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Concept

The first step to creating your Internal PKI is to create a Private Certificate Authority (CA) hierarchy that is a structure of entities used to issue digital certificates for services, applications, and devices.

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Workflow

A typical workflow for setting up a Private CA hierarchy consists of the following steps:

  1. Configuring an Infisical root CA with details like name, validity period, and path length — This step is optional if you wish to use an external root CA.
  2. Configuring and chaining intermediate CA(s) with details like name, validity period, path length, and imported certificate to your Root CA.
  3. Managing the CA lifecycle events such as CA succession.

Note that this workflow can be executed via the Infisical UI or manually such as via API. If manually executing the workflow, you may have to create a Certificate Signing Request (CSR) for the intermediate CA, create an intermediate certificate using the root CA private key and CSR, and import the intermediate certificate back to the intermediate CA as part of Step 2.

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Guide to Creating a CA Hierarchy

In the following steps, we explore how to create a simple Private CA hierarchy consisting of an (optional) root CA and an intermediate CA.

1

Creating a root CA

If you wish to use an external root CA, you can skip this step and head to step 2 to create an intermediate CA.

To create a root CA, head to your Project > Internal PKI > Certificate Authorities and press Create CA.

Here, set the CA Type to Root and fill out details for the root CA.

Here’s some guidance on each field:

  • Valid Until: The date until which the CA is valid in the date time string format specified here. For example, the following formats would be valid: YYYY, YYYY-MM, YYYY-MM-DD, YYYY-MM-DDTHH:mm:ss.sssZ.
  • Path Length: The maximum number of intermediate CAs that can be chained to this CA. A path of -1 implies no limit; a path of 0 implies no intermediate CAs can be chained.
  • Key Algorithm: The type of public key algorithm and size, in bits, of the key pair that the CA creates when it issues a certificate. Supported key algorithms are RSA 2048, RSA 4096, ECDSA P-256, and ECDSA P-384 with the default being RSA 2048.
  • Friendly Name: A friendly name for the CA; this is only for display and defaults to the subject of the CA if left empty.
  • Organization (O): The organization name.
  • Country (C): The country code.
  • State or Province Name: The state or province.
  • Locality Name: The city or locality.
  • Common Name: The name of the CA.
  • Require Template for Certificate Issuance: Whether or not certificates for this CA can only be issued through certificate templates (recommended).

The Organization, Country, State or Province Name, Locality Name, and Common Name make up the Distinguished Name (DN) or subject of the CA. At least one of these fields must be filled out.

2

Creating an intermediate CA

2.1. To create an intermediate CA, press Create CA again but this time specifying the CA Type to be Intermediate. Fill out the details for the intermediate CA.

2.2. Next, press the Install Certificate option on the intermediate CA from step 1.1.

2.3a. If you created a root CA in step 1, select Infisical CA for the Parent CA Type field.

Next, set the Parent CA to the root CA created in step 1 and configure the intended Valid Until and Path Length fields on the intermediate CA; feel free to use the prefilled values.

Here’s some guidance on each field:

  • Parent CA: The parent CA to which this intermediate CA will be chained. In this case, it should be the root CA created in step 1.
  • Valid Until: The date until which the CA is valid in the date time string format specified here. The date must be within the validity period of the parent CA.
  • Path Length: The maximum number of intermediate CAs that can be chained to this CA. The path length must be less than the path length of the parent CA.

Finally, press Install to chain the intermediate CA to the root CA; this creates a Certificate Signing Request (CSR) for the intermediate CA, creates an intermediate certificate using the root CA private key and CSR, and imports the signed certificate back to the intermediate CA.

Great! You’ve successfully created a Private CA hierarchy with a root CA and an intermediate CA. Now check out the Certificates page to learn more about how to issue X.509 certificates using the intermediate CA.

2.3b. If you have an external root CA, select External CA for the Parent CA Type field.

Next, use the provided intermediate CSR to generate a certificate from your external root CA and paste the PEM-encoded certificate back into the Certificate Body field; the PEM-encoded external root CA certificate should be pasted under the Certificate Chain field.

Finally, press Install to import the certificate and certificate chain as part of the installation step for the intermediate CA

Great! You’ve successfully created a Private CA hierarchy with an intermediate CA chained to an external root CA. Now check out the Certificates page to learn more about how to issue X.509 certificates using the intermediate CA.

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Guide to CA Renewal

In the following steps, we explore how to renew a CA certificate.

If renewing an intermediate CA chained to an Infisical CA, then Infisical will automate the process of generating a new certificate for the intermediate CA for you.

If renewing an intermediate CA chained to an external parent CA, you’ll be required to generate a new certificate from the external parent CA and manually import the certificate back to the intermediate CA.

Head to the CA Page of the CA you wish you renew and press Renew CA on the left side. Input a new Valid Until date to be used for the renewed CA certificate and press Renew to renew the CA.

The new Valid Until date must be within the validity period of the parent CA.

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