[Mageia-dev] PGP keys and package signing

[Dick Gevers]

On Tue, 01 Feb 2011 00:15:36 +0100, Michael Scherer wrote about Re:
[Mageia-dev] PGP keys and package signing:

>Le lundi 31 janvier 2011 à 21:49 +0000, Dick Gevers a écrit :
>> On Mon, 31 Jan 2011 17:18:25 +0100, Michael Scherer wrote about Re:
>> [Mageia-dev] PGP keys and package signing:
>> 
>> >The problem is not leaking the key, it is about cryptographic attacks
>> >about older keys.
>> >
>> >If in 10 years, there is some technology that allows people to get our
>> >private key by bruteforce on the public one
>> 
>> You can never ever obtain the private key from the public one, that is
>> impossible. It can only be compromised if someone looses the private key
>> plus the password is cracked.
>
>Some secure systems have been seen compromised ( like
>http://www.win.tue.nl/hashclash/rogue-ca/, who explain how the whole SSL
>business was compromised 2 years ago, or see the GSM being cracked at
>this year 27C3 ). 
>
>And Debian also got ride of older vulnerable gpg keys ( see
>http://lists.debian.org/debian-devel-announce/2010/04/msg00018.html and
>http://lists.debian.org/debian-devel-announce/2010/09/msg00003.html ),
>so I would not be so optimistic about the "never".
>
>Technically, MD5 should not have been reversible, but see how easy it is
>using a rainbow table. Granted, that's a 20 year protocol, but that's
>still widely used in lots of software.

Sorry, but I am not convinced: the gpg key we are talking about consists of
2 parts: the private key is separate from the public key, or signing key.
The signing key is a separate or subkey and does not contain any part of the
private key. So you can throw any amount of computing power at it, but
there is nothing inside the public key that will enable the rebuilding of
the private key from it.

Ciao,
=Dick Gevers=