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How to check the trust level

 

 

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ratzip at 163

Nov 21, 2009, 10:48 AM

Post #1 of 5 (824 views)
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How to check the trust level

HI,guys
If some one has signed my key and set the trust level on my key, how could I check the trust level he set?
which commands should I use?



--
点击,与我一起为中国加油,爽!


dshaw at jabberwocky

Nov 21, 2009, 2:22 PM

Post #2 of 5 (776 views)
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Re: How to check the trust level [In reply to]

On Nov 21, 2009, at 1:48 PM, ratzip wrote:

> HI,guys
> If some one has signed my key and set the trust level on my key, how
> could I check the trust level he set?
> which commands should I use?

It depends on what you mean by "trust level". If you mean the
ownertrust, then you can't - that's personal to him and is not visible
outside of his machine. If you mean the signature verification level,
then it is visible in the --list-sigs output - 3 for "positive"
verification, 2 for "casual" verification, and 1 for "persona" (aka
didn't check) verification. If none of these numbers appear, it's a
"generic" verification.

David


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dkg at fifthhorseman

Nov 21, 2009, 2:47 PM

Post #3 of 5 (774 views)
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Re: How to check the trust level [In reply to]

On 11/21/2009 01:48 PM, ratzip wrote:
> If some one has signed my key and set the trust level
> on my key, how could I check the trust level he set?
> which commands should I use?

For the typical way that GPG manages ownertrust, that information is not
published (or publishable) at all.

In the unlikely event that your contact has made a Trust Signature
(tsig) [0] (and did not mark it as non-exportable) then the signature
could be found on public keyservers, and viewed in gpg with gpg
--list-sigs. A trust signature will have a number immediately to the
left of the key ID indicating the depth of the indicated trust. If your
key is DEADBEEF, and the other person is DECAFBAD, and they indicated a
depth=1 trustsig it would look like this:

test [at] fo:~ $ gpg --list-keys DEADBEEF
pub 4096R/DEADBEEF 2008-06-02 [expires: 2012-06-02]
sig 3 DEADBEEF 2008-06-02 Me Me Me! <me [at] example>
sig 1 DECAFBAD 2009-02-20 That other guy <otherguy [at] example>

note that the column with the "3" in it shows the strength of the
certification, as David Shaw mentioned -- your self-signature is
normally certified strongly, as in "i have done very careful checking".

The column with the "1" in it is the trust depth. in this case, it says
"i believe in the certifications made by this key, but i'm not willing
to accept tsigs made by this keyholder."

If you want even more details about the trust sig, you could feed your
key through "gpg --list-packets" like this:

gpg --export DEADBEEF | gpg --list-packets

You should be aware that very few people use trust signatures to
indicate ownertrust with gpg. Most people use the privately-held,
simpler trust designation.

Also, using a trustsig leaks additional information to the general
public that simple certification does not include. namely, it indicates
a statement of belief in someone's ability to make proper certifications
(and avoid improper ones), in addition to a statement of belief that the
identity of the keyholder is correctly stated.

--dkg

PS this entire message refers to ownertrust. As David Shaw has already
mentiond, this concept is entirely different from the concept of
calculated validity, or strength of identity certification.

[0] http://tools.ietf.org/html/rfc4880#section-5.2.3.13
Attachments: signature.asc (0.87 KB)


ml at mareichelt

Nov 21, 2009, 3:47 PM

Post #4 of 5 (775 views)
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Re: How to check the trust level [In reply to]

* David Shaw <dshaw [at] jabberwocky> wrote:

> If you mean the signature verification level, then it is visible in
> the --list-sigs output - 3 for "positive" verification, 2 for
> "casual" verification, and 1 for "persona" (aka didn't check)
> verification. If none of these numbers appear, it's a "generic"
> verification.

(Just to contribute to the confusion:)

That's according to the spec, but there are quite a few people out
there who do not honour the spec (for whatever reasons - not relevant
here) and have their own definition of sig levels (usually published
in their signing policy).

To sum it up, these days levels 0,2,3 are fine. 1s are a bit strange
and quite rare - I'd inquire about that kinda sig level.

--
left blank, right bald


dshaw at jabberwocky

Nov 21, 2009, 6:07 PM

Post #5 of 5 (775 views)
Permalink
Re: How to check the trust level [In reply to]

On Nov 21, 2009, at 6:47 PM, markus reichelt wrote:

> * David Shaw <dshaw [at] jabberwocky> wrote:
>
>> If you mean the signature verification level, then it is visible in
>> the --list-sigs output - 3 for "positive" verification, 2 for
>> "casual" verification, and 1 for "persona" (aka didn't check)
>> verification. If none of these numbers appear, it's a "generic"
>> verification.
>
> (Just to contribute to the confusion:)
>
> That's according to the spec, but there are quite a few people out
> there who do not honour the spec (for whatever reasons - not relevant
> here) and have their own definition of sig levels (usually published
> in their signing policy).

The spec disclaims any knowledge of the levels and leaves it up to the
individual person to decide within some (very rough) guidelines. This
is both a good and bad thing :)

It's very possible that Alice's "casual" is stronger than Baker's
"positive".

> To sum it up, these days levels 0,2,3 are fine. 1s are a bit strange
> and quite rare - I'd inquire about that kinda sig level.

#1 is very rare, since it essentially means that someone didn't check
at all. GPG actually ignores level 1 signatures by default, so that
makes them even more rare - there is little point in making one since
GPG won't even see it.

David


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