SSL/TLS Network Certificate Authority and Host Certificate creation instructions

Create SSL/TLS Certificate Authority and host Certificates for your local network.

Network Certificate Authority and Host Certificate creation instructions
- Certificates
  - Create the local network Certificate Authority
  - Create public and private keys for each LAN host
- Update clients
  - Update Certificate Authority list on Windows hosts

Derived from Create Your Own SSL Certificate Authority for Local HTTPS Development ^archived

Certificates

Create the local network Certificate Authority

In this example, the local local network suffix is .car.

Commands

LLN="car"
CA="${LLN}-CA"
openssl genrsa -des3 -out "${CA}.key" 2048
openssl req -x509 -new -nodes -key "${CA}.key" -sha256 -days 1825 -out "${CA}.pem"

Looks like

$ openssl genrsa -des3 -out car-CA.key 2048
Enter pass phrase for car-CA.key:

$ openssl req -x509 -new -nodes -key car-CA.key -sha256 -days 1825 -out car-CA.pem
Enter pass phrase for car-CA.key:
Country Name (2 letter code) [AU]:US
State or Province Name (full name) [Some-State]:My State
Locality Name (eg, city) []:My City
Organization Name (eg, company) [Internet Widgits Pty Ltd]:car netwerk
Organizational Unit Name (eg, section) []:head honcho
Common Name (e.g. server FQDN or YOUR name) []:server1.car
Email Address []:me+car@email.com

Record the certificate passphrase somewhere secure.

Should now have three new files

car-CA.key
car-CA.pem
car-CA.srl

Create public and private keys for each LAN host

In this example, create a certificate for host1.car of the car network using car-CA

Commands

LLN="car"; CA="${LLN}-CA"; H="host1"; HN="${H}.${LLN}"
openssl genrsa -out "${HN}.key" 2048
openssl req -new -key "${HN}.key" -out "${HN}.csr"
edit "${HN}.ext"
openssl x509 -req -in "${HN}.csr" -CA "${CA}.pem" -CAkey "${CA}.key" -CAcreateserial -out "${HN}.crt" -days 1825 -sha256 -extfile "${HN}.ext"

Looks like

$ openssl genrsa -out host1.car.key 2048
Generating RSA private key, 2048 bit long modulus

$ openssl req -new -key host1.car.key -out host1.car.csr
Country Name (2 letter code) [AU]:US
State or Province Name (full name) [Some-State]:My State
Locality Name (eg, city) []:My City
Organization Name (eg, company) [Internet Widgits Pty Ltd]:car netwerk
Organizational Unit Name (eg, section) []:Some Service
Common Name (e.g. server FQDN or YOUR name) []:host1.car
Email Address []:me+host1@email.com
A challenge password []:pa55w0rd
An optional company name []:

Manually create a .ext file to allow multiple DNS names to be assocaited with the host via [alt_names] section.
This will allow certificate checks for the bare name host1, and the FQDN host1.car.

$ echo '\
authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names
[alt_names]
DNS.1 = host1
DNS.2 = host1.car' > host1.car.ext

Create the host1 signed certificate. This will require the Certificate Authority passphrase to be entered.

$ openssl x509 -req \
                 -in host1.car.csr \
                 -CA car-CA.pem \
                 -CAkey car-CA.key \
                 -CAcreateserial \
                 -out host1.car.crt \
                 -days 1825 \
                 -sha256 \
                 -extfile host1.car.ext
Signature ok
subject=C = US, ST = My State, L = My City, O = car network, OU = Some Org, CN = host1.car, emailAddress = "me+host1@email.com"
Getting CA Private Key
Enter pass phrase for car-CA.key:

Should now have four new files:

host1.car.crt
host1.car.csr
host1.car.ext
host1.car.key

Only the files .crt, .key will be used by TLS-based services. The .csr and .ext are not needed.

Update clients

Update Certificate Authority list on Windows hosts

Derived from How to manage Trusted Root Certificates in Windows 10 ^archived.

Run Manage User Certificates
Navigate to Certificates → Trusted Root Certification Authorities → Certificates
Import car.pem The Import Wizard does not have a *.pem selector. Use the *.* selector and then select car-CA.pem.

From the linked article, I skipped changing the Local Computer Policy (per the Group Policy Snap-in).

Test with the Edge web browser.