information and I have not encountered any issues.

1683586440921.png
 
neutrino17 said:
Preview can password PDFs (and apparently encrypt them) but there is no information about how the level of encryption.
Click to expand...

The level of encryption depends on the PDF version. You can see the version level of the PDF document in Get Info.

Early versions of MacOS saved with PDF v1.4, giving RCA-128bit encryptions. Newer versions save as PDF v1.6, giving AES-128 encryption. The encrypted PDFs made by Preview are valid PDFs that can be opened (when the password is provided) by any PDF app that follows the spec on any platform.
 
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are the .zip files encrypted or password protected? as i believe password protection can be broken
 
MacBH928 said:
are the .zip files encrypted or password protected? as i believe password protection can be broken
Click to expand...
Zip 2.0=ZipCrypto
"You should not rely on Zip 2.0 encryption to provide strong security for your data."
https://kb.winzip.com/help/help_encryption.htm
"ZipCrypto, for legacy compatibility purpose only as the algorithm is considered weak under today's standards, not recommended to protect sensitive data"
https://peazip.github.io/encrypt-files.html
Keka - Password protected and encrypted files
https://github.com/aonez/Keka/wiki/Compressing-with-Keka#password-protected-and-encrypted-files
 
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tonmischa said:

Keka - the macOS file archiver

www.keka.io www.keka.io

Creates and decompresses 7z, zip, tar and a bunch of other formats.
You can also encrypt 7z and zip files. For zip there is even an AES256 Option.
Click to expand...
I just purchased it and tried it. It works reasonably well. My question is, whether a Windows 10/11 user receiving an encrypted 7z archive from me will be able to decrypt it without requiring him to install any utility software not part of the out-of-the-box Windows distribution.

Also, I found that Apple’s own Archive Utility
Archive Utility.png

which launches, when double-clicking a .7z file will ask for the decryption password but then pops up the password dialog again:
Screenshot 2023-08-31 at 11.30.59 AM.png

It evidently cannot handle the particular encryption format that Keka used. Keka itself can decrypt the file successfully.
 
You can do this with a free proton mail account. That has the advantage that the email itself is encrypted.
 
FYI, my solution was that the office I was communicating with setup a link to a secure portal for uploading files. I didn’t have to use email.
 
DominikHoffmann said:
I just purchased it and tried it. It works reasonably well. My question is, whether a Windows 10/11 user receiving an encrypted 7z archive from me will be able to decrypt it without requiring him to install any utility software not part of the out-of-the-box Windows distribution.

Also, I found that Apple’s own Archive Utility
View attachment 2253270
which launches, when double-clicking a .7z file will ask for the decryption password but then pops up the password dialog again:
View attachment 2253271
It evidently cannot handle the particular encryption format that Keka used. Keka itself can decrypt the file successfully.
Click to expand...
7z is a 3rd-Party-Format, which requires 3rd-Party Software.
Win and Mac do not support 7z out-of-the box.
Mac also does not support encrypted Zips out-of-the-box.
That’s why I recommended Keka.

BTW: Keka is free software.
 
tonmischa said:
Mac also does not support encrypted Zips out-of-the-box.
Click to expand...
macOS can generated encrypted ZIP files from the command line. Those can be opened by double-clicking in the Finder, which will put up a dialog asking for the encryption password.
tonmischa said:
BTW: Keka is free software.
Click to expand...
Absolutely correct! I opted to purchase the software for the convenience of receiving updates through the App Store.
 
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