Re: [Sks-devel] Possible solution to "delete" keys

[Kristian Fiskerstrand]

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On 10/29/2013 10:59 PM, dirk astrath wrote:
> Hello again ;-)
> 
> I understand the issue, that keys shouldn't be deleted from the 
> database. They should be revoked only and kept in the database.
> 

...

> 
> I suggest to "sign" the "to-be-deleted"-key with a special
> signature, which causes the personal data of this key not to be
> displayed.
> 

Some off-the-top-of-my-head issues with this approach;
        (i) Who would determine who should have such delete capabilities? Is
there any reason for key server operators to have any more "power"
than anyone else?
        (ii) If someone is determined as such a "key deleter"; is there legal
culpability possibilities for keys not having been deleted
        (iii) SKS doesn't implement crypto, doing so on a keyserver will
massively increase the resource requirements
        (iv) the data is still in the keystore and will have to be
synchronized, anyone mallicious will be able to get the keydump
directly and extract the data.

> In this case we have 4 possible answers for a key if searching for
> the Key-ID:
> 

...

> ... and new:
> 
> (4)   Key is deleted: Show key-id only and red marker "revoked"
> 

(i) This can be used as an attack vector to upload a forged key and
delete the old one. (ii) Simply displaying revoked doesn't mean
anything for OpenPGP implementations

> To go a step deeper:
> 
> Many users created a test/demo-key a long time ago and 
> forgot/deleted/... the private key or private-key-passphrase.
> Since it's impossible to delete (or even revoke) the old keys,
> these keys may still be used to encrypt mails to the user (which
> may never be able to decrypt it). If the personal data from these
> old keys can be hidden (=not displayed to the user or
> PGP/GnuPG-software) only the active and revoked keys will be used.
> 
> (Every now and then i get the question from users: "which key
> should i use to send a mail to you ... if I'm unsure, i use
> unencrypted mail").
> 

...


> 
> We have to decide the details of the procedure to mark a key as 
> deleted in the database like "two or three sks-operators have to
> be sure", "email-verification", "can be deleted only, if an
> encrypted mail has been sent" etc. ...
> 

A key isn't less valid even if a domain name expire and a new user
takes control of that domain.

- -- 
- ----------------------------
Kristian Fiskerstrand
Blog: http://blog.sumptuouscapital.com
Twitter: @krifisk
- ----------------------------
Public PGP key 0xE3EDFAE3 at hkp://pool.sks-keyservers.net
fpr:94CB AFDD 3034 5109 5618 35AA 0B7F 8B60 E3ED FAE3
- ----------------------------
Bene diagnoscitur, bene curatur
Something that is well diagnosed can be cured well
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