Clarify language and procedure

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Axon 2015-09-21 13:15:22 +00:00
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@ -11,12 +11,10 @@ Using Multi-factor Authentication with Qubes
severices, not for logging into Qubes itself. For the latter, see
[here][YubiKey].)
[Multi-factor authentication (MFA)][MFA] is a method of computer access control
which a user can pass by successfully presenting several separate authentication
stages. Nowadays, this most commonly takes the form of a numerical code
generated by a smartphone app or sent via SMS (text message) which the user must
enter in addition to a password in order to log in to a website or other
service.
[Multi-factor authentication (MFA)][MFA] today most commonly takes the form of a
numerical code generated by a smartphone app or sent via SMS (text message)
which the user must enter in addition to a password in order to log in to a
website or other service.
One of the primary features of Qubes is that it allows us to create securely
isolated VMs which can run arbitrary programs. (These VMs are securely isolated
@ -24,13 +22,14 @@ not only from each other but also, optionally, from the network.) This means
that we can create a dedicated, network-isolated VM to function as a secure
authenticator.
This guide will show you how to set up a VM which uses [oathtool][], an open-
source one-time password tool, to generate authentication codes. This method
presents several benefits over relying on a consumer smartphone app or SMS:
This guide will show you how to set up a VM which uses [oathtool][], an
open-source one-time password tool, to generate authentication codes. This
method presents several benefits over relying on a consumer smartphone app or
SMS:
* `oathtool` includes the [time-based one-time password (TOTP)][TOTP]
algorithm, which is the same algorithm used by Google Authenticator, one of
the most commonly used authenticator apps. This means that we can use
algorithm, which is the same algorithm used by [Google Authenticator][], one
of the most commonly used authenticator apps. This means that we can use
`oathtool` as a complete open-source replacement for Google Authenticator
(which became propriety (closed-source) in May 2013 after version 2.21).
@ -47,9 +46,9 @@ presents several benefits over relying on a consumer smartphone app or SMS:
over the device. Likewise, consumer SMS messages are often cleartext
communications which can feasibly be intercepted and read by third parties.
(In cases in which SMS messages are encrypted on the network by the service
provider, the service provider itself of course still has full access, which
means that the contents of such messages could be read by unscrupulous admins
or turned over to government agencies.)
provider, the service provider itself still has full access, which means that
the contents of such messages could be read by unscrupulous admins or turned
over to government agencies.)
* Using `oathtool` in a dedicated, network-isolated Qubes VM allows us to
achieve a unqiue combination of security and convenience. The strong isolation
@ -73,34 +72,40 @@ Optional Preparation Steps
[user@dom0 ~]$ qvm-clone fedora-21-minimal fedora-21-min-mfa
3. Since this is going to be a minimal environment in which we run `oathtool`
from the command line, we need to install only a couple of packages:
from the command line, we'll install only a couple of packages:
[user@fedora-21-min-mfa ~]$ su -
[user@fedora-21-min-mfa ~]# yum install oathtool vim-minimal
[user@fedora-21-min-mfa ~]$ poweroff
4. Create an AppVM and set it to use `fedora-21-min-mfa` as its TemplateVM.
4. Create an AppVM and set it to use the TemplateVM we just created:
[user@dom0 ~]$ qvm-create -l black mfa
[user@dom0 ~]$ qvm-prefs -s mfa template fedora-21-min-mfa
5. Ensure that the new AppVM's netvm is set to `none`.
5. Isolate the new AppVM from the network:
[user@dom0 ~]$ qvm-prefs -s mfa netvm none
Using `oathtool` in an AppVM
----------------------------
Using the MFA AppVM
-------------------
Now that we have an AppVM set up to use `oathtool` securely, let's use it with
an external service. This process will vary slightly from service to service but
is largely the same.
1. Proceed with setting up multi-factor authentication as you normally would.
If you are prompted to scan a QR code with your smartphone, instead select
the option (if available) to view the secret key as text:
If you are prompted to scan a QR code, instead select the option (if
available) to view the secret key as text:
![Secret Key Example 0](/attachment/wiki/UserDoc/Multi-factorAuthentication/secret-key-example-0.png)
You should then see something like this:
You should then see the secret key as text:
![Secret Key Example 1](/attachment/wiki/UserDoc/Multi-factorAuthentication/secret-key-example-1.png)
Note that the length of the secret key may vary:
Note that the length and format of the secret key may vary by service:
![Secret Key Example 2](/attachment/wiki/UserDoc/Multi-factorAuthentication/secret-key-example-2.png)
@ -120,9 +125,9 @@ is largely the same.
after a short period of time.)
3. To make this easier on ourselves in the future, we can create a simple shell
script for each service we use. (The example here is Google, using the
example key from above. You'll get a different secret key from each service
which is unique to you.) Create the script like so:
script for each service we use. (The example service here is a Google
account, using the example key from above. You'll get a unique secret key
from each service.) Create the script like so:
[user@mfa ~]$ > google
[user@mfa ~]$ vi google
@ -145,9 +150,9 @@ is largely the same.
Done!
5. Create similar scripts for other services you use, and enjoy the security
and ease of quickly generating TOTP tokens right from your Qubes VM
command-line:
5. Now you can create scripts for any other TOTP-supporting services you use,
and enjoy the security and ease of quickly generating authentication tokens
right from your Qubes VM command-line:
[user@mfa ~]$ ./github
495272
@ -173,5 +178,6 @@ is largely the same.
[MFA]: https://en.wikipedia.org/wiki/Multi-factor_authentication
[oathtool]: http://www.nongnu.org/oath-toolkit/man-oathtool.html
[TOTP]: https://en.wikipedia.org/wiki/Time-based_One-time_Password_Algorithm
[Google Authenticator]: https://en.wikipedia.org/wiki/Google_Authenticator
[FedoraMinimal]: /doc/Templates/FedoraMinimal/
[usage]: https://en.wikipedia.org/wiki/Google_Authenticator#Usage