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Generating certificates

You can generate certificates to use with TLS using a third-party tool such as OpenSSL or Keytool.

This guide explains how to use OpenSSL to generate certificates when the Common Name (CN) is either the public DNS or an IP address. Before you begin, ensure OpenSSL is installed.

Public DNS as CN​

Follow these steps to use a public DNS as CN.

Generating a CA certificate​

  1. Generate a key file called tessera_ca.key:

    openssl genrsa -out tessera_ca.key 2048

  2. Generate a certificate authority (CA) certificate called tessera_ca.pem that uses tessera_ca.key:

    openssl req -x509 -new -nodes -key tessera_ca.key -sha256 -days 1024 -out tessera_ca.pem

Generating a new certificate for a node​

We recommend each node has its own certificate. To generate the certificate:

  1. Generate a key file called tessera_cer.key:

    openssl genrsa -out tessera_cer.key 2048

  2. Generate a certificate signing request (CSR) called tessera_cer.csr:

    openssl req -new -key tessera_cer.key -out tessera_cer.csr

  3. Answer each prompt for information to be added to the certificate request. Ensure the value you specify for CN matches the host public DNS so the requests from the server are accepted. The name is also specified in the configuration file for the nodeurl and clienturl options.

info

If running on localhost, make sure localhost is specified in CN.

  1. Generate a certificate called tessera_cer.pem signed by the CA certificate:

    openssl x509 -req -in tessera_cer.csr -CA tessera_ca.pem -CAkey tessera_ca.key -CAcreateserial -out tessera_cer.pem -days 500 -sha256

IP address as CN​

Follow these steps to use a public IP address as CN.

Updating the openssl.cnf file​

  1. Find the openssl.cnf file, and create a copy of it.

  2. In your copy of the openssl.cnf file, find the [req] section, and add:

    req_extensions = v3_req

    [ v3_req ]
    basicConstraints = CA:FALSE
    keyUsage = nonRepudiation, digitalSignature, keyEncipherment
    subjectAltName = @alt_names

    [alt_names]
    DNS.1 = <DNS-PUBLIC-RECORD>
    DNS.2 = <DNS-PRIVATE-RECORD>
    IP.1 = <PUBLIC-IP-ADDRESS>
    IP.2 = <PRIVATE-IP-ADDRESS>

  3. For each DNS you want to use as an alternate name, specify a DNS.n entry.

  4. For each IP address you want as an alternate IP address, specify an IP.n entry.

    note

    When running on localhost, include 127.0.0.1 as a listed IP address.

Generating a new CSR for a node​

  1. Run the following command. Substitute your values for all variables.

    openssl req -new -key tessera_cer.key -out tessera_cer.csr -config <PATH-TO>/openssl.cnf

  2. Test whether the certificate was generated with the expected subject alternative names:

openssl req -text -noout -in tessera_cer.csr

Generating a new certificate​

  1. Run the following command. Substitute your values for all variables.

    openssl x509 -req -in tessera_cer.csr -CA tessera_ca.pem -CAkey tessera_ca.key -CAcreateserial -out tessera_cer.pem -days 500 -sha256 -extfile <PATH-TO>/openssl.cnf -extensions v3_req

  2. Test whether the generated certificate contains the subject alternative names:

openssl x509 -in tessera_cer.pem -text -noout