Migrate PKI to SHA256 signatures Howto

  1. Migrate PKI to SHA256 signatures Howto
    1. Summary
    2. Background
    3. Change the default
    4. Re-sign CA cert
    5. Re-sign certs for engine side entities
      1. Choose entities to re-sign
      2. Enter Maintenance
      3. Re-sign
      4. Restart services
      5. Exit maintenance
      6. Reconnect to web admin
    6. Enroll Certificates for hosts
    7. Verify


oVirt 4.1, on new setups, creates PKI infrastructure that uses SHA256 signatures.

Existing setups upgraded to 4.1 do not currently have PKI migrated.

This Howto explains how to manually migrate the PKI of such setups to use SHA256 signatures.


Previous versions of oVirt used SHA-1 for signatures of SSL certificates created by the internal CA. This is no longer considered secure, see e.g. Firefox Chrom Edge/IE or shattered.io.

See Features/PKI for general details about PKI in oVirt.

If you are worried only by a recent browser warning about or rejecting your SHA-1-signed certificate, it might be enough to only re-sign the apache certificate, or only the CA+apache certificates. This procedure was only tested currently in its entirety.

Change the default

This step is not needed on >= 4.1.

On < 4.1, upgrading to a newer < 4.1 version (e.g. 4.0.6 to 4.0.7) might revert this change, so you need to repeat it per each upgrade until 4.1.

On the engine machine, run these commands:

# Backup exiting conf
cp -p /etc/pki/ovirt-engine/openssl.conf /etc/pki/ovirt-engine/openssl.conf."$(date +"%Y%m%d%H%M%S")"

# Edit it to default to SHA256
sed -i 's/^default_md = sha1/default_md = sha256/' /etc/pki/ovirt-engine/openssl.conf

Re-sign CA cert

If you only use this procedure because your browser warns/rejects, then it might be enough to skip this part. If your browser requires both the CA cert and the https cert to have SHA256 signatures, you have to complete it.

On the engine machine, run these commands:

# Backup CA cert
cp -p /etc/pki/ovirt-engine/private/ca.pem /etc/pki/ovirt-engine/private/ca.pem."$(date +"%Y%m%d%H%M%S")"

# Create a new cert into ca.pem.new
openssl x509 -signkey /etc/pki/ovirt-engine/private/ca.pem -in /etc/pki/ovirt-engine/ca.pem -out /etc/pki/ovirt-engine/ca.pem.new -days 3650 -sha256

# Replace the existing with the new one
/bin/mv /etc/pki/ovirt-engine/ca.pem.new /etc/pki/ovirt-engine/ca.pem

Re-sign certs for engine side entities

Choose entities to re-sign

Decide what you want, among the options below:

If only apache httpd (for browsers that reject SHA1 signatures), run:


If also the engine cert:

names="apache engine"

If all normally-existing entities:

names="engine apache websocket-proxy jboss imageio-proxy"

If you replaced the https cert with a cert signed by a 3rd party, you should not include “apache” in above - e.g. use one of:

# or
names="engine websocket-proxy jboss imageio-proxy"

Enter Maintenance

If this is a self-hosted-engine, move it to global maintenance.


Run this (in the same terminal of previous subsection above):

for name in $names; do
	subject="$(openssl x509 -in /etc/pki/ovirt-engine/certs/"${name}".cer -noout -subject | sed 's;subject= \(.*\);\1;')"
	/usr/share/ovirt-engine/bin/pki-enroll-pkcs12.sh --name="${name}" --password=mypass --subject="${subject}" --keep-key

Restart services

If you included apache:

systemctl restart httpd

If you included engine:

systemctl restart ovirt-engine

If you included ovirt-websocket-proxy/ovirt-imageio-proxy:

systemctl restart ovirt-websocket-proxy

systemctl restart ovirt-imageio-proxy

Exit maintenance

If this is a self-hosted-engine, exit global maintenance.

Reconnect to web admin

Your browser will likely refuse to continue working with the web admin ui. You might need to restart it and/or remove the engine cert and/or engine ca cert.

In my own case I unchecked “Permanently store this exception” when I first logged in, and after restarting httpd the browser showed an error about using the same serial number. Restarting the browser was enough to login again.

Enroll Certificates for hosts

For all of your hosts, one host at a time, using the web admin ui:

  • Set it to Maintenance

  • Choose “Enroll Certificates”

  • Activate


You can do this step at any time, also before starting this procedure.

Certs that use SHA1 will show as having ‘sha1WithRSAEncryption’. Certs that use SHA256 will show as having ‘sha256WithRSAEncryption’.

On engine machine:

openssl x509 -in /etc/pki/ovirt-engine/ca.pem -text | grep Signature
for name in engine apache websocket-proxy jboss imageio-proxy; do echo $name:; openssl x509 -in /etc/pki/ovirt-engine/certs/"${name}".cer -text | grep Signature; done

On hosts:

openssl x509 -in /etc/pki/vdsm/certs/vdsmcert.pem -text | grep Signature
openssl x509 -in /etc/pki/vdsm/certs/cacert.pem -text | grep Signature