Crypt::Ctr::FullWidth - Like L<Crypt::Ctr> but works at the blocksize, not word size.

	use Crypt::Ctr::FullWidth;

	my $cipher = new Crypt::Ctr::FullWidth $key, 'Crypt::Rijndael';

	my $ciphertext = $cipher->encrypt($plaintext);
	my $plaintext = $cipher->decrypt($ciphertext);

	my $cipher2 = new Crypt::Ctr::FullWidth $key, 'Digest::MD5';

	$ciphertext = $cipher->encrypt($plaintext);
	$plaintext = $cipher->decrypt($ciphertext);

package Crypt::Ctr::FullWidth;
use base qw(Crypt::CFB);

use strict;
use warnings;

sub _statef;

sub new {
	my ($proto, $key, $algo) = @_;
	my $class = ref($proto) || $proto;
	my $self = new Crypt::CFB ($key, $algo);
	$self->{statef} = \&_statef;
	bless ($self, $class);
}

	
sub _statef {
	my $self = shift;

	my @ints = reverse unpack "n*", $self->{register};

	use integer; # unsigned
	foreach my $int ( @ints ) {
		$int++;
		last unless $int & ( 1 << 16 ); # we can stop if the integer didn't overflow
	}

	$self->{register} = pack("n*", reverse @ints);
}

sub bencrypt {
	my ($self, $block, $d) = @_;
	my $xor = &{$self->{cf}}();
	my $out = $block ^ substr($xor, 0, length($block) );
	if ($d) {
		&{$self->{statef}}($self,$block);
	} else {
		&{$self->{statef}}($self,$out);
	}
	return $out;
}

sub _encrypt {
	my ($self, $string, $d) = @_;
	my ($out, $i, $l);
	my $blocksize = $self->{registerlength};
	join '', map { $self->bencrypt($_, $d) } unpack("(a$blocksize)*", $string);
}

# UGH! gotta duplicate these tow because they call _encrypt as a function, not a method
sub encrypt {
	my ($self, $string) = @_;
	return $self->_encrypt($string, 0);
}

sub decrypt {
	my ($self, $string) = @_;
	return $self->_encrypt($string, 1);
}

sub set_nonce {
	my ( $self, $nonce ) = @_;
	$self->{register} = $nonce;
}

1;
__END__