Hello, Looks like the key used to sign the kup 0.9.0 tarball isn't available on public servers: # gpg --search-keys C6C10CB4B8F6556AB08F0CEE8E0D9EA66ED30380 gpg: data source: https://hkps.pool.sks-keyservers.net:443 gpg: key "C6C10CB4B8F6556AB08F0CEE8E0D9EA66ED30380" not found on keyserver Was it uploaded? Christophe