Using an OpenPGP Smart Card on Mac OS X
I use an OpenPGP smart card with a Gemalto IDBridge K50 USB card reader.
This post details how I configure my Mac OS X install for SSH authentication using the smart card.
This post doesn't explain how to create your GPG key or how to move it to the card.
If you need to know how to create your keys, I used http://www.bootc.net/archives/2013/06/07/generating-a-new-gnupg-key/ as a guide to create mine (this assumes you're running Debian).
This post assumes you have:
- a Mac running OS X 10.10 Yosemite
- a Gemalto IDBridge K50 USB smart card reader containing a OpenPGP smart card
- your GPG keys already loaded on to your smart card
Setting it up
- First off, install GPG Suite from gpgtools.org.
- Once you've installed the GPG Suite, open a Terminal.
- We need to disable the standard SSH agent, so run:
sudo launchctl unload -w /System/Library/LaunchAgents/org.openbsd.ssh-agent.plist
- I found that my GPG agent would randomly die unless I disable the
org.gpgtools.macgpg2.shutdown-gpg-agent.plistLaunchAgent. To disable this, run:
sudo launchctl unload -w /Library/LaunchAgents/org.gpgtools.macgpg2.shutdown-gpg-agent.plist
- We'll need to edit your
gpg-agent.conf. Open it in your favourite editor and make sure it contains:
enable-ssh-support pinentry-program /usr/local/MacGPG2/libexec/pinentry-mac.app/Contents/MacOS/pinentry-mac write-env-file use-standard-socket
- To have apps on the console work correctly that expect to use the GPG or SSH agent, you'll need to add some lines to the
.profilefile in your home directory. Open
~/.profilein your favourite editor and make sure it contains the following:
export SSH_AUTH_SOCK=~/.gnupg/S.gpg-agent.ssh GPG_TTY=`tty` export GPG_TTYTo apply this to your current console, run
- For OSX GUI applications to see the GPG agent properly, you'll need to create your own LaunchAgent plist file that sets the environment variable. After doing this, you can (for example) use the GPG key to authenticate in SourceTree.
The normal naming scheme for plists is to use your domain name backwards, then a description of the purpose of the file. In this example, my file is called
~/Library/LaunchAgents/uk.tomjepp.sshenv.plistin your favourite editor and insert the following:
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>setenv.SSH_AUTH_SOCK</string> <key>ProgramArguments</key> <array> <string>/bin/launchctl</string> <string>setenv</string> <string>SSH_AUTH_SOCK</string> <string>/Users/thomas/.gnupg/S.gpg-agent.ssh</string> </array> <key>RunAtLoad</key> <true/> <key>ServiceIPC</key> <false/> </dict> </plist>Replace
/Users/thomas/.gnupg/S.gpg-agent.sshwith your own username.
- To enable that new plist, run:
launchctl load -w ~/Library/LaunchAgents/uk.tomjepp.sshenv.plist
At this point, you should be able to freely unplug and plug back in your GPG card - and it should keep working whenever you do!
This setup works nicely for me on two Macs - for SSH auth using the command line SSH client as well as pushing and pulling source code over Git/SSH using SourceTree.
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