Creating Encrypted .zip Archives using Mac OSX or Linux

System Requirements: 

Operating System: Mac OSX, Linux (various); creating files for opening in Windows (various)
Installed Packages:

7zip, Keka

MacOS X Instructions: (Use Keka)

In order to create encrypted archive files to send to a Windows user, archiving and encryption should be performed using the file compression and encryption facility Keka.

AES encryption must be enabled before using Keka:

MacOS X built in zip encryption will use the old, weak zip encryption method which should NOT be used.


Linux Instructions: (Use 7zip)

Creation of secure zip archive files on a Linux system should use 7zip (individual Linux distribution installation methods will differ).

1. Copy the files into a new directory which you can access, and have permissions to create new files and directories. Change your current working directory to be that of the new location, or alternatively remember to use full paths in the commands below. The archive will be created in the form of a single file in the same location. 

2. Ensure that you have a password ready to use for the file, which should be sent to the recipient by different means to the archive file (not via email). Please discuss with the RedShield support team if you need assistance with selecting a password transmission method.

3. Run the following commands (items in bold should be substituted for your own values): 

7z a -tzip -mem=AES256 -p"PASSWORD" fileone filetwo filethree

4. Enter password when prompted.

5. You should now find the encrypted archive in the present working directory, or chosen location.  The archive may be opened on Windows systems using a variety of tools including 7-Zip:

6. It may be necessary to rename the file to include a .txt extension when emailing as an attachment, to avoid blocking by mail content filters. 

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