Re: [EXT] Re: [qubes-users] Verifying signatures

2021-11-30 Thread Andrew David Wong

On 11/30/21 10:18 AM, Ulrich Windl wrote:

On 11/30/21 12:32 PM, Andrew David Wong wrote:

On 11/29/21 12:06 PM, 'Rune Philosof' via qubes-users wrote:

When I follow the guide
on https://www.qubes-os.org/security/verifying-signatures/
I get the following result
```
[vagrant@fedora ~]$ gpg2 --check-signatures "Qubes Master Signing Key"
pub   rsa4096 2010-04-01 [SC]
   427F11FD0FAA4B080123F01CDDFA1A3E36879494
uid   [ultimate] Qubes Master Signing Key
sig!3    DDFA1A3E36879494 2010-04-01  Qubes Master Signing Key

gpg: 1 good signature
[vagrant@fedora ~]$ gpg2 --check-signatures "Qubes OS Release 4 
Signing Key"

pub   rsa4096 2017-03-06 [SC]
   5817A43B283DE5A9181A522E1848792F9E2795E9
uid   [ unknown] Qubes OS Release 4 Signing Key
sig!3    1848792F9E2795E9 2017-03-06  Qubes OS Release 4 Signing Key
gpg: Note: third-party key signatures using the SHA1 algorithm are 
rejected

gpg: (use option "--allow-weak-key-signatures" to override)
sig% DDFA1A3E36879494 2017-03-08  [Invalid digest algorithm]

gpg: 1 good signature
gpg: 1 signature not checked due to an error
```

Is it because the master key is old and the old defaults are now
considering too weak?


I take it you're referring to the message about SHA1. I'm not certain, 
but we do have a related open issue, which the devs are working on now:


https://github.com/QubesOS/qubes-issues/issues/6470

Also see the comments on this issue, which are even more specific to 
your question:


https://github.com/QubesOS/qubes-issues/issues/4378

In particular, Marek commented (on #4378):

"In general, it may be a good idea to create new signature using 
SHA256 or such, to ease the use with weak-digest SHA1 option enabled. 
But in practice, in the current state SHA1 problems doesn't affect 
security of the key itself, because there are no known pre-image attacks.

New signatures are made with SHA256 hash function."


If so, why not distribute a new one?



It's not that simple. As Marek recently pointed out to me, "The 
current QMSK is well known and published in a lot of places (easing 
its verification), including various conference videos, physical 
t-shirts we sold, some stickers etc. With every new QMSK it will take 
time until it will be comparably easy to independently verify."


But isn't that exactly the advantage of the "web of trust"?: You can 
sign the new key with your old key, and people will (have the chance to) 
trust the new key as well.




The Web of Trust is only one of several different methods for 
authenticating the QMSK. Many of our users do not use the Web of Trust. 
Please read this for further details:


https://www.qubes-os.org/security/verifying-signatures/#how-to-import-and-authenticate-the-qubes-master-signing-key



Having said that, we do have an open issue for generating a new QMSK:

https://github.com/QubesOS/qubes-issues/issues/2818

We likely will at some point, but it's not an action to be taken lightly.





--
Andrew David Wong
Community Manager
The Qubes OS Project
https://www.qubes-os.org

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Re: [EXT] Re: [qubes-users] Verifying signatures

2021-11-30 Thread Ulrich Windl

On 11/30/21 12:32 PM, Andrew David Wong wrote:

On 11/29/21 12:06 PM, 'Rune Philosof' via qubes-users wrote:

When I follow the guide
on https://www.qubes-os.org/security/verifying-signatures/
I get the following result
```
[vagrant@fedora ~]$ gpg2 --check-signatures "Qubes Master Signing Key"
pub   rsa4096 2010-04-01 [SC]
   427F11FD0FAA4B080123F01CDDFA1A3E36879494
uid   [ultimate] Qubes Master Signing Key
sig!3    DDFA1A3E36879494 2010-04-01  Qubes Master Signing Key

gpg: 1 good signature
[vagrant@fedora ~]$ gpg2 --check-signatures "Qubes OS Release 4 
Signing Key"

pub   rsa4096 2017-03-06 [SC]
   5817A43B283DE5A9181A522E1848792F9E2795E9
uid   [ unknown] Qubes OS Release 4 Signing Key
sig!3    1848792F9E2795E9 2017-03-06  Qubes OS Release 4 Signing Key
gpg: Note: third-party key signatures using the SHA1 algorithm are 
rejected

gpg: (use option "--allow-weak-key-signatures" to override)
sig% DDFA1A3E36879494 2017-03-08  [Invalid digest algorithm]

gpg: 1 good signature
gpg: 1 signature not checked due to an error
```

Is it because the master key is old and the old defaults are now
considering too weak?


I take it you're referring to the message about SHA1. I'm not certain, 
but we do have a related open issue, which the devs are working on now:


https://github.com/QubesOS/qubes-issues/issues/6470

Also see the comments on this issue, which are even more specific to 
your question:


https://github.com/QubesOS/qubes-issues/issues/4378

In particular, Marek commented (on #4378):

"In general, it may be a good idea to create new signature using SHA256 
or such, to ease the use with weak-digest SHA1 option enabled. But in 
practice, in the current state SHA1 problems doesn't affect security of 
the key itself, because there are no known pre-image attacks.

New signatures are made with SHA256 hash function."


If so, why not distribute a new one?



It's not that simple. As Marek recently pointed out to me, "The current 
QMSK is well known and published in a lot of places (easing its 
verification), including various conference videos, physical t-shirts we 
sold, some stickers etc. With every new QMSK it will take time until it 
will be comparably easy to independently verify."


But isn't that exactly the advantage of the "web of trust"?: You can 
sign the new key with your old key, and people will (have the chance to) 
trust the new key as well.




Having said that, we do have an open issue for generating a new QMSK:

https://github.com/QubesOS/qubes-issues/issues/2818

We likely will at some point, but it's not an action to be taken lightly.



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