[pkg-gnupg-maint] Bug#802100: gnupg should fetch keys using hkps by default

[Strelok]

On Sat, 17 Oct 2015 15:31:22 +0100 Antoine Amarilli <a3nm at a3nm.net> wrote:
> Package: gnupg
> Version: 1.4.19-5
> Severity: wishlist
>
> Dear Maintainer,
>
> By default, gpg requests keys using HKP server <keys.gnupg.net>. This allows a
> passive attacker to obtain information about the keys requested by the user,
> which may be harmful in terms of privacy.
And HKP server requested to verify .sign file downloaded from
cdimage.debian.org. Let's assume active attack like this:
Step 1) You try download iso file from cdimage.debian.org, but man in
middle redirect you to very.evil.org server.
Step 2) You download files from very.evil.org, compare hash to
SHA256SUMS file, and check SHA256SUMS file through "gpg --verify
SHA256SUMS.sign". Then, you see some like "Signature made Wed 11 Nov
2015 20:08:10 GMT using DSA key ID 12345678 Can't check signature:
public key not found".
Step 3) You run "gpg --recv 12345678"... And yes, man in middle
redirected you to keyserver.very.evil.org with false public key.
Step 4) You run "gpg --verify SHA256SUMS.sign" one more time... And
see "Good signature from evil hacker", because you get false signature
with false public key.
And this is very big hole in security.