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pcert

PkgGoDev

pcert aims to ease the creation of x509 certificates and keys.

The simple case is as easy as this:

pcert create

This would write the certificate and key to standard output.

You can write the certificate and key to a file by specifying either only the certificate path or both pathes:

pcert create tls.crt
pcert create tls.crt tls.key

The two invocations above are equivalent. When omitting the path for the key file the key file is written into the same directory as the certificate to a file with the same name but ending in .key.

Quick start

Self-signed server certificate

pcert create tls.crt --server --dns myserver.example.com

Signed certificates (CA)

To create your own CA and sign certificates with it you first create a CA (self-signed) certificate:

pcert create ca.crt --ca --name "My CA"

Then you can create and sign certificates with it:

# server
pcert create server.crt --server --dns foo.example.com --dns bar.example.com

# client
pcert create client.crt --client --name "my client"

Auto completion

Shell completion can be enabled for bash, zsh, fish and ps (Power Shell). It supports not only completion for the commands, but also for certain flags (e.g. --key-usage, --ext-key-usage, --sign-alg) where the valid options are hard to remember.

source <( pcert completion bash )

Expiry

The validity period of certificates default to one year starting from the creation time. The period can be changed by using the options --not-before, --not-after and --expiry. The options --not-before and --not-after allow to set the NotBefore and NotAfter value to a certain date (RFC3339):

pcert create --not-before 2020-01-01T12:00:00+01:00 --not-after 2020-06-01T12:00:00+01:00

The option --expiry allows to specify a duration instead of explicit dates:

# certificate valid until 90days from now
pcert create --expiry 90d

# certificate valid until 3 years (3 * 365 days)
pcert create --expiry 3y

Environment variables

All command line flags can also be set using environment variables. For this you have to make the flag name upper-case, repalce - with _ and prefix it with PCERT_.

For example:

  • --sign-cert=ca.crt => PCERT_SIGN_CERT=ca.crt
  • --subject-country CH => PCERT_SUBJECT_COUNTRY=CH

Command line flags take precedence over environment variables. Be aware that for flags you can specify multiple times (e.g. --dns) the values from the environment and form the command line flags are combined.

Examples

Local CA

Here is an example of how you could use pcert to create a local CA:

Create CA certificate and key in ~/pki:

mkdir ~/pki
pcert create ~/pki/ca.crt --ca

If you like you can add the newly created certificate ~/pki/ca.crt to you system trust store.

Now we set PCERT_SIGN_CERT that all newly created certificates are signed with our CA in ~/pki. This environment variable could be added to .bashrc for example:

export PCERT_SIGN_CERT=~/pki/ca.crt
export PCERT_SIGN_KEY=~/pki/ca.key

From now on if we use pcert create it creates certificates which are signed by our local CA. If you still would create a self-signed certificate you would have to set --sign-cert="".

Intermediate CA

This example shows how to make an intermediate CA certificate:

Create root CA certificate and key:

pcert create root.crt --ca

Create intermediate CA certificate:

pcert create intermediate.crt --ca --sign-cert root.crt

Create server certificate from the intermediate CA:

pcert create server.crt --sign-cert indtermediate.crt --dns myserver.example.com