Re: verifying archive signature keys?
Martin Zobel-Helas <zobel@ftbfs.de> writes:
> Hi,
>
> On Wed Aug 15, 2007 at 10:54:02 +0200, Hadmut Danisch wrote:
>> Hi,
>>
>> just a question because someone had asked me for help. The problem was
>> that apt-get update had complained about not beeing able to verify
>> signatures due to a missing pgp key.
>>
>> Was easy to tell to do
>> gpg --recv-key A70DAF536070D3A1
>> gpg -a --export A70DAF536070D3A1 | sudo apt-key add -
>>
>>
>>
>> but: How would one verify that this key is the correct debian
>> key (and not, e.g. the key used by an intruder to fake packages and
>> simply uploaded to public key repositories)?
>>
>>
>> gpg --check-sigs A70DAF536070D3A1
>>
>> lists some signatures of several people, but none that I personally
>> know, I don't even know whether these people actually exist.
>
> The best way to check this, is to check against the Debian Keyring.
> Either you download the Debian Keyring from keyring.debian.org like:
> rsync -az --progress \
> keyring.debian.org::keyrings/keyrings/debian-keyring.gpg \
> ./debian-keyring.gpg
> and check against this keyring, or you check the Key-IDs via
> http://db.debian.org/, but you need the fingerprint of those key IDs
> then.
>
> Greetings
> Martin
Which doesn't really solve anything as you can't trust those sources
anymore than the initial key.
You have to look for a trust path between you and the debian key. As
you said the debian key has signatures by a number of people, none of
which you know. Those people have signatures on their keys from other
people and those again from even more people. After a few such steps
you hopefully end up with a person you know or met once and then you
have a trust path.
There should be a lot of trust paths, the more the better and the
shorter the path the better.
MfG
Goswin
PS: Another way is to trust your Debian CD you bought some time ago
and use the keyring on that CD.
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