Introduction

Prerequisites

The below scripts assume the following directory layout:

• <ca>  The directory <ca> is a placeholder. Any directory can be used.
  • create_root_ca.sh
  • create_certificate.sh
  • certs
  • csr
  • private

The sub-directories certs, csr and private will be created from the below scripts should they not exist.

Create Root CA Certificate

The first step includes to create a private key (root-ca.key) and self-signed certificate (root-ca.crt) both in PEM format. As a result the following files will be created:

• <ca>/certs/root-ca.crt
• <ca>/private/root-ca.key

  This step is performed just once. In case of repeated execution a new Root CA Certificate will be created and server certificates will have to be renewed.

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Run OpenSSL commands

#!/bin/bash

# Create Root CA private key and certificate

set -e

CA_HOME=$(dirname "$0")
CA_HOME=$(cd "${CA_HOME}" >/dev/null && pwd)

CA_CERTS=${CA_HOME}/certs
CA_PRIVATE=${CA_HOME}/private

# step 1 Generate Certificate Authority (CA) Private Key
openssl ecparam -name prime256v1 -genkey -noout -out ${CA_PRIVATE}/root-ca.key

# step 2: Generate Certificate Authority Certificate
openssl req -new -x509 -sha256 -key ${CA_PRIVATE}/root-ca.key -out ${CA_CERTS}/root-ca.crt

Create Server Certificate

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This step is performed for each server certificate that should be created:

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Replace the value of the SERVER variable with the hostname or FQDN for which the certificate should be created:

./create_certificate.sh <server-hostname>

#!/bin/bash

# Create certificate for Server Authentication and Client Authentication

set -e

CA_HOME=$(dirname "$0")
CA_HOME=$(cd "${CA_HOME}" >/dev/null && pwd)

CA_CERTS=${CA_HOME}/certs
CA_CSR=${CA_HOME}/csr
CA_PRIVATE=${CA_HOME}/private

# Specify server for which the certificate should be created
SERVER=$1somehost

# Create required sub-directories
mkdir -p ${CA_CERTS} ${CA_CSR} ${CA_PRIVATE}

# Step 1 - Generate Private Key and Certificate Signing Request
openssl req -new -config ${CA_HOME}/openssl-cert.config -extensions 'standard exts' -nodes \
    -days 7300 -newkey rsa:4096 -keyout ${CA_PRIVATE}/${SERVER}.key -out ${CA_CSR}/${SERVER}.csr

# Step 2 - Generate and Sign the Server Certificate
openssl x509 -req \
    -in ${CA_CSR}/${SERVER}.csr \
    -CA ${CA_CERTS}/root-ca.crt \
    -CAkey ${CA_PRIVATE}/root-ca.key \
    -CAcreateserial \
    -out ${CA_CERTS}/${SERVER}.crt -days 7300 \
    -extfile <(printf "subjectAltName=DNS:apmaccs,DNS:apmaccs.sos${SERVER}\nnsCertType = client, server\nkeyUsage = digitalSignature, keyEncipherment\nextendedKeyUsage = serverAuth, clientAuth\n")

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[ req ]
prompt             = no
distinguished_name = standard dn

[ standard dn ]
            commonName = apmaccs
           countryName = DE
          localityName = Berlin
      organizationName = SOS
organizationalUnitName = JS7
   stateOrProvinceName = Berlin

[ standard exts ]
extendedKeyUsage = serverAuth,clientAuth

Resources

Shell Scripts

As an alternative to running OpenSSL commands in an interactive shell scripts are provided that perform this task.

The below scripts assume the following directory layout:

• <ca>  The directory <ca> is a placeholder. Any directory can be used.
  • create_root_ca.sh
  • create_certificate.sh
  • certs
  • csr
  • private

The sub-directories certs, csr and private will be created from the below scripts should they not exist.

Create Root CA Certificate

The following files will be created:

• <ca>/certs/root-ca.crt
• <ca>/private/root-ca.key

This step is performed just once. In case of repeated execution a new Root CA Certificate will be created and server certificates will have to be renewed.

• Download: create_root_ca.sh
• The shell script is executed without arguments.

./create_root_ca.sh

Create Certificate from Shell Script

The following files will be created with <server> being a placeholder for the hostname of the indicated server.

• <ca>/certs/<server>.crt
• <ca>/certs/<server>.csr
• <ca>/private/<server>.key

This step is performed for each server certificate that should be created.

• Download: create_certificate.sh
• The shell script is executed with two arguments:
  • The DNS hostname of the server that should receive the certificate. A server can be assigned more than one DNS hostname, for example its FQDN can be different. All DNS hostnames have to be added to the certificate in order to secure connections.
  • The lifetime of the certificate specified by the number of days.

./create_certificate.sh --dns=<server-hostname>[,<server-hostname>]> --days=<number-of-days>

Links

• JS7 - How to add SSL TLS Certificates to Keystore and Truststore

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