shug94 has asked for the wisdom of the Perl Monks concerning the following question:

While trying to get Crypt::RSA to work I started getting some weird errors. I am trying to use a private key to sign some data. The error that I get is below (and I am not sure I understand it): 
[Thu Oct 22 15:01:36 2009] [error] [client 10.29.12.38] Can't call met
+hod "n" without a package or object reference at /usr/lib/perl5/site_
+perl/5.8.8/Crypt/RSA/
SS/PSS.pm line 41, <PRIVATE_KEY_FILE> line 15., referer: http://192.16
+8.15.2/cgi
-bin/RBS_MessageParameterCollectionGUI.pl

[download]

The code in question is shown below. Line 41 of PSS.pm is the 'my $k = octet_len ($key->n);' line: 
sub sign {
    my ($self, %params) = @_;
    my $key = $params{Key}; my $M = $params{Message} || $params{Plaint
+ext};
    return $self->error("No Key parameter", \$M, \%params) unless $key
+;
    return $self->error("No Message or Plaintext parameter", \$key, \%
+params) un
less $M;
    my $k = octet_len ($key->n);
    my $salt = makerandom_octet (Length => $self->{hlen});
    my $em = $self->encode ($M, $salt, $k-1);
    my $m = os2ip ($em);
    my $sig = $self->{primitives}->core_sign (Key => $key, Message => 
+$m);
    my $S = i2osp ($sig, $k);
    return ($S, $salt) if wantarray;
    return $S;
}

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The code in which I actually use the Crypt::RSA stuff is below: 
  my $rsa = new Crypt::RSA;
  my $signatureValue = $rsa->sign(
    Message    => $infoToSign,
    Key        => $privateKey);

[download]


If anyone has any idea as to why it is not working, or what might be going wrong, please let me know.

Cheers,
Shug

Replies are listed 'Best First'.
Re: Perl Crypt::RSA problems
by Anonymous Monk on Oct 22, 2009 at 05:20 UTC
    The code in which I actually use the Crypt::RSA stuff is below

    That code does not compile :)

[reply]
      OK, I'll bite. I am unsure if you are telling me that I need to include my entire chunk of code (cause clearly this is a fragment that won't compile on its own), or if there is some really obvious problem that I am just not seeing.

      I have pulled my code out of the context I am using it, and have written a little bit of practise code to try to get this to work. The practise code still has the same error. 

      #!/usr/bin/perl

use strict;
use Crypt::RSA;

print "RSA tester\n";

my $infoToSign = "blah";
my $privateKey = 5;

my $rsa = new Crypt::RSA;
my $signatureValue = $rsa->sign(
  Message    =>  $infoToSign,
  Key        =>  $privateKey,);

      [download]

      I still get the same problem. I realise that my key in this example is not legitimate, but it should still work, right?

      I might try generating a key using Crypt::RSA too.
[reply]
[d/l]

        Crypt::RSA says the key argument is a "Private key of the sender, a Crypt::RSA::Key::Private(3) or compatible object." On the other hand, you're passing an unblessed scalar, which has no methods, rather than an object with the API Crypt::RSA expects.

        You'll probably want to use something like
        $private = [doc://Crypt::RSA::Key::Private]->new(filename=>$private_key_file)
        to load the private key, and then pass that object along to sign().

[reply]
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