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[DIR] Parent Directory       29-Jan-99 12:29      -  
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	Certificate questions
	Peter Antman
  To do something really useful with SSL (and thereby SSLtcl) one have
  to be able to handle certificate. This can sometimes be a little hard
  to learn, so here are a few word about what to do to create
  certificates.

  Autentication in SSL is partly done through a chain of signed
  certificates, where there somewhere in the end is a signer that you
  have good reason to trust. For Netscape-servers and clients, and even
  for apache-ssl, there are certain organizations that acts as
  Certificate Authorities. To have a website that people really know are
  your you can create a certificate and get an authority that everybody
  trust to guaranty that this certificate it really yours.

  In the lingua franca of SSL (and SSLtcl) we can hereby speak of two
  different kind of certificate. One is a CA certificate. That is, it is
  a certificate that you uses to verify other certificates against. The
  other is your own certificate, that is signed by someone else, in
  SSLtcl called cert.  You will also have a private key that accompanies
  the certificate (where your public key is).

  I don't know if any CA will sign certificates for use in SSLtcl based
  applications. But you can set up your own CA and creates your own
  certificates.

  In the demo directory there is includes a demoCA directory. In it I
  have placed a demo CA certificate and a signed certificate. The
  private keys are removed prom there password so that they can be used
  by anybody.

  But when you start using SSLtcl you probably wants to create your own
  certificates. The easiest way to do that is to use the script CA.sh in
  the demo directory. This is a slightly modified version of the CA.sh
  that comes with SSLeay.

  Create a directory where you want to store your certificates and copy
  CA.sh there or start ut with its full path. The following command will
  set a demoCA up for you and create a CA certificate, that is a self
  signed certificate.

       CH.sh -newca

  You will be asked some questions, just answer them the best you can.
  If you are running a website you should however pay attention to the
  question about your common name. Several clients demand that this is
  not your personal name but the domainname of the server.

  You are now a CA authority. Time to sign some certificates. You begin
  by creating a certificate request:

       CA.sh -newreq

  and answers the questions again. Now you send it to your CA which is
  you and you sign it:

       CA.sh -sign

  By now you have a CAfile, a cert and a key. The key to use is the key
  that was generated when you did your request, not your CA. As you saw
  you had to fill in a password or passphrase each time you generated a
  certificate. This is to protect the private key. Anybody thats gets
  hold of your plain private key can pretend his you. So it should be
  protected. But sometimes it is quite boring to have to type the
  passfrase every time you do something with a key.  Luckily the
  passfrase can be removed with the following command:

       ssleay rsa -in key.pwprotected -out key.plain

  You will find ssleay in the bin directory under ssl.

  I couple of questions might remain.

  How to I do to get a (Netscape) client to accept my new CA?

  Here is a small cgi-bin script that handle just that. You call it
  without argument from a webpage and the client will have it send to
  it, and reject or save it.

  The only thing you have to do is to convert your CA from pem to der
  encoded this way:

       x509 -inform pem -outform der < newca.pem > newca.der

       #!/bin/sh
       # ca-cert.sh
       #
       # (c) Peter Antman, 1997.
       #
       # cgi-bin-script to send a server ca file to netscape.
       # The script is called witout any argument, and the der-encoded certificate

       # is specified in the variable ''certfile''

       certfile=/home/www/certs/newca.der

       if [ -e $certfile ]; then
               echo ''Content-Type: application/x-x509-ca-cert''; echo

               cat $certfile
       else

               cat << END
       Content-Type: text/html

       <HTML>
       <HEAD><TITLE>Certificate not found!

       <BODY>
       <B>Sorry, I can't find the certificate I had planned to send back.  Please tr

       y again some other time.

       END
       fi

       exit 0

  How do I sign a client certificate for Netscape?

  This is also a good question for a server maintainer. Client
  authentication through certificates and SSL can be a good way of
  server data only to people you really know who they are.

  For Netscape there is a special FORM tag in html that can be used to
  get Netscape to generate a certificate request and send it (and also
  get it back with a special mime format). Here is a perl cgi-bin script
  that does just that. It is selfexplaining. Just one thing should be
  said. It actually does three separate things that actual could be done
  separately. It gets the request, it signs the request, and it sends it
  back.

  #!/usr/bin/perl -T
  # client
  #
  #(c) Peter Antman, 1997.
  #
  # This script handles at client-sertificate request from a form
  # containinggen the keygen name pair.
  #

  $ENV{PATH} = '/bin:/usr/bin:/usr/local/ssl/bin';

  $tempfil = ''/tmp/client-req'';
  $utfil = ''/tmp/client-cert.der'';

  $online = ''/tmp/online-cert'';

  # the ca program
  $passwd = oph84ov; # Password for your private key

  # Command for the ca-program to make a client certificate
  $ca = ''/usr/local/ssl/bin/ca -config /usr/local/ssl/lib/min.cnf -key oph84ov -spkac /tmp/client-req -out /tmp/client-cert.der'';

  #$arg =  ''-config /usr/local/ssl/lib/min.cnf -key oph84ov -spkac /tmp/client-req -out /tmp/client-cert.der'';

  #@args = (''-config /usr/local/ssl/lib/min.cnf'', ''-key oph84ov'', ''spkac /tmp/client-req'', ''-out /tmp/client-cert.der'');

  #Tar in postdata
  if ($ENV{''REQUEST_METHOD''} eq ''POST'') {
                  # Get the input
      read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});
                  # Split the name-value pairs
      @pairs = split(/&/, $buffer);
                  # Load the FORM variables
           foreach $pair (@pairs) {
               ($name, $value) = split(/=/, $pair);
               $value =~ tr/+/ /;
               $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack(''C'', hex($1))/eg;

               $FORM{$name} = $value;
           }

  # Print the request to a temporary file. Should we untaint the form-variables

  # with a REGEXP?

      open (h, ''>$tempfil'');

      print h ''C = $FORM{land}\n'';
      print h ''SP = $FORM{stad}\n'';
      print h ''O = $FORM{org}\n'';
      print h ''CN = $FORM{namn}\n'';
      print h ''Email = $FORM{epost}\n'';

  # This is kinky, the newlines have to be escaped with an ''\''

      $FORM{key} =~ s/\n/\\\n/g;

      print h ''SPKAC = $FORM{key}'';

      close h;

  # make the client certificate; untained with PATH set. In reality all the

  # elements in the form, including SPKAC ougt to be considered tainted. But

  # if there is not a bug in ca they are not harmfull, because they are not

  # passed trough the shell

      system $ca;

  # make an x509 online version to use for individual client certification with

  # apache-sll

      if (-e ''$online''){
           open (f, ''>>$online'');
       }
      else{
            open (f, ''>$online'');
        }

      print f ''/C=$FORM{land}/SP=$FORM{stad}/O=$FORM{org}/CN=$FORM{namn}/Email=$FORM{epost}:xxj31ZMTZzkVA\n'';

      close f;

  # Send the client certificate to the browser

      print ''Content-type: application/x-x509-user-cert\n\n'';

      open (h, ''$utfil'');
      while (<h>){
          print
          }

  }

  If you plan to get serious in your certification business you should
  have a look in ssleay.cof. This is the default format file for
  certificate generation and it contains sections that you will have to
  change directly in this file.  You should create your own format file
  and learn how to feed it to SSLeay when you handle certificates.