Pacman: File is corrupted error

[theoverthere]

I did a successful 'pacman -Syu' and then when I tried to install the package valgrind I got a message that suggested I do a 'pacman-key --init'. I did that and got:

$this->bbcode_second_pass_code('', 'gpg: /etc/pacman.d/gnupg/trustdb.gpg: trustdb created
gpg: no ultimately trusted keys found
gpg: starting migration from earlier GnuPG versions
gpg: porting secret keys from '/etc/pacman.d/gnupg/secring.gpg' to gpg-agent
gpg: migration succeeded
gpg: Generating pacman keyring master key...
gpg: key 462C3D596C948B13 marked as ultimately trusted
gpg: directory '/etc/pacman.d/gnupg/openpgp-revocs.d' created
gpg: revocation certificate stored as '/etc/pacman.d/gnupg/openpgp-revocs.d/0BF504BD97909DF038E3A87F462C3D596C948B13.rev'
gpg: Done
==> Updating trust database...
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u')
I currently get the following error when I try to install valgrind with 'pacman -S valgrind':
$this->bbcode_second_pass_code('', 'resolving dependencies...
looking for conflicting packages...

Packages (1) valgrind-3.13.0-7

Total Download Size: 22.98 MiB
Total Installed Size: 133.27 MiB

:: Proceed with installation? [Y/n] y
:: Retrieving packages...
valgrind-3.13.0-7-armv7h 23.0 MiB 1994K/s 00:12 [############################] 100%
(1/1) checking keys in keyring [############################] 100%
(1/1) checking package integrity [############################] 100%
error: valgrind: signature from "Arch Linux ARM Build System <builder@archlinuxarm.org>" is unknown trust
:: File /var/cache/pacman/pkg/valgrind-3.13.0-7-armv7h.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n] y
error: failed to commit transaction (invalid or corrupted package (PGP signature))
Errors occurred, no packages were upgraded.')
I tried some methods that I found on the archlinux forum to no avail: I tried to install rchlinux-keyring but I get the same error minus the valgrind info when I try to. I tried 'pacman-key --refresh-keys'. The following is the output to 'pacman-key --list-sigs Arch Linux ARMBuild System':
$this->bbcode_second_pass_code('', 'pub rsa4096 2014-01-18 [SC]
68B3537F39A313B3E574D06777193F152BDBE6A6
uid [ unknown] Arch Linux ARM Build System <builder@archlinuxarm.org>
sig 1BB89C0602367449 2018-01-16 [User ID not found]
sig BF7EEF7A9C6B5765 2014-01-18 [User ID not found]
sig BC704E86B823CD25 2014-01-18 [User ID not found]
sig B55C5315DCD9EE1A 2014-01-18 [User ID not found]
sig 2 AB4311039017FB32 2017-09-25 [User ID not found]
sig 3 77193F152BDBE6A6 2014-01-18 Arch Linux ARM Build System <builder@archlinuxarm.org>
sub rsa4096 2014-01-18 [E]
sig 1BB89C0602367449 2018-01-16 [User ID not found]
sig 77193F152BDBE6A6 2014-01-18 Arch Linux ARM Build System <builder@archlinuxarm.org>')
What should I do?

[cyberhoffman]

$this->bbcode_second_pass_quote('', 'W')hat should I do?

[theoverthere]

Thanks so much cyberhoffman. Much appreciated.