/ 
Crypt-NaCl-Sodium-0.03
River stage one • 1 direct dependent • 2 total dependents
/ Crypt::NaCl::Sodium::scalarmult

NAME

Crypt::NaCl::Sodium::scalarmult - Diffie-Hellman (Curve25519)

VERSION

version 0.03

SYNOPSIS

use Crypt::NaCl::Sodium qw( :utils );

my $crypto_scalarmult = Crypt::NaCl::Sodium->scalarmult();

my ($a_skey, $a_pkey, $a_shared_key, $a_key
    $b_skey, $b_pkey, $b_shared_key, $b_key);

## Alice
########

# Alice generates secret key
$a_skey = $crypto_scalarmult->keygen();

# and computes the public key
$a_pkey = $crypto_scalarmult->base( $a_skey );

# ... and shares it with Bob
send_to( Bob => { public_key => $a_pkey } );

## Bob
########

# Bob generates his secret key
$b_skey = $crypto_scalarmult->keygen();

# and computes the public key
$b_pkey = $crypto_scalarmult->base( $b_skey );

# ... and shares his public key with Alice
send_to( Alice => { public_key => $b_pkey } );

# Bob receives the public key from Alice
$a_key = receive_for( Bob => 'public_key' );

# Bob can now calculate the shared secret key
$b_shared_key = $crypto_scalarmult->shared_secret( $b_skey, $a_key );

## Alice
########

# Alice receives the public key from Bob
$b_key = receive_for( Alice => 'public_key' );

# and can now also calculate the shared secret key
$a_shared_key = $crypto_scalarmult->shared_secret( $a_skey, $b_key );

# shared keys calculated by Alice and Bob are equal
$a_shared_key eq $b_shared_key or die;

# NOTE: send_to() and receive_for() and user functions providing transport of
# messages

DESCRIPTION

crypto_scalarmult provides Curve25519, a state-of-the-art Diffie-Hellman function suitable for a wide variety of applications, eg. authenticate and encrypt messages between both parties.

METHODS

keygen

my $secret_key = $crypto_scalarmult->keygen();

Helper method to generate a random secret key to be used by $crypto_scalarmult.

The length of the $secret_key equals "SCALARBYTES".

The same secret key can be used with multiple other users, without the need of generating a distinct set of keys.

NOTE: keep the secret key confidential.

Returns Data::BytesLocker objects.

base

my $public_key = $crypto_scalarmult->base( $secret_key );

Computes the public key for corresponding secret key.

The length of the $public_key equals "BYTES".

Returns Data::BytesLocker objects.

shared_secret

my $shared_key = $crypto_scalarmult->shared_secret( $sender_secret_key, $recipient_public_key );

Given a user's secret key $sender_secret_key and another user's public key $recipient_public_key, computes a secret shared by the two users and returns it. This secret can then be used to authenticate and encrypt messages between the two users.

The length of the $shared_key equals "BYTES".

Returns Data::BytesLocker objects.

CONSTANTS

BYTES and SCALARBYTES are provided for consistency, but it is safe to assume that BYTES == SCALARBYTES.

BYTES

my $pkey_length = $crypto_scalarmult->BYTES;

Returns the length of public key (and shared secret).

SCALARBYTES

my $skey_length = $crypto_scalarmult->SECRETKEYBYTES;

Returns the length of secret key.

ALGORITHM DETAILS

crypto_scalarmult uses Curve25519.

SEE ALSO

AUTHOR

Alex J. G. Burzyński <ajgb@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2015 by Alex J. G. Burzyński <ajgb@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.