On Tue, Mar 22, 2016 at 2:45 PM, Björn Persson <Bjorn@rombobjörn.se> wrote:
>
> Till Maas wrote:
> > I guess it might even make the new hotness do scratch builds with
> > verified tarballs, since iirc it updates both the tarball and the
> > signature and then %prep makes sure that they are verified.
>
> I suppose so, at least if the key is specified as only a filename. What
> will it do if a URL to the key is provided, and the key at that location
> has been modified? Will it replace the key with the modified one in the
> scratch build, or will it leave the key alone when there is no version
> number in the filename?

If Werner Koch is willing to make changes to benefit this type of use
case, I don't suppose he could be persuaded to define a canonical,
reasonably compact fingerprint format?

$ gpg --verify-by-fingerprint "gpg-ecdsa-nfakjwejfhasasfewiahcalkweec"
filename filename.sig [optional path to keyring or whatever if not
embedded in the sig]

would be quite handy.

256 bits of fingerprint would be sufficient for the forseeable future
against anything except multiple-target quantum attacks.  With
signature schemes like ECDSA, simply encoding the literal public key
would work fine, too.

<not-yet-relevant>Off the top of my head, a multiple-target quantum
attack involves finding any of 2^t needles in a haystack of size 2^b,
for a probability of 2^(t-b) that any given needle wins.  Using a
practical upper bound of t=128 and requiring that the adversary spend
2^128 effort on an attack gives t-b ~ 256 or b ~ 384 bits for security
against Grover-style attacks.

Of course, trying to defend against that attack using 384-bit
fingerprints over ECDSA keys is totally pointless.  The world should
seriously consider switching to SPHINCS or similar for software
verification.
</not-yet-relevant>

>
> Björn Persson
>
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