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Best Practices from Oracle Development's A‑Team

A dead simple certificate authority for testing purposes

Introduction

I don't know about you, but I know I'd rather spend an hour writing a script to automate something than 30 minutes figuring out how to use an existing but annoying/terrible tool. I do that not because I am a glutton for punishment, but because I know I'll have to use that terrible tool again in the future and I won't remember how to use it anyway.
So when I needed certificates for a test environment I checked out OpenSSL's built in CA tool, quickly decided against using it, and then wrote my own simpler tool.
Enjoy!

Update: There's a new version of this script available in a new post

Main Article

To use:

  1. make a directory to contain the script and the keys and certs it will generate
  2. copy/paste this code into a file in that directory. I called it make-cert, but use whatever name you like
  3. run it

The script takes one or more parameters that specify the CN of the cert you want it to generate. So

$ ./make-cert myserver.mydomain.com

will make a cert for myserver.mydomain.com. It will also take more than one CN on the command line, so

$ ./make-cert myserver.mydomain.com login.mydomain.com

will make a certificate for myserver.mydomain.com and another one for login.mydomain.com.

And here's the code

    #!/bin/bash     # a very, very simple cert authority     #     # Copyright 2011 Oracle     # christopher.johnson@oracle.com     #     # License agreement:     # ------------------     # This script is intended as a simple sample and/or for my own     # purposes. If you get any benefit from it then that's GREAT but     # there are NO warranties and NO support. If this script burns down     # your house, chases your dog away and spoils your milk please don't     # come crying to me.     baseAnswers() {         echo US         echo Massachusetts         echo Boston         echo Oracle         echo A-Team         echo $1         echo root@`hostname`     }     answers() {         baseAnswers $1         echo ''         echo ''     }     # better safe than sorry     umask 077     # these next two lines figure out where the script is on disk     SCRIPTPATH=`readlink -f $0`     SCRIPTDIR=`dirname $0`     # if you're running this from somewhere else...     if [  $SCRIPTDIR != "."    -a   $SCRIPTDIR != $PWD  ]; then         # then CD to that directory         cd $SCRIPTDIR         echo "Certificate and key files (.crt and .key) will be placed in $PWD"     fi     if [ ! -e ca.crt -o ! -e ca.key ]; then         echo "Creating cert authority key & certificate"         baseAnswers "My Cert Authority" | openssl req -newkey rsa:1024 -keyout ca.key -nodes -x509 -days 365 -out ca.crt 2> /dev/null     fi     if [ $# -eq 0 ] ; then         echo "This script creates one or more certificates."         echo "Provide one or more certificate CNs on the command line."         echo "Usage: `basename $0` <certcn> [certcn [...]]"         exit -1     fi     for certCN in $@ ; do         echo Certificate for CN \"$certCN\"         echo =============================================         KEY=$certCN.key         CRT=$certCN.crt         REQ=$certCN.req         ABORT=0         if [ -e $KEY ] ; then      echo " ERROR: Key file $KEY already exists"      ABORT=1         fi         if [ -e $REQ ] ; then      echo " ERROR: Request file $REQ already exists"      ABORT=1         fi         if [ -e $CRT ] ; then      echo " ERROR: Certificate file $CRT already exists"      ABORT=1         fi         if [ $ABORT -eq 1 ] ; then      echo ''      echo "If you wish to recreate a certificate for you must delete"      echo "any preexisting files for that CN before running this script."      echo ''      echo ''         else      answers $certCN | openssl req -newkey rsa:1024 -keyout $KEY -nodes -days 365 -out $REQ  2> /dev/null             # at this point we have a key file, but the cert is not signed by the CA      openssl x509 -req -in $REQ -out $CRT -CA ca.crt -CAkey ca.key -CAcreateserial -CAserial ca.serial 2> /dev/null      echo "Certificate created."      ls -l $KEY $REQ $CRT      echo 'Certificate information:'      openssl x509 -in $CRT -noout -issuer -subject -serial         fi     done     </certcn>

Note: an earlier version of this script was missing a $1 in the answers() function. The above script contains the correction.

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