Generates a self-signed certificate for Mosquitto

generate-CA.sh

#!/bin/bash
#(@)generate-CA.sh - Create CA key-pair and server key-pair signed by CA

# Copyright (c) 2013 Jan-Piet Mens <jpmens()gmail.com>
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
# 1. Redistributions of source code must retain the above copyright notice,
#    this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. Neither the name of mosquitto nor the names of its
#    contributors may be used to endorse or promote products derived from
#    this software without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

#
# Usage:
#	./generate-CA.sh		creates ca.crt and server.{key,crt}
#	./generate-CA.sh hostname	creates hostname.{key,crt}
#
# Set the following optional environment variables before invocation
# to add the specified IP addresses and/or hostnames to the subjAltName list
# These contain white-space-separated values
#
#	IPLIST="172.13.14.15 192.168.1.1"
#	HOSTLIST="a.example.com b.example.com"

set -e

export LANG=C

host=$(hostname -f)
if [ -n "$1" ]; then
	host="$1"
fi

[ -z "$USER" ] && USER=root

DIR=${TARGET:='.'}
# A space-separated list of alternate hostnames (subjAltName)
# may be empty ""
ALTHOSTNAMES=${HOSTLIST}
ALTADDRESSES=${IPLIST}
CA_ORG='/O=Meh/emailAddress=nobody@example.net'
CA_DN="/CN=An MQTT broker${CA_ORG}"
CACERT=${DIR}/ca
SERVER="${DIR}/${host}"
SERVER_DN="/CN=${host}$CA_ORG"
keybits=2048
openssl=$(which openssl)
MOSQUITTOUSER=${MOSQUITTOUSER:=$USER}

function maxdays() {
	nowyear=$(date +%Y)
	years=$(expr 2032 - $nowyear)
	days=$(expr $years '*' 365)

	echo $days
}

function getipaddresses() {
	/sbin/ifconfig |
		grep -v tunnel |
		sed -En '/inet6? /p' |
		sed -Ee 's/inet6? (addr:)?//' |
		awk '{print $1;}' |
		sed -e 's/[%/].*//' |
		egrep -v '(::1|127\.0\.0\.1)'	# omit loopback to add it later
}


function addresslist() {

	ALIST=""
	for a in $(getipaddresses); do
		ALIST="${ALIST}IP:$a,"
	done
	ALIST="${ALIST}IP:127.0.0.1,IP:::1,"

	for ip in $(echo ${ALTADDRESSES}); do
		ALIST="${ALIST}IP:${ip},"
	done
	for h in $(echo ${ALTHOSTNAMES}); do
		ALIST="${ALIST}DNS:$h,"
	done
	ALIST="${ALIST}DNS:localhost"
	echo $ALIST

}

days=$(maxdays)

if [ -n "$CAKILLFILES" ]; then
	rm -f $CACERT.??? $SERVER.??? $CACERT.srl
fi

if [ ! -f $CACERT.crt ]; then
	# Create un-encrypted (!) key
	$openssl req -newkey rsa:${keybits} -x509 -nodes -days $days -extensions v3_ca -keyout $CACERT.key -out $CACERT.crt -subj "${CA_DN}"
	echo "Created CA certificate in $CACERT.crt"
	$openssl x509 -in $CACERT.crt -nameopt multiline -subject -noout

	chmod 400 $CACERT.key
	chmod 444 $CACERT.crt
	chown $MOSQUITTOUSER $CACERT.*
	echo "Warning: the CA key is not encrypted; store it safely!"
fi

if [ ! -f $SERVER.key ]; then
	echo "--- Creating server key and signing request"
	$openssl genrsa -out $SERVER.key $keybits
	$openssl req -new \
		-out $SERVER.csr \
		-key $SERVER.key \
		-subj "${SERVER_DN}"
	chmod 400 $SERVER.key
	chown $MOSQUITTOUSER $SERVER.key
fi

if [ -f $SERVER.csr -a ! -f $SERVER.crt ]; then

	# There's no way to pass subjAltName on the CLI so
	# create a cnf file and use that.

	CNF=`mktemp /tmp/cacnf.XXXXXXXX` || { echo "$0: can't create temp file" >&2; exit 1; }
	sed -e 's/^.*%%% //' > $CNF <<\!ENDconfig
	%%% [ JPMextensions ]
	%%% basicConstraints        = critical,CA:false
	%%% nsCertType              = server
	%%% keyUsage                = nonRepudiation, digitalSignature, keyEncipherment
	%%% nsComment               = "Broker Certificate"
	%%% subjectKeyIdentifier    = hash
	%%% authorityKeyIdentifier  = keyid,issuer:always
	%%% subjectAltName          = $ENV::SUBJALTNAME
	%%% # issuerAltName           = issuer:copy
	%%% certificatePolicies     = ia5org,@polsection
	%%% 
	%%% [polsection]
	%%% policyIdentifier	    = 1.3.5.8
	%%% CPS.1		    = "http://localhost"
	%%% userNotice.1	    = @notice
	%%% 
	%%% [notice]
	%%% explicitText            = "This CA is for a local MQTT broker installation only"
	%%% organization            = "Meh"
	%%% noticeNumbers           = 1


!ENDconfig

	SUBJALTNAME="$(addresslist)"
	export SUBJALTNAME		# Use environment. Because I can. ;-)

	echo "--- Creating and signing server certificate"
	$openssl x509 -req \
		-in $SERVER.csr \
		-CA $CACERT.crt \
		-CAkey $CACERT.key \
		-CAcreateserial \
		-CAserial "${DIR}/ca.srl" \
		-out $SERVER.crt \
		-days $days \
		-extfile ${CNF} \
		-extensions JPMextensions

	rm -f $CNF
	chmod 444 $SERVER.crt
	chown $MOSQUITTOUSER $SERVER.crt
fi