Introduction

JS7 - Deployment of Scheduling Objects makes use of Signing Certificates to digitally sign workflows and other objects. Use of certificates for signing is not related to use of certificates to secure connections using HTTPS.

• Certificates for the specific use of code signing must be used.
• Users choose which approach they want to follow:
  • Creating self-signed Certificates.
  • Creating Private CA-signed Certificates.
  • Buy Public CA-signed Certificates

Rollout of certificates to Controllers and Agents depends on the following choice:

• Self-signed Certificates have to be deployed from individual certificate files made available to Controllers and Agents.
  • There is no security gap in use of self-signed Certificates. When users store certificate files to Controllers and Agents then this proves that they trust the certificates.
• Private CA-signed Certificates are not deployed to Controllers and Agents. Instead, the CA Certificate is deployed that was used to sign individual certificates.
  • The approach includes that any signing certificate signed by the CA will be accepted for deployment of scheduling objects.
  • For better control which certificates are made available for deplyoment, users might decide to use a specific Intermediate CA.
• Public CA-signed Certificates are not created by users but are purchased from a trusted CA and therefore are not considered by the article.

Self-signed Certificates and Private CA Certificates are deployed to the <data>/config/private/trusted-x509-keys directory of Controller and Agent instances.

The article suggests the following steps for creation of both Self-signed Certificates and Private CA-signed Certificates:

• Create Private Key
• Create Certificate Signing Request (CSR)
• Create and sign Certificate

The article explains how to create Signing Certificates for use with JS7. Users who operate their Private Certificate Authority might find different approaches and different responsibilities for the indicated steps. There's more than one way how to do it.

Examples in the article make use of OpenSSL 1.1.1k  FIPS 25 Mar 2021 and JS7 Release 2.7.2. OpenSSL ships with Linux & other Unix OS and is available for Windows. The examples are focused on Unix.

Creating the Private Key and Certificate Signing Request

The steps to create a Private Key and Certificate Signing Request are the same for use of self-signed Certificates and Private CA-signed Certificates. 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 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
key_name=signing

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

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

Explanation:

• Private Key
  • Choice of algorithm such as secp256k1, secp384r1 depends on support by the Java version used with JS7.
• Certificare Signing Request
  • The hash algorithm such as -sha256, -sha512 can be freely chosen.
  • The -subj option specifies the Distinguished Name used for the subject of the CSR and resulting Certificate.
    • The Distinguished Name is a unique identifier frequently using the hierarchy of Country C, State ST, Location L, Organization O, Organizational Unit OU and Common Name CN.
    • For self-signed Certificates the subject and issuer properties of the CSR/Certificate are the same. The minimum requirement is to specify the Common Name CN=<name> where <name> can freely be chosen.
    • For Private CA-signed Certificates the subject property holds the Certificate's Distinguished Name and the issuer property holds the Private CA Certificate's Distinguished Name using different values.
• The following files will be created with this step:
  • The <key_name>.key file will hold the Private Key.
  • The <key_name>.csr file will hold the Certificate Signing Request.

Using RSA Encryption

# Specify key name used for file names
key_name=signing

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

Explanation:

• In the example the Private Key is created using the specified key size 4096.
• Choice of algorithm such as secp256k1, secp384r1 depends on support by the Java version used with JS7.
• For use of the -subj option see Using ECDSA Encryption.
• The following files will be created with this step:
  • The <key_name>.key file will hold the Private Key.
  • The <key_name>.csr file will hold the Certificate Signing Request.

Creating Certificates

Users have the option to create self-signed Certificates or Private CA-signed Certificates.

Creating self-signed Certificates

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

# Specify key name used for file names
key_name=signing

# Create Certificate
openssl x509 -req -sha512 -days 3652 \
    -signkey "${key_name}".key \
    -in "${key_name}".csr \
    -out "${key_name}".crt \
    -extfile <(printf "keyUsage=critical,nonRepudiation,digitalSignature\nextendedKeyUsage=critical,codeSigning\n")

Explanation:

• The SHA option such as -sha256, -sha384, -sha512 should preferably match the value of the option used when creating the Certificate Signing Request.
• The -days argument optionally specifies the validity period of the resulting Certificate.
• The -signkey option specifies the location of the Private Key file created from the previous step.
• The -in option specifies the location of the Certificate Signing Request file created from the previous step.
• The -out option specifies the location of the resulting Certificate file.
• The -extfile option specifies a number of extensions recommended for use with Signing Certificates. 
• The following files will be created with this step:
  • The <key_name>.crt file will hold the self-signed Certificate.

Self-signed Certificates must be copied to the <data>/config/private/trusted-x509-keys directory of Controller and Agent instances.

Creating Private CA-signed Certificates

For Private CA-signed Certificates a Certificate Authority (CA) is required owning a CA Private Key and CA Certificate. The CA Private Key and CA Certificate will be used to sign certificates on behalf of users.

• Setup of the Certificate Authority is performed once.
• Signing is performed for each certificate on behalf of users.

Creating the Private Certificate Authority (CA)

The steps to create the CA Private Key and CA Certificate are similar to Creating the Private Key and Certificate Signing Request for self-signed Certificates.

Creating the CA Private Key and Certificate Signing Request

Steps include to create the signing-ca.key CA Private Key file and signing-ca.csr CA Certificate Signing Request file both 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=signing-ca

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

# Create Certificate Signing Request (CSR)
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}"

Explanation:

• Explanations are the same as from Creating Private Key and Certificate Signing Request for self-signed Certificates.
• Users can choose Using ECDSA Encryption or Using RSA Encryption.

Creating the CA Certificate

Steps include to create the signing-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=signing-ca

# Create Certificate
openssl x509 -req -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")

Explanation:

• Explanations are similar to Creating self-signed Certificates with a few exceptions.
  • The -days option specifying the validity period of the CA Certificate should be longer than the validity period of individual certificates.
  • The -extfile option specifies the Basic Constraint CA:TRUE which is required for a CA Certificate. Key Usage is limited to signing certificates.
• The following files will be created with this step:
  • The signing-ca.crt file will hold the CA Certificate.

The CA Certificate must be copied to the <data>/config/private/trusted-x509-keys directory of Controller and Agent instances.

Creating Signing Certificates

Creating the Signing Private Key and Certificate Signing Request

Steps include to create the signing.key Private Key file and signing.csr Certificate Signing Request file both in PEM format.

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

# Specify key name used for file names
key_name=signing

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

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

Explanation:

• Explanations are the same as with Creating Private Key and Certificate Signing Request for self-signed Certificates.
• Users can choose Using ECDSA Encryption or Using RSA Encryption.

Creating the Signing Certificate

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

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

# Specify key name used for file names
key_name=signing

# Create Certificate
openssl x509 -req -sha512 -days 3652 \
    -in "${key_name}".csr \
    -CA signing-ca.crt \
    -CAkey signing-ca.key \
    -CAcreateserial \
    -out "${key_name}".crt \
    -extfile <(printf '\nkeyUsage=critical,nonRepudiation,digitalSignature\nextendedKeyUsage=critical,codeSigning\n')

Explanation:

• Explanations are similar to Creating self-signed Certificates with a few exceptions:
  • The -days option specifying the validity period of the Signing Certificate should indicate a shorter period than the validity period of the CA Certificate.
  • The -in option specifies the location of the Certificate Signing Request.
  • The -CA option specifies the location of the CA Certificate file.
  • The -CAkey option specifies the location of the CA Private Key file.
  • The -extfile option specifies the Key Usage being limited to code signing.
• The following files will be created with this step:
  • The signing.crt file will hold the Signing Certificate..

The Signing Certificate file does not require to be deployed to Controller and Agent instances. Instead, the CA Certificate file is deployed to Controller and Agent instances.