invalid or corrupted (all new) packages (PGP signature)

[serons]

After accepting the following line during a sync update I get the error below on all package updates.
$this->bbcode_second_pass_code('', ':: Import PGP key 4096R/2BDBE6A6, "Arch Linux ARM Build System <builder@archlinuxarm.org>", created: 2014-01-18? [Y/n] ')
$this->bbcode_second_pass_code('', 'error: glibc: signature from "Arch Linux ARM Build System <builder@archlinuxarm.org>" is unknown trust
:: File /var/cache/pacman/pkg/glibc-2.18-12.1-armv6h.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n] ')
In /etc/pacman.conf I've got $this->bbcode_second_pass_code('', '[options]
SigLevel = Optional')
How does one fix this?

[moonman]

viewtopic.php?f=3&t=6745

[kmihelich]

You have to install the keyring before you enable signature checking.

[Lekensteyn]

This works for me:

$this->bbcode_second_pass_code('', '# pacman-key --lsign-key 2BDBE6A6
-> Locally signing key 2BDBE6A6...
==> Updating trust database...
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 1 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1 valid: 1 signed: 0 trust: 1-, 0q, 0n, 0m, 0f, 0u
')

I then installed archlinuxarm-keyring and then the upgrade could continue (my previous update was 7 January 2014).