Re: [Tails-dev] Shared screen locking solution for live distributions in Debian

2015-01-13 Thread Micah Lee
On 01/12/2015 03:58 PM, Klaus Knopper wrote:
 Also, screen locking makes only sense if there is the apparent
 possibility that someone else has physical access to the computer while
 the user is not paying attention. Why would I lock the screen if I'm the
 only one using the computer in a safe environment, and shut it down and
 remove the live medium when I'm done with my work.

I outlined some reasons for it here [1], but TL;DR is so you can step
out of your office for a minute to refill your cup of coffee without
having to close all your work, tell everyone you're chatting with that
you'll brb, shut down your computer, and then boot it up again to get
back to work.

[1] https://labs.riseup.net/code/issues/5684#note-11

-- 
Micah Lee
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Re: [Tails-dev] Shared screen locking solution for live distributions in Debian

2015-01-13 Thread Klaus Knopper
Hello Sajolida,

On Wed, Dec 31, 2014 at 02:03:15PM +, sajolida wrote:
 Hi,
 
 I'm part of the people working on Tails, a live distribution that aims
 at preserving privacy and anonymity: https://tails.boum.org/. Tails is
 currently lacking a screen locker and this has been a frequent feature
 request. See https://labs.riseup.net/code/issues/5684.
 
 For example, as Tails is been adopted more and more by journalists,
 they want to be able to leave their computer unattended in their
 office to go to the toilets for a minute and have their screen locked.
 
 I'm writing this emails to various Live distributions based on Debian
 (Knoppix, Grml, Jondo, Kali, Debian Live, and Tanglu). I'm also
 putting Micah Lee in copy as he has shown particular interest in this
 feature.
 
 I've been investigating the screen locking mechanism of those various
 Debian based live distributions, and I found out that none of them had
 a real mechanism to do so. They either:
 
   - Do not provide any screen locking mechanism (Knoppix, Grml,
 Jondo Live).

Actually, Knoppix disables/circumvents the standard Debian screen
locking mechanism because there is no unlocking possible once the
screenlock is active. All passwords are invalid and locked.

   - Either rely on their default password to unlock the screen (Kali,
 Tanglu, Debian Live).
 
 The purpose of this email is to know whether you would be interested
 in working on a common Debian package to provide a generic screen
 locking solution for Debian based live distributions.
 
 The core usability issue that we are facing here is the one of the
 unlocking password. As we are live distributions, there either is no
 password or a default one.

no password in the sense of there is no valid authentication
password, i.e. no backdoor. Sometimes, people mean ANY password if
they say no password, which is not the case for Knoppix. Again, all
passwords are invalid and locked.

 Still, screen locking only make sense if
 the user is able to use a custom password.

Also, screen locking makes only sense if there is the apparent
possibility that someone else has physical access to the computer while
the user is not paying attention. Why would I lock the screen if I'm the
only one using the computer in a safe environment, and shut it down and
remove the live medium when I'm done with my work.

 As an interesting exception,
 note that in Jondo Live, the user is prompted for a user password on
 boot.

Knoppix design is not to ask anything from the boot screen till the
running graphical desktop, with the possible exception of an encrypted
personal overlay.

 In Tails the user can set up an administration password but this
 is disabled by default for security reasons so we cannot rely on this
 for screen locking.
 
 During our last monthly meeting we came up with the idea of asking for
 a custom password *in the process of locking the screen* for the first
 time.

So, when is the right time to lock the screen? Debian does this by
default when the computer goes to standby or the notebook lid is closed.
In this case, the user will hardly pay attention to a dialog asking for
a password.

 For example, in GNOME, when doing Meta+L for the first time, the
 user would be prompted to enter a screen locking password, then only
 the screen would get locked. If she locks the screen again, the same
 password would be reused.

A voluntary screenlock button, asking for a new screenlock (not
necessarily a login) password could be worth a try.

Regards
-Klaus
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Re: [Tails-dev] Shared screen locking solution for live distributions in Debian

2015-01-12 Thread sajolida
sajolida:
 Hi,

Gentle ping regarding what follows as we haven't heard back from your
distribution. Does this seems like an interesting solution for you?
Would you install such a package if it was available in Debian? Would
you put effort in developing or maintaining it?

 I'm part of the people working on Tails, a live distribution that aims
 at preserving privacy and anonymity: https://tails.boum.org/. Tails is
 currently lacking a screen locker and this has been a frequent feature
 request. See https://labs.riseup.net/code/issues/5684.
 
 For example, as Tails is been adopted more and more by journalists,
 they want to be able to leave their computer unattended in their
 office to go to the toilets for a minute and have their screen locked.
 
 I'm writing this emails to various Live distributions based on Debian
 (Knoppix, Grml, Jondo, Kali, Debian Live, and Tanglu). I'm also
 putting Micah Lee in copy as he has shown particular interest in this
 feature.
 
 I've been investigating the screen locking mechanism of those various
 Debian based live distributions, and I found out that none of them had
 a real mechanism to do so. They either:
 
   - Do not provide any screen locking mechanism (Knoppix, Grml,
 Jondo Live).
   - Either rely on their default password to unlock the screen (Kali,
 Tanglu, Debian Live).
 
 The purpose of this email is to know whether you would be interested
 in working on a common Debian package to provide a generic screen
 locking solution for Debian based live distributions.
 
 The core usability issue that we are facing here is the one of the
 unlocking password. As we are live distributions, there either is no
 password or a default one. Still, screen locking only make sense if
 the user is able to use a custom password. As an interesting exception,
 note that in Jondo Live, the user is prompted for a user password on
 boot. In Tails the user can set up an administration password but this
 is disabled by default for security reasons so we cannot rely on this
 for screen locking.
 
 During our last monthly meeting we came up with the idea of asking for
 a custom password *in the process of locking the screen* for the first
 time. For example, in GNOME, when doing Meta+L for the first time, the
 user would be prompted to enter a screen locking password, then only
 the screen would get locked. If she locks the screen again, the same
 password would be reused.
 
 What do you think? Please answer to tails-dev@boum.org and feel free to
 subscribe to the list to follow the thread:
 
 https://mailman.boum.org/listinfo/tails-dev/

-- 
sajolida
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Re: [Tails-dev] Shared screen locking solution for live distributions in Debian

2015-01-01 Thread sajolida
Ed Dixon:
 Hi,

Hi, which project are you from?

 I have been using the xtrlock package which allows the screen to still be
 viewed while locked to good effect in classroom situations. It takes the
 current users password by default. I may be missing something here but as
 far as I am aware all current Debian screen locking mechanisms fill this
 need, if installed. I personally would not want a second set of credentials
 adding a potential vector attached to the user account just to have a
 separate password for the screen lock. Can you explain more the need for
 this?

In the case of live distributions most of the time there is no user
password by default. So if we want to use a password to lock the screen
we need to ask for a password at some point.

I'd like to avoid introducing yet another password if there is one
already (like in the case of Jondo, and sometimes Tails) but otherwise
we need at least one.

Does that make sense?

Note that in the case of Tails, you can configure an administration
password at boot time:
https://tails.boum.org/doc/first_steps/startup_options/administration_password.
I'd like to consider reusing this for screen locking if it is set (and
only ask for a screen locking password if there is none), unless someone
has security concerns about this.

-- 
sajolida
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Re: [Tails-dev] Shared screen locking solution for live distributions in Debian

2015-01-01 Thread Ed Dixon
Hi, I have a project called ediX which is just a minimized Debian for
educational hosting. It is always under heavy redesign but especially so
right now with all of the changes to the Debian Jessie. I recently took
down the web site in order to move it the project to The Foundation for
Learning Equality where I also help with educational projects such as Khan
Academy Light etc.

After reflecting on the question longer the thought finally occurred to me
why others might want or need this second password feature. ediX is
basically default Debian live with a few select packages for a minimum boot
relying on the persistence feature to provide educational software for
services and configuration. The users (teachers) are assumed to not have
shell / linux knowledge and a minimal GUI is made available basically just
for monitoring, changing configurations, and updates. However, tails users
running directly from a live CD without using persistence do not benefit
from having the users credentials saved and thus the need if I am
understanding things correctly. What I would like to see is an easier
method of changing the default password and other user settings in the
Debian live configuration scripts. As a simple precaution I have been
changing user name but allowing live as password for the image however this
all gets changed once the persistence volume is loaded.

As I understand it, Debian Live recommends and defaults to user / live for
the user account credentials and recommends user-setup and sudo packages be
installed in the packages-list providing those features. By adding those
packages that account is created and there are supporting scripts for
changing the default user name and password however I have not had a need
to do so.

Hope this helps!

Thanks,

On Thu Jan 01 2015 at 4:53:33 AM sajolida sajol...@pimienta.org wrote:

 Ed Dixon:
  Hi,

 Hi, which project are you from?

  I have been using the xtrlock package which allows the screen to still be
  viewed while locked to good effect in classroom situations. It takes the
  current users password by default. I may be missing something here but as
  far as I am aware all current Debian screen locking mechanisms fill this
  need, if installed. I personally would not want a second set of
 credentials
  adding a potential vector attached to the user account just to have a
  separate password for the screen lock. Can you explain more the need for
  this?

 In the case of live distributions most of the time there is no user
 password by default. So if we want to use a password to lock the screen
 we need to ask for a password at some point.

 I'd like to avoid introducing yet another password if there is one
 already (like in the case of Jondo, and sometimes Tails) but otherwise
 we need at least one.

 Does that make sense?

 Note that in the case of Tails, you can configure an administration
 password at boot time:
 https://tails.boum.org/doc/first_steps/startup_options/
 administration_password.
 I'd like to consider reusing this for screen locking if it is set (and
 only ask for a screen locking password if there is none), unless someone
 has security concerns about this.

 --
 sajolida

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[Tails-dev] Shared screen locking solution for live distributions in Debian

2014-12-31 Thread sajolida
Hi,

I'm part of the people working on Tails, a live distribution that aims
at preserving privacy and anonymity: https://tails.boum.org/. Tails is
currently lacking a screen locker and this has been a frequent feature
request. See https://labs.riseup.net/code/issues/5684.

For example, as Tails is been adopted more and more by journalists,
they want to be able to leave their computer unattended in their
office to go to the toilets for a minute and have their screen locked.

I'm writing this emails to various Live distributions based on Debian
(Knoppix, Grml, Jondo, Kali, Debian Live, and Tanglu). I'm also
putting Micah Lee in copy as he has shown particular interest in this
feature.

I've been investigating the screen locking mechanism of those various
Debian based live distributions, and I found out that none of them had
a real mechanism to do so. They either:

  - Do not provide any screen locking mechanism (Knoppix, Grml,
Jondo Live).
  - Either rely on their default password to unlock the screen (Kali,
Tanglu, Debian Live).

The purpose of this email is to know whether you would be interested
in working on a common Debian package to provide a generic screen
locking solution for Debian based live distributions.

The core usability issue that we are facing here is the one of the
unlocking password. As we are live distributions, there either is no
password or a default one. Still, screen locking only make sense if
the user is able to use a custom password. As an interesting exception,
note that in Jondo Live, the user is prompted for a user password on
boot. In Tails the user can set up an administration password but this
is disabled by default for security reasons so we cannot rely on this
for screen locking.

During our last monthly meeting we came up with the idea of asking for
a custom password *in the process of locking the screen* for the first
time. For example, in GNOME, when doing Meta+L for the first time, the
user would be prompted to enter a screen locking password, then only
the screen would get locked. If she locks the screen again, the same
password would be reused.

What do you think? Please answer to tails-dev@boum.org and feel free to
subscribe to the list to follow the thread:

https://mailman.boum.org/listinfo/tails-dev/

-- 
sajolida
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Re: [Tails-dev] Shared screen locking solution for live distributions in Debian

2014-12-31 Thread Tobias Frei
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA256

Hi sajolida,

I love this idea and have always been looking for exactly such a
solution. On Tails, I am currently using xlock with a custom
administrator password; here on my Ubuntu PC, xlock does not even
seem to be an existing package.

It would be awesome for me to have a working screen locking tool
shipped with Tails; preferably one that asks me for the used password
before locking the screen. The icing on the cake might be the
possibility to define a password that will be used for locking if the
computer has not been used for an user-defined amount of seconds.

In my opinion, the password should be stored using a strong hashing
algorithm that may well take some seconds to be calculated - the
legitimate user can afford waiting some seconds after entering the
password to unlock the screen; an attacker should have a hard time
extracting the screen lock password even if the built-in software
security mechanisms are somehow circumvented. But I'm not a security
expert and maybe this would just be an illusion of security without
actual benefits.


Best regards,
Tobias Frei



Am 31.12.2014 um 15:03 schrieb sajolida:
 Hi,
 
 I'm part of the people working on Tails, a live distribution that
 aims at preserving privacy and anonymity: https://tails.boum.org/.
 Tails is currently lacking a screen locker and this has been a
 frequent feature request. See
 https://labs.riseup.net/code/issues/5684.
 
 For example, as Tails is been adopted more and more by
 journalists, they want to be able to leave their computer
 unattended in their office to go to the toilets for a minute and
 have their screen locked.
 
 I'm writing this emails to various Live distributions based on
 Debian (Knoppix, Grml, Jondo, Kali, Debian Live, and Tanglu). I'm
 also putting Micah Lee in copy as he has shown particular interest
 in this feature.
 
 I've been investigating the screen locking mechanism of those
 various Debian based live distributions, and I found out that none
 of them had a real mechanism to do so. They either:
 
 - Do not provide any screen locking mechanism (Knoppix, Grml, Jondo
 Live). - Either rely on their default password to unlock the screen
 (Kali, Tanglu, Debian Live).
 
 The purpose of this email is to know whether you would be
 interested in working on a common Debian package to provide a
 generic screen locking solution for Debian based live
 distributions.
 
 The core usability issue that we are facing here is the one of the 
 unlocking password. As we are live distributions, there either is
 no password or a default one. Still, screen locking only make sense
 if the user is able to use a custom password. As an interesting
 exception, note that in Jondo Live, the user is prompted for a user
 password on boot. In Tails the user can set up an administration
 password but this is disabled by default for security reasons so we
 cannot rely on this for screen locking.
 
 During our last monthly meeting we came up with the idea of asking
 for a custom password *in the process of locking the screen* for
 the first time. For example, in GNOME, when doing Meta+L for the
 first time, the user would be prompted to enter a screen locking
 password, then only the screen would get locked. If she locks the
 screen again, the same password would be reused.
 
 What do you think? Please answer to tails-dev@boum.org and feel
 free to subscribe to the list to follow the thread:
 
 https://mailman.boum.org/listinfo/tails-dev/
 
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Re: [Tails-dev] Shared screen locking solution for live distributions in Debian

2014-12-31 Thread Ed Dixon
Hi,
I have been using the xtrlock package which allows the screen to still be
viewed while locked to good effect in classroom situations. It takes the
current users password by default. I may be missing something here but as
far as I am aware all current Debian screen locking mechanisms fill this
need, if installed. I personally would not want a second set of credentials
adding a potential vector attached to the user account just to have a
separate password for the screen lock. Can you explain more the need for
this?
On Wed Dec 31 2014 at 7:27:13 AM sajolida sajol...@pimienta.org wrote:

 Hi,

 I'm part of the people working on Tails, a live distribution that aims
 at preserving privacy and anonymity: https://tails.boum.org/. Tails is
 currently lacking a screen locker and this has been a frequent feature
 request. See https://labs.riseup.net/code/issues/5684.

 For example, as Tails is been adopted more and more by journalists,
 they want to be able to leave their computer unattended in their
 office to go to the toilets for a minute and have their screen locked.

 I'm writing this emails to various Live distributions based on Debian
 (Knoppix, Grml, Jondo, Kali, Debian Live, and Tanglu). I'm also
 putting Micah Lee in copy as he has shown particular interest in this
 feature.

 I've been investigating the screen locking mechanism of those various
 Debian based live distributions, and I found out that none of them had
 a real mechanism to do so. They either:

   - Do not provide any screen locking mechanism (Knoppix, Grml,
 Jondo Live).
   - Either rely on their default password to unlock the screen (Kali,
 Tanglu, Debian Live).

 The purpose of this email is to know whether you would be interested
 in working on a common Debian package to provide a generic screen
 locking solution for Debian based live distributions.

 The core usability issue that we are facing here is the one of the
 unlocking password. As we are live distributions, there either is no
 password or a default one. Still, screen locking only make sense if
 the user is able to use a custom password. As an interesting exception,
 note that in Jondo Live, the user is prompted for a user password on
 boot. In Tails the user can set up an administration password but this
 is disabled by default for security reasons so we cannot rely on this
 for screen locking.

 During our last monthly meeting we came up with the idea of asking for
 a custom password *in the process of locking the screen* for the first
 time. For example, in GNOME, when doing Meta+L for the first time, the
 user would be prompted to enter a screen locking password, then only
 the screen would get locked. If she locks the screen again, the same
 password would be reused.

 What do you think? Please answer to tails-dev@boum.org and feel free to
 subscribe to the list to follow the thread:

 https://mailman.boum.org/listinfo/tails-dev/

 --
 sajolida


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