From your Letsencrypt ACME host copy fullchain.cert and the private key file

scp fullchain.cert openhab.mife.ca.key openhab.mife.ca:/root/

** Note: you can install openjdk jre-headless package to install keytool **

From your openhab host create a new keystore

Do this from your working directory. Replace pass:openhab with your own password.

openssl pkcs12 -export -in fullchain.cer -inkey openhab.mife.ca.key -out keystore -passout pass:openhab -name mykey

Configure keystore password in Openhab

My openhab installation had a blank keystore password, which no longer supported. I had to update /var/lib/openhab2/etc/custom.system.properties file and add jetty.ssl.password line with my password

karaf.name=openhab
karaf.local.user=openhab
mdnsName=openhab
smarthome.servicepid=org.openhab
smarthome.servicecfg=${openhab.runtime}/services.cfg
smarthome.userdata=${openhab.userdata}
smarthome.configdir=${openhab.conf}
org.quartz.properties=${openhab.runtime}/etc/quartz.properties
jetty.keystore.path=${openhab.userdata}/etc/keystore
jetty.truststore.path=${openhab.userdata}/etc/keystore
jetty.ssl.password=openhab
equinox.ds.block_timeout=240000
equinox.scr.waitTimeOnBlock=60000

Replace keystore file

Copy keystore from your working directory to destination, first make a backup

cp /var/lib/openhab2/etc/keystore ./keystore.bak
cp ./keystore /var/lib/openhab2/etc/keystore


### Restart Openhab service
```sh
systemctl restart openhab2.service