File Coverage

blib/lib/Crypt/Curve25519.pm

Criterion	Covered	Total	%
statement	26	29	89.6
branch	4	6	66.6
condition			n/a
subroutine	8	9	88.8
pod	6	6	100.0
total	44	50	88.0

package Crypt::Curve25519;
#ABSTRACT: Generate shared secret using elliptic-curve Diffie-Hellman function

use strict;
use warnings;
use Carp qw( croak );

require Exporter;
our @ISA = qw(Exporter);
our $VERSION = '0.08';

our %EXPORT_TAGS = ( 'all' => [ qw(
    curve25519
    curve25519_secret_key
    curve25519_public_key
    curve25519_shared_secret
) ] );

our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );

our @EXPORT = qw(
    curve25519_secret_key
    curve25519_public_key
    curve25519_shared_secret
);

# Although curve25519_donna is also clamping the secret key this function
# has been provided for completeness and to ensure that secret keys generated
# here can be used in other implementations of the algorithm.
sub curve25519_secret_key {
    my $value = shift;
    croak 'Secret key requires 32 bytes' if length($value) != 32;
    vec($value, 0 , 8) &= 248;
    vec($value, 31, 8) &= 127;
    vec($value, 31, 8) |= 64;
    return $value;
}

require XSLoader;
XSLoader::load('Crypt::Curve25519', $Crypt::Curve25519::{VERSION} ?
    ${ $Crypt::Curve25519::{VERSION} } : ()
);

sub new {
    return bless(\(my $o = 1), ref $_[0] ? ref $_[0] : $_[0] );
}

sub secret_key {
    my ($self, $psk) = (shift, shift);

    my $masked = curve25519_secret_key( pack('H64', $psk) );

    return unpack('H64', $masked);
}

sub public_key {
    my ($self, $sk) = (shift, shift);
    my @args = pack('H64', $sk);
    if ( @_ ) {
        push @args, pack('H64', shift);
    }

    my $pk = unpack('H64', curve25519_public_key( @args ));

    return $pk;
}

sub shared_secret {
    my ($self, $sk, $pk) = @_;

    return unpack('H64', curve25519_shared_secret( pack('H64', $sk), pack('H64', $pk) ));
}

sub generate {
    my ($self, $sk, $bp) = @_;

    return unpack('H64', curve25519( pack('H64', $sk), pack('H64', $bp) ));
}

1;

__END__