Verifying signatures

[Rune Philosof]

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?

If so, why not distribute a new one?

[Andrew David Wong]

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."

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

[Ulrich Windl]

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.

[Andrew David Wong]

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.
>>
>