To convert the PEM-encoded public keys from this directory to TXT
records, run

    $ SELECTOR="8f00fb94ec6c37aacb48bd43e073f9b7"
    $ DOMAIN="fripost.org"
    $ printf "%s._domainkey.%s    IN TXT    (\n" "$SELECTOR" "$DOMAIN"; \
      { printf "v=DKIM1; k=rsa; t=s; s=email; p=";
        openssl pkey -pubin -in "./certs/dkim/$SELECTOR:$DOMAIN.pub" -outform DER | base64 -w0
      } | fold -w64 | sed 's/.*/    "&"/; $s/$/ )\n/'

Remove the "t=s" tag if subdomaining or third-party signature (hosted
domain) is required, cf. RFC 6376 sec. 3.6.1.