create-self-signed-certs.sh

#!/usr/bin/env bash
# Define where to store the generated certs and metadata.
DIR="$(pwd)/.certs"

# Optional: Ensure the target directory exists and is empty.
rm -rf "${DIR}"
mkdir -p "${DIR}"

# Create the openssl configuration file. This is used for both generating
# the certificate as well as for specifying the extensions. It aims in favor
# of automation, so the DN is encoding and not prompted.
cat > "${DIR}/openssl.cnf" << EOF
[req]
default_bits = 2048
encrypt_key  = no # Change to encrypt the private key using des3 or similar
default_md   = sha256
prompt       = no
utf8         = yes
# Speify the DN here so we aren't prompted (along with prompt = no above).
distinguished_name = req_distinguished_name
# Extensions for SAN IP and SAN DNS
req_extensions = v3_req
# Be sure to update the subject to match your organization.
[req_distinguished_name]
C  = UE
ST = Bruxelas
L  = Bruxelas
O  = OCARIoT CA
CN = localhost
# Allow client and server auth. You may want to only allow server auth.
# Link to SAN names.
[v3_req]
basicConstraints     = CA:FALSE
subjectKeyIdentifier = hash
keyUsage             = digitalSignature, keyEncipherment
extendedKeyUsage     = clientAuth, serverAuth
subjectAltName       = @alt_names
# Alternative names are specified as IP.# and DNS.# for IP addresses and
# DNS accordingly.
[alt_names]
IP.1  = 127.0.0.1
DNS.1 = localhost
EOF

# Create the certificate authority (CA). This will be a self-signed CA, and this
# command generates both the private key and the certificate. You may want to
# adjust the number of bits (4096 is a bit more secure, but not supported in all
# places at the time of this publication).
#
# To put a password on the key, remove the -nodes option.
#
# Be sure to update the subject to match your organization.
openssl req \
  -new \
  -newkey rsa:2048 \
  -days 365 \
  -nodes \
  -x509 \
  -subj "/C=US/ST=Bruxelas/L=Bruxelas/O=OCARIoT CA/CN=localhost" \
  -keyout "${DIR}/ca.key" \
  -out "${DIR}/ca.crt"
# For each server/service you want to secure with your CA, repeat the
# following steps:

# Generate the private key for the service. Again, you may want to increase
# the bits to 4096.
openssl genrsa -out "${DIR}/server.key" 2048

# Generate a CSR using the configuration and the key just generated. We will
# give this CSR to our CA to sign.
openssl req \
  -new -key "${DIR}/server.key" \
  -out "${DIR}/server.csr" \
  -config "${DIR}/openssl.cnf"

# Sign the CSR with our CA. This will generate a new certificate that is signed
# by our CA.
openssl x509 \
  -req \
  -days 365 \
  -in "${DIR}/server.csr" \
  -CA "${DIR}/ca.crt" \
  -CAkey "${DIR}/ca.key" \
  -CAcreateserial \
  -extensions v3_req \
  -extfile "${DIR}/openssl.cnf" \
  -out "${DIR}/server.crt"

# (Optional) Remove unused files at the moment
rm -rf "${DIR}/ca.key" "${DIR}/ca.srl" ".srl" "${DIR}/server.csr" "${DIR}/openssl.cnf"