PEM files#

PEM (Privacy Enhanced Mail) is a standard for public key and certificate information, and an encoding standard used to transmit keys and certificates.

Trino supports PEM-encoded certificates. If you want to use other supported formats, see:

A single PEM-encoded file can contain either certificate or key pair information, or both in the same file. Certified keys can contain a chain of certificates from successive certificate authorities.

Follow the steps in this topic to inspect and validate PEM-encoded key and certificate files. See Inspect and validate keystore to validate JKS keystores.

Inspect PEM file#

The file name extensions shown on this page are examples only; there is no extension naming standard.

You may receive a single file that includes a private key and its certificate, or separate files. If you received separate files, concatenate them into one, typically in order from key to certificate. For example:

cat clustercoord.key clustercoord.cert > clustercoord.pem

Next, use the cat command to view this plain text file. For example:

cat clustercoord.pem | less

Make sure the PEM file shows at least one KEY and one CERTIFICATE section. A key section looks something like the following:


If your key section reports BEGIN ENCRYPTED PRIVATE KEY instead, this means the key is encrypted and you must use the password to open or inspect the key. You may have specified the password when requesting the key, or the password could be assigned by your site’s network managers.

If your key section reports BEGIN EC PRIVATE KEY or BEGIN DSA PRIVATE KEY, this designates a key using Elliptical Curve or DSA alternatives to RSA.

The certificate section looks like the following example:


The file can show a single certificate section, or more than one to express a chain of authorities, each certifying the previous.

Validate PEM key section#

This page presumes your system provides the openssl command from OpenSSL 1.1 or later.

Test an RSA private key’s validity with the following command:

openssl rsa -in clustercoord.pem -check -noout

Look for the following confirmation message:

RSA key ok


Consult openssl references for the appropriate versions of the verification commands for EC or DSA keys.

Validate PEM certificate section#

Analyze the certificate section of your PEM file with the following openssl command:

openssl x509 -in clustercoord.pem -text -noout

If your certificate was generated with a password, openssl prompts for it.

In the output of the openssl command, look for the following characteristics:

  • Modern browsers now enforce 398 days as the maximum validity period for a certificate. Look for Not Before and Not After dates in the Validity section of the output, and make sure the time span does not exceed 398 days.

  • Modern browsers and clients require the Subject Alternative Name (SAN) field. Make sure this shows the DNS name of your server, such as Certificates without SANs are not supported.

If your PEM certificate shows valid information for your cluster, proceed to configure the server, as described in Place the certificate file and Configure the coordinator.