Adding your CA to Trusted Root CA store of devices

Install the CA Cert as a trusted root CA

On Windows:

Assuming the path to your generated CA certificate as C:\ca.pem, run:

Import-Certificate -FilePath "C:\ca.pem" -CertStoreLocation Cert:\LocalMachine\Root

• Set -CertStoreLocation to Cert:\CurrentUser\Root in case you want to trust certificates only for the logged in user.

OR

In Command Prompt, run:

certutil.exe -addstore root C:\ca.pem

• certutil.exe is a built-in tool (classic System32 one) and adds a system-wide trust anchor.

On Android:

The exact steps vary device-to-device, but here is a generalised guide:

1. Open Phone Settings
2. Locate Encryption and Credentials section. It is generally found under Settings > Security > Encryption and Credentials
3. Choose Install a certificate
4. Choose CA Certificate
5. Locate the certificate file ca.pem on your SD Card/Internal Storage using the file manager.
6. Select to load it.
7. Done!

On Debian & Derivatives (Ubuntu):

• Move the CA certificate (ca.pem) into /usr/local/share/ca-certificates/ca.crt.
• Update the Cert Store with:

sudo update-ca-certificates

Refer to the documentation here and here.

On Fedora

• Move the CA certificate (ca.pem) to /etc/pki/ca-trust/source/anchors/ca.pem or /usr/share/pki/ca-trust-source/anchors/ca.pem
• Now run (with sudo if necessary):

update-ca-trust

Refer the documentation here.

On Arch

System-wide – Arch(p11-kit) (From arch wiki)

• Run (As root)

trust anchor --store myCA.crt

• The certificate will be written to /etc/ca-certificates/trust-source/myCA.p11-kit and the "legacy" directories automatically updated.
• If you get "no configured writable location" or a similar error, import the CA manually:
• Copy the certificate to the /etc/ca-certificates/trust-source/anchors directory.
• and then

update-ca-trust

wiki page here