Socorro não consigo instalar o aircrack-ng

error: iw: signature from "Arch Linux ARM Build System <builder@archlinuxarm.org>" is unknown trust
:: File /var/cache/pacman/pkg/iw-5.16-1-aarch64.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]

Ao colocar y, retorna sempre.