GnuPG::Tie::Encrypt from GNUPG, from the given example, would appear to be more what you might be looking for. It uses a tied file handle to interface with GnuPG, rather than requiring data to be written to a file to be encrypted.

Hope that helps.

Thank you so much, that does exactly what I want! I'm much farther along now, and sending messages works fine. However, on the receiving end when I try to decrypt the message I get: protocol error: expected DECRYPTION_OKAY got PLAINTEXT

I can't find where I've messed up, I tried to follow the example CPAN code as much as I could - but clearly I've done something wrong. I've marked the line near the very bottom where it appears to be erroring.

#!/usr/bin/env perl
use warnings;
use strict;
use Term::ReadKey; # For the noecho
use GnuPG::Tie::Encrypt;
use GnuPG::Tie::Decrypt;

# Global vars here
my $message_separator = "!"; # Separate messages on !, because gpg wil
+l put newlines into the message, but never uses '!' in ascii-armor
# End of global vars

client( $ARGV[0], $ARGV[1] ) if( @ARGV == 2 );
daemon( $ARGV[0] ) if( @ARGV == 1 );
usage() if( @ARGV != 1 && @ARGV != 2 );

sub usage
{
    print "Usage:\n";
    print "$0 <port_number> # For listening as a daemon\n";
    print "$0 <ip_address> <port_number> # For connecting to other ser
+vers\n";
}

sub client
{
    my $target = shift;
    my $port = shift;
    my $status = `nc -z $target $port` or die "Can't open data connect
+ion (port closed or host unreachable)";
    print "Who do I encrypt to: ";
    my $keyname = <STDIN>;
    chomp( $keyname );
    ReadMode('noecho');
    print "PGP Key passphrase (not echoed): ";
    my $passphrase = <STDIN>;
    chomp $passphrase;
    print "\n"; # The user's return key won't be echoed
    ReadMode(0); # Reset term status
    open (NET, "|-", "nc $target $port") or die "Can't open netcat: $!
+";
    while( 0 == 0 )
    {
        my $message = encrypt( $keyname, $passphrase );
        last if $message eq "exit";
        select(NET); # We select NET so $| will effect it
        $| = 1; # We can't buffer because of interactions with netcat.
        print $message . $message_separator; # Send it through the tub
+es!
    }
    close NET;
    select(STDOUT);
    print "Connection Terminated.\n";
}

sub encrypt
{
    select(STDOUT);
    my $keyname = shift;
    my $passphrase = shift;
    print "Message: ";
    my $message = <STDIN>;
    chomp( $message );
    return "exit" if( length($message) == 0 ); # Quit if blank message
    tie *ENCRYPT, 'GnuPG::Tie::Encrypt', recipient => $keyname, sign =
+> 1, passphrase => $passphrase, armor => 1;
    print ENCRYPT $message;
    local $/ = undef; # Don't stop reading from ENCRYPT at a newline l
+ike normal
    my $encrypted_message = <ENCRYPT>;
    close ENCRYPT;
    untie *ENCRYPT;
    return $encrypted_message;
}

sub daemon # Listen for incomming connections
{
    my $port = shift or die "Usage: $0 <port_number>";
    ReadMode('noecho');
    print "PGP Key passphrase (not echoed): ";
    my $passphrase = <STDIN>;
    chomp $passphrase;
    print "\n"; # The user's return key won't be echoed
    ReadMode(0); # Reset term status
    print( msg_time(), " Server started.\n");
    open (NET, "-|", "nc -k -l $port" ) or die "Can't open netcat!";
    local $/ = $message_separator; # Seperate off chosen symbol instea
+d of newline
    while( <NET> )
    {
        my $plaintext = decrypt($passphrase, $_);
        print( msg_time(), " ", $plaintext);
    }
    close NET; 
}

sub msg_time
{
    my( $hours, $minutes, $seconds ) = (localtime)[2,1,0];
    return "$hours:$minutes:$seconds";
}

sub decrypt
{
    my $passphrase = shift;
    my $message = shift;
    tie *DECRYPT, 'GnuPG::Tie::Decrypt', passphrase => $passphrase;
    print DECRYPT $message; # Here's where I error out
    my $plaintext_message = <DECRYPT>;
    close DECRYPT;
    untie *DECRYPT;
    return $plaintext_message;
}
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