File Coverage

blib/lib/Crypt/Present.pm

Criterion	Covered	Total	%
statement	65	73	89.0
branch	7	12	58.3
condition			n/a
subroutine	7	12	58.3
pod	4	8	50.0
total	83	105	79.0

package Crypt::Present;

use strict;
use warnings;

our @ISA = qw();

our $VERSION = '0.02';


use Carp;

my @SBoxBits;
my @SBoxByte;
my @SBoxByteRev;
my @V5Bits;
my @pLVec;
BEGIN {
  my @SBox = ( 0xC, 0x5, 0x6, 0xB, 0x9, 0x0, 0xA, 0xD, 0x3, 0xE, 0xF, 0x8, 0x4, 0x7, 0x1, 0x2 );
  @SBoxBits = map unpack('B4',chr($_<<4)), @SBox;
  @SBoxByte = map { my $h = ( $_ & 0xF0 ) >> 4;
		    my $l = ( $_ & 0x0F );
                    chr( ( $SBox[$h] << 4 ) | $SBox[$l] );
		  } ( 0 .. 255 );
  foreach ( 0 .. 255 ) { $SBoxByteRev[ord($SBoxByte[$_])] = chr $_; }

  push @V5Bits, unpack('B5',chr($_<<3)) foreach (0..31);

  my @pLayer; # ( 0, 16, 32, 48, ... );
  for ( my $i = 0; $i < 16; $i++ ) {
    $pLayer[$i*4+0] = $i;
    $pLayer[$i*4+1] = $i + 16;
    $pLayer[$i*4+2] = $i + 32;
    $pLayer[$i*4+3] = $i + 48;
  }
  for my $i ( 0 .. 63 ) {
    my $p  =  $pLayer[$i];
    my $iv =  int($i/8)*8+(7-($i%8));
    my $pv =  int($p/8)*8+(7-($p%8));
    $pLVec[$iv] = $pv;
  }
}


sub usage
{
  my ($package, $filename, $line, $subr) = caller(1);
  $Carp::CarpLevel = 2;
  croak "Usage: $subr(@_)";
}


sub blocksize   {   8; }
sub keysize     { my $k = $_[0]->{KEY}; return defined($k) ? length($k) : [ 80, 128 ]; }
sub min_keysize {  80; }
sub max_keysize { 128; }

my $genRoundKeys = sub ($) {
  my $self = shift;

  my $key = $self->{KEY};

  my @roundKeys;

  if ( length($key) == 10 ) {

    push @roundKeys, substr( $key, 0, 8 );
    $key = unpack('B*',$key);
    for ( my $i = 1; $i <= 31; $i++ ) {
      $key = $SBoxBits[ord(pack('B8','0000'.substr( $key, 61, 4 )))] . substr( $key, 65, 15 ) . substr( $key, 0, 61 );
      $key = substr( $key, 0, 60 ) . $V5Bits[(ord(pack("B5",substr( $key, 60, 5 )))>>3)^$i] . substr( $key, 65, 15 );
      push @roundKeys, substr( pack('B*',$key), 0, 8 );
    }

  } elsif ( length($key) == 16 ) {

    push @roundKeys, substr( $key, 0, 8 );
    $key = unpack('B*',$key);
    for ( my $i = 1; $i <= 31; $i++ ) {
      $key = $SBoxBits[ord(pack('B8','0000'.substr( $key, 61, 4 )))] . $SBoxBits[ord(pack('B8','0000'.substr( $key, 65, 4 )))] . substr( $key, 69, 59 ) . substr( $key, 0, 61 );
      $key = substr( $key, 0, 61 ) . $V5Bits[(ord(pack("B5",substr( $key, 61, 5 )))>>3)^$i] . substr( $key, 66, 62 );
      push @roundKeys, substr( pack('B*',$key), 0, 8 );
    }

  } else {
    die 'key size must be 80 or 128 but not '.(8 * length $key);
  }

  return $self->{ROUND_KEYS} = \@roundKeys;
};


sub new ($;$) {
  usage("new Present key") unless @_ == 2;
  my $class = shift;
  my $key   = shift;

  my $self = bless { KEY => $key }, $class;
  &$genRoundKeys($self);
  return $self;
}


my $null64 = "\x00" x 8; # 64 bit null value


sub encrypt ($$) {
  usage("encrypt data[8 bytes]") unless @_ == 2;
  my $self = shift;
  my $data = shift; # plaintext

  my $roundKeys = $self->{ROUND_KEYS}; # $roundKeys = &$genRoundKeys($self) if !defined $roundKeys;

  for ( my $i = 0; $i <= 30; $i++ ) {
    $data = $data ^ $roundKeys->[$i];
    $data = join '', map { $SBoxByte[ord($_)]; } split //, $data;
    { # permutate
      my $c = $null64;
      #foreach ( 0 .. 63 ) { vec( $c, $pLVec[$_], 1 ) = 1 if vec( $b, $_, 1 ); }
      for ( my $j = 64; $j--; ) { vec( $c, $pLVec[$j], 1 ) = 1 if vec( $data, $j, 1 ); }
      $data = $c;
    }
  }
  $data = $data ^ $roundKeys->[31];

  return $data;
}


sub decrypt ($$) {
  usage("decrypt data[8 bytes]") unless @_ == 2;
  my $self = shift;
  my $data = shift; # ciphertext

  my $roundKeys = $self->{ROUND_KEYS}; # $roundKeys = &$genRoundKeys($self) if !defined $roundKeys;

  $data = $data ^ $roundKeys->[31];
  for ( my $i = 30; $i >= 0; $i-- ) {
    { # permutate
      my $c = $null64;
      #foreach ( 0 .. 63 ) { vec( $c, $_, 1 ) = 1 if vec( $data, $pLVec[$_], 1 ); }
      for ( my $j = 64; $j--; ) { vec( $c, $j, 1 ) = 1 if vec( $data, $pLVec[$j], 1 ); }
      $data = $c;
    }
    $data = join '', map { $SBoxByteRev[ord($_)]; } split //, $data;
    $data = $data ^ $roundKeys->[$i];
  }

  return $data;
}


1;

__END__