How to Decrypt Files Using GPG
This help file is intended to give more detailed, platform-specific
instructions on how to decrypt files using GNU Privacy Guard (GPG) for those
that need it.
First, some background: File encryption is required by U.S. Federal law
when transmitting the proprietary information utilized in peer reviews. We
have endeavored to make this process as simple as possible while using free
software that is supported on all popular OS platforms, but we recognize that
it is obviously not as easy as it could be. Please accept our apologies for
the inconvenience and our thanks for the additional time and effort it takes
to decrypt these files.
First, download and install the latest version of
You will need administrator access to install it. Make sure you install
the GPA component. It may not be part of the default installation.
After GPG4Win has been successfully installed, launch GPA (gpa.exe),
either by clicking on its icon or selecting it from the Windows "Start"
After it has launched, click on the "Files" icon in the toolbar of the
"GNU Privacy Assistant - Key Manager" window. It is the third icon from the
right in the toolbar, next to the "Clipboard" icon. This will open up the
"GNU Privacy Assistant - File Manager" window.
In that window, click on the "Open" icon in the toolbar (the first
icon on the left of the "File Manager" toolbar) and then navigate to the
encrypted (*.asc) file and open it. The file should now be listed in the
"File Manager" window.
Finally, click on the "Decrypt" button. This will present a dialog box
for you to enter the passphrase. Type (or paste) the passphrase, which
should have already been supplied to you by the mission's peer review
staff. After a few moments, the file will be decrypted and you can quit
You will likely still need to untar the decrypted file, but there are
many Windows programs to do that (e.g.,
7zip, WinZip, Winrar,
Winace), and you may already have one of those utilities
Alternatively, you can use the command line interface in a
Terminal session. Note that the executable may be named "gpg2.exe"
instead of "gpg.exe". It will probably be installed in
C:\Program Files\GNU\GnuPG\. If that is the case, you should amend the
recommended command line from "gpg" to "gpg2" accordingly.
First, download the
Guard for Mac OS X installer. We recommend downloading the latest 1.4.x
version, which is 1.4.11-6 at the time of this writing. Alternatively,
you could download and install the
to use GPG 2.0.x instead. If you do that, we recommend that you customize
the installation and only install the "MacGPG2" sub-package (unless you
plan on using GPG for other things on your Mac).
Locate the downloaded image file ("MacGPG1-1.4.11-6.dmg" or
"GPG_Suite-2016.10_v2.dmg" or similar) in the Finder and double-click it
to mount it.
After the image mounts, double-click on the "MacGPG1.pkg"
installer package (or, alternatively, the "Install" icon if you
downloaded the GPG Suite) and follow the installer's instructions
to install GPG on your Mac. You will need administrator access to do
Next, launch the Terminal application, which should be located in the
"Utilities" folder inside your main "Applications" folder. (Use Spotlight
to locate it by searching for "Terminal", if necessary.)
Once you have a Terminal window open, you will need to change directory
to where the encrypted file was downloaded. For example, if the encrypted
file is in your Downloads folder, you would type:
If the encrypted file is on your desktop, you would type:
If the encrypted file is in your home directory, you would just type:
Finally, copy and paste one of the Unix-compatible commands for
decrypting files, as given in the peer review instructions, into the
Terminal window. The second command should work on Mac OS X and is
recommended. If you get an error in the Terminal window that says "gpg:
command not found" or similar, replace "gpg" with
"/usr/local/MacGPG1/bin/gpg" in the decryption command and try again.
If that doesn't work, try "/usr/local/bin/gpg" instead.
If you installed the GPG Suite, you should use
Commands to use to determine where GPG was installed:
You may find it convenient to create a command alias so that you
do not have to type the complete path each time. Depending on what type
of shell you are using, you can do that by typing one
of the following commands in a Terminal window (for the bash
If your shell is tcsh instead, defining an alias is the same
except you should not type the equal sign (=) in the above examples.
If you are not sure what shell you are using or this is confusing, you
can just skip defining an alias and instead just type the full path to
the command when issuing the decryption command.
Depending on which Terminal command you used, you might still need to
untar the decrypted file. We recommend utilizing the free utility
Unarchiver for that purpose. It can also be downloaded for free from
the Mac App Store.
Most popular Linux distros ship with GPG already installed. You should be
able to just copy and paste the decryption command (as given in the peer
review instructions) into any terminal window. If not, consult your distro's
software package manager on
install GPG (a.k.a. "gnupg"). Alternatively, the
source code is