Introduction

SSL/TLS Certificates are used to secure HTTP connections between JOC Cockpit, Controller and Agents, for example JS7 - JOC Cockpit HTTPS Connections.

Users can choose one of the approachs specified with RFC5280:

• Self-issued Certificates are created individually per user and are not applicable within reasonable effort for deploying individual certificate files to JS7 products.
• Private CA-signed Certificates are issued by users who operate their own Private Certificate Authority (CA).
• Public CA-signed Certificates are issued by a trusted Certificate Authority (CA) that validates the domain owner. They are not created by users but are purchased from the trusted CA and are not in scople of this article.

There is no difference in using a Private CA or Public CA concerning functionality of X.509 certificates, usage for Server Authentication / Client Authentication, or security of connections. The only difference is that users trust the Private CA that they set up on their own.

Examples in the article make use of JS7 Release 2.7.2, OpenSSL 1.1.1k  FIPS 25 Mar 2021 for Unix and OpenSSL 3.1.4 24 Oct 2023 for Windows. OpenSSL ships with Linux & other Unix OS and is available for Windows.

Setting up the Private CA

Creating the Private Key and Certificate Signing Request

Users have the option to use ECDSA or RSA for the encryption type applied to the Private Key.

Users can run the following commands from the shell and replace the value of the ca_key_name environment variable with a name of their choice that is used when creating related files.

Using ECDSA Encryption

# Specify key name used for file names
ca_key_name=root-ca

# Create Private Key
openssl ecparam -genkey -name secp384r1 -out ${ca_key_name}.key

# Create Certificate Signing Request
openssl req -new -sha512 -nodes \
    -key ${ca_key_name}.key \
    -out ${ca_key_name}.csr \
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=${ca_key_name}"

@rem Specify key name used for file names
set ca_key_name=root-ca
 
@rem Create Private Key
openssl ecparam -genkey -name secp384r1 -out %ca_key_name%.key
 
@rem Create Certificate Signing Request 
openssl req -new -sha512 -nodes ^
    -key %ca_key_name%.key ^
    -out %ca_key_name%.csr ^
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=%ca_key_name%"

Using RSA Encryption

# Specify key name used for file names
ca_key_name=root-ca

# Create Private Key and Certificate Signing Request
openssl req -new -newkey rsa:4096 -sha256 -nodes \
    -keyout ${ca_key_name}.key \
    -out ${ca_key_name}.csr \
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=${ca_key_name}"

@rem Specify key name used for file names
set ca_key_name=root-ca
 
@rem Create Private Key and Certificate Signing Request
openssl req -new -newkey rsa:4096 -sha256 -nodes ^
    -keyout %ca_key_name%.key ^
    -out %ca_key_name%.csr ^
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=%ca_key_name%"

Creating the CA Certificate

Steps include to create the root-ca.crt Private CA-signed Certificate file in PEM format.

Users can run the following commands from the shell and replace the value of the ca_key_name environment variable with a name of their choice that is used when creating related files.

# Specify key name used for file names
ca_key_name=root-ca

# Create Certificate
openssl x509 -req -sha512 -days 7305 \
    -signkey ${ca_key_name}.key \
    -in ${ca_key_name}.csr \
    -out ${ca_key_name}.crt \
    -extfile <(printf "basicConstraints=CA:TRUE\nkeyUsage=critical,nonRepudiation,keyCertSign,cRLSign\n")

@rem Specify key name used for file names
set ca_key_name=root-ca
 
@rem Create Certificate
set ca_csr_tmp_file=ca-csr-%RANDOM%.tmp
copy /Y NUL %ca_csr_tmp_file%
echo basicConstraints=CA:TRUE >> %ca_csr_tmp_file%
echo keyUsage=critical,nonRepudiation,keyCertSign,cRLSign >> %ca_csr_tmp_file%

openssl x509 -req -sha512 -days 7305 ^
    -key %ca_key_name%.key ^
    -in %ca_key_name%.csr ^
    -out %ca_key_name%.crt ^
    -extfile %ca_csr_tmp_file%

del /q %ca_csr_tmp_file%

Creating SSL/TLS Server Certificates

For a given server next steps includes to create the Private Key and Certificate Signing Request (CSR). The resulting Server Certificate will be signed by the Private CA. 

This step is performed for each Server Certificate that should be created.

Users can run the following commands from the shell and replace the value of the server_name environment variable with a name of their choice that is used when creating related files.

Creating the Private Key and Certificate Signing Request

Using ECDSA Encryption

# Specify key name used for file names
server_name=myhost

# Create Private Key
openssl ecparam -genkey -name secp384r1 -out ${server_name}.key

# Create Certificate Signing Request
openssl req -new -sha512 -nodes \
    -key ${server_name}.key \
    -out ${server_name}.csr \
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=${server_name}" 

@rem Specify key name used for file names
set server_name=myhost

@rem Create Private Key
openssl ecparam -genkey -name secp384r1 -out %server_name%.key

@rem Create Certificate Signing Request
openssl req -new -sha512 -nodes ^
    -key %server_name%.key ^
    -out %server_name%.csr ^
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=%server_name%"

Using RSA Encryption

# Specify key name used for file names
server_name=myhost

# Create Private Key and Certificate Signing Request
openssl req -new -newkey rsa:4096 -sha256 -nodes \
    -keyout ${server_name}.key \
    -out ${server_name}.csr \
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=${server_name}"

@rem Specify key name used for file names
set server_name=myhost

@rem Create Private Key and Certificate Signing Request
openssl req -new -newkey rsa:4096 -sha256 -nodes ^
    -keyout %server_name%.key ^
    -out %server_name%.csr ^
    -subj "/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=%server_name%"

Creating the Server Certificate

# Specify server for which the certificate should be created
server_name=myhost

# Create and sign Server Certificate
openssl x509 -req -sha512 -days 3652 \
    -in ${server_name}.csr \
    -CA root-ca.crt \
    -CAkey root-ca.key \
    -CAcreateserial \
    -out ${server_name}.crt \
    -extfile <(printf 'subjectAltName=DNS:%s\nkeyUsage=critical,keyEncipherment,digitalSignature\nextendedKeyUsage=serverAuth,clientAuth\n' "${server_name}")

@rem Specify key name used for file names
set server_name=myhost

@rem Create and sign Server Certificate
set server_crt_tmp_file=server-crt-%RANDOM%.tmp
copy /Y NUL %server_crt_tmp_file%
echo subjectAltName=DNS:%server_name% >> %server_crt_tmp_file%
echo keyUsage=critical,keyEncipherment,digitalSignature >> %server_crt_tmp_file%
echo extendedKeyUsage=serverAuth,clientAuth >> %server_crt_tmp_file%
 
openssl x509 -req -sha512 -days 3652 ^
    -in %server_name%.csr ^
    -CA root-ca.crt ^
    -CAkey root-ca.key ^
    -CAcreateserial ^
    -out %server_name%.crt ^
    -extfile %server_crt_tmp_file%

del /q %server_crt_tmp_file%

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_server_certificate.sh
  • certs
  • csr
  • private

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

Creating the Private Root CA Certificate

Download: create_root_ca.sh

The following files will be created when executing the script:

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

This step is performed just once. In case of renewal of the Root CA Certificate any Server Certificates will have to be renewed.

# Description
# create_root_ca.sh --key-name=<basename> --subject=<distinguished-name> --days=<number-of-days>

# Example for use with defaults
./create_root_ca.sh

# Example for use with basename
./create_root_ca.sh --key-name=ca-root

# Example applying specific distinguished name and lifetime
./create_root_ca.sh --subject="/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=JS7 CA" --days=7660

The shell script is optionally executed with the following arguments:

• --key-name
  • The basename of the key without extension. Default: root-ca
• --subject
  • The distinguished name that is used as the subject of the CA Certificate. Default: /C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=Root CA
• --days
  • The lifetime of the certificate is specified by the number of days. Default: 7305
  • Consider that Server Certificates have to be renewed if the Root CA Certificate expires.

Creating a Server Certificate

Download: create_server_certificate.sh

The following files will be created with <server> being a placeholder for the hostname for which a certificate should be created.

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

This step is performed for each Server Certificate that should be created.

# Description
# create_server_certificate.sh --dns=<hostname>[,<hostname>] --key-name=<basename> --subject=<distinguished-name> --days=<number-of-days>

# Example for use with DNS and lifetime
./create_server_certificate.sh --dns=centostest-primary --days=365

# Example for use with DNS, key name and lifetime
./create_server_certificate.sh --dns=centostest-primary,centostest-primary.sos --key-name=centostest-primary --days=4017

# Example for use with DNS, subject and lifetime
./create_server_certificate.sh --dns=centostest-primary,centostest-primary.sos --subject="/C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=centostest-primary.sos" --days=4017 

The shell script is executed with the following arguments:

• --dns (required)
  • The DNS hostname of the server that should be assigned the certificate. A server can be assigned more than one DNS hostname, for example the FQDN can extend the hostname. Only DNS hostnames that are added to the certificate can be used later on to establish secure HTTPS connections.
• --key-name
  • The basename of the key without extension. Default: root-ca
• --subject
  • The distinguished name that is used as the subject of the Server Certificate. Default: /C=DE/ST=Berlin/L=Berlin/O=SOS/OU=IT/CN=<dns>
  • The CN attribute must specify the server's hostname. By default the first hostname specified with the --dns option is used.
• --days
  • The lifetime of the certificate is specified by the number of days. Default: 3652

Links

• JS7 - How to add SSL TLS Certificates to Keystore and Truststore
• JS7 - How to create X.509 Signing Certificates