Re: Convert::ASN1 example needed

[Chris R. <chr...@me...>]

Graham Barr <gb...@po...> wrote:

> On Mon, Jul 31, 2000 at 03:57:33PM +0100, Chris Ridd wrote:
>> I just had a quick go, and am having problems.
>
> Like ?

Erm, I think I just had the ASN.1 wrong :-)

Well, here's an attempt at decoding the timestamps from a cert:

-----
#!/usr/bin/perl -w

use strict;
use Carp;
use Convert::ASN1;

my $cert;
{
    local $/ = undef;
    open CERT, "mycert.der" or die;
    $cert = <CERT>;
    close CERT;
}

my $asn = Convert::ASN1->new;

# Can't get this to work. Want to stop Convert::ASN1 from changing the
# UTCTime values...
#my %opts = (
#	    timezone => [0,0]
#	   );
#$asn->configure(decode => \%opts);

# Ignore pretty much everything
$asn->prepare(q<
	      SEQUENCE {
		  SEQUENCE {
		      version      [0] IMPLICIT INTEGER OPTIONAL,
		      serialNumber ANY,
		      signature    ANY,
		      issuer       ANY,
		      SEQUENCE {
			  notBefore UTCTime,
			  notAfter UTCTime
		      }
		      subject      ANY,
		      spkinfo      ANY,
		      issueruid    [1] IMPLICIT ANY OPTIONAL,
		      subjectuid   [2] IMPLICIT ANY OPTIONAL,
		      extensions   [3] ANY OPTIONAL
		  }
		  alg ANY OPTIONAL,
		  sig BIT STRING
	      }>) or die;

my $out = $asn->decode($cert) or die;

print "NotBefore: " . $out->{notBefore} . "\n";
print "NotAfter:  " . $out->{notAfter} . "\n";

----

I couldn't persuade Convert::ASN1 from messing with the time strings. 
Replacing 'UTCTime' above with '[UNIVERSAL 23] IMPLICIT STRING' will get 
the correct unadulterated times back...

Cheers,

Chris