Re: [Sks-devel] "quality" of keyservers offering hkps

[Kristian Fiskerstrand]

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On 08/14/2014 04:36 PM, Pete Stephenson wrote:
> On 8/14/2014 4:06 PM, Kristian Fiskerstrand wrote:
>> On 08/14/2014 04:04 PM, Pete Stephenson wrote:
>>> My (albeit limited) understanding is that SKS is an append-only
>>>  system, and that it is not possible to remove key packets that
>>> are already on the servers.
>> 
>>> Wouldn't a bad guy: a. Need the private key to edit self-signed
>>>  elements, like revocation signatures?
>> 
>> No, you can drop the full signature or just use a copy of the key
>> from before reovcation was appended.
>> 
>>> b. Be unable to remove the revocation signature, as SKS servers
>>> are append-only?
>> 
>> Not in a MITM scenario where you don't really talk with SKS in
>> the first place, hence a very good reason for HKPS in the first
>> place.
> 
> [re-sending to list, as I inadvertently sent this response directly
> to Kristian]
> 
> Ok. Just for clarity, these attacks are only possible in a MITM 
> scenario, correct?
> 
> Am I correct in my understanding that the bad guy could only do
> the packet stripping if they were MITMing the client and presented
> the user with the desired key sans the revocation signature?
> 
> That is, the bad guy can't upload the key sans revocation signature
> to the actual pool, since the pool is append-only and so the
> revocation signature would not be removed from the pool.
> 

Affirmative. Or DoSing the client so that no request for update of the
key containing the revocation certificate is in place. Or the user's
operational security parameters are insufficient at updating certs
regularly.

- -- 
- ----------------------------
Kristian Fiskerstrand
Blog: http://blog.sumptuouscapital.com
Twitter: @krifisk
- ----------------------------
Public OpenPGP key 0xE3EDFAE3 at hkp://pool.sks-keyservers.net
fpr:94CB AFDD 3034 5109 5618 35AA 0B7F 8B60 E3ED FAE3
- ----------------------------
Fabricando fit faber
Practice makes perfect
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