I configure successfully the ddns script for no-ip.com.
Making a little debug with this command
/usr/lib/ddns/dynamic_dns_updater.sh -v 2 start
I see the command use curl
/usr/bin/curl -RsS -o /var/run/ddns/myddns_ipv4.dat --stderr /var/run/ddns/myddns_ipv4.err --interface pppoe-wan --noproxy '*' 'http://myusername:pass@siteupdate/nic/update?hostname=myhostname&myip"
My question is: why don't use https? Is possible to force https?