Crypt::PK::DH(3)

NAME
Crypt::PK::DH - Public key cryptography based on Diffie-Hellman

SYNOPSIS
 ### OO interface

 #Shared secret
 my $priv = Crypt::PK::DH->new('Alice_priv_dh1.key');
 my $pub = Crypt::PK::DH->new('Bob_pub_dh1.key');
 my $shared_secret = $priv->shared_secret($pub);

 #Key generation
 my $pk = Crypt::PK::DH->new();
 $pk->generate_key(128);
 my $private = $pk->export_key('private');
 my $public = $pk->export_key('public');

 or

 my $pk = Crypt::PK::DH->new();
 $pk->generate_key('ike2048');
 my $private = $pk->export_key('private');
 my $public = $pk->export_key('public');

 or

 my $pk = Crypt::PK::DH->new();
 $pk->generate_key({ p => $p, g => $g });
 my $private = $pk->export_key('private');
 my $public = $pk->export_key('public');

 ### Functional interface

 #Shared secret
 my $shared_secret = dh_shared_secret('Alice_priv_dh1.key', 'Bob_pub_dh1.key');

METHODS

  new
  my $pk = Crypt::PK::DH->new();
  #or
  my $pk = Crypt::PK::DH->new($priv_or_pub_key_filename);
  #or
  my $pk = Crypt::PK::DH->new(\$buffer_containing_priv_or_pub_key);

  generate_key
Uses Yarrow-based cryptographically strong random number generator seeded with random data taken from "/dev/random" (UNIX) or "CryptGenRandom" (Win32).

 $pk->generate_key($groupsize);
 ### $groupsize (in bytes) corresponds to DH parameters (p, g) predefined by libtomcrypt
 # 96   =>  DH-768
 # 128  =>  DH-1024
 # 192  =>  DH-1536
 # 256  =>  DH-2048
 # 384  =>  DH-3072
 # 512  =>  DH-4096
 # 768  =>  DH-6144
 # 1024 =>  DH-8192

The following variants are available since CryptX-0.032

 $pk->generate_key($groupname)
 ### $groupname corresponds to values defined in RFC7296 and RFC3526
 # 'ike768'  =>  768-bit MODP (Group 1)
 # 'ike1024' => 1024-bit MODP (Group 2)
 # 'ike1536' => 1536-bit MODP (Group 5)
 # 'ike2048' => 2048-bit MODP (Group 14)
 # 'ike3072' => 3072-bit MODP (Group 15)
 # 'ike4096' => 4096-bit MODP (Group 16)
 # 'ike6144' => 6144-bit MODP (Group 17)
 # 'ike8192' => 8192-bit MODP (Group 18)

 $pk->generate_key($param_hash)
 # $param_hash is { g => $g, p => $p }
 # where $g is the generator (base) in a hex string and $p is the prime in a hex string

 $pk->generate_key(\$dh_param)
 # $dh_param is the content of DER or PEM file with DH parameters
 # e.g. openssl dhparam 2048

  import_key
Loads private or public key (exported by "export_key").

  $pk->import_key($filename);
  #or
  $pk->import_key(\$buffer_containing_key);

  import_key_raw
Since: CryptX-0.032

  $pk->import_key_raw($raw_bytes, $type, $params)
  ### $raw_bytes is a binary string containing the key
  ### $type is either 'private' or 'public'
  ### $param is either a name ('ike2038') or hash containing the p,g values { g=>$g, p=>$p }
  ### in hex strings

  export_key
BEWARE: DH key format change - since v0.049 it is compatible with libtomcrypt 1.18.

 my $private = $pk->export_key('private');
 #or
 my $public = $pk->export_key('public');

  export_key_raw
Since: CryptX-0.032

 $raw_bytes = $dh->export_key_raw('public')
 #or
 $raw_bytes = $dh->export_key_raw('private')

  shared_secret
 # Alice having her priv key $pk and Bob's public key $pkb
 my $pk  = Crypt::PK::DH->new($priv_key_filename);
 my $pkb = Crypt::PK::DH->new($pub_key_filename);
 my $shared_secret = $pk->shared_secret($pkb);

 # Bob having his priv key $pk and Alice's public key $pka
 my $pk = Crypt::PK::DH->new($priv_key_filename);
 my $pka = Crypt::PK::DH->new($pub_key_filename);
 my $shared_secret = $pk->shared_secret($pka);  # same value as computed by Alice

  is_private
 my $rv = $pk->is_private;
 # 1 .. private key loaded
 # 0 .. public key loaded
 # undef .. no key loaded

  size
 my $size = $pk->size;
 # returns key size in bytes or undef if no key loaded

  key2hash
 my $hash = $pk->key2hash;

 # returns hash like this (or undef if no key loaded):
 {
   type => 0,   # integer: 1 .. private, 0 .. public
   size => 256, # integer: key size in bytes
   x => "FBC1062F73B9A17BB8473A2F5A074911FA7F20D28FB...", #private key
   y => "AB9AAA40774D3CD476B52F82E7EE2D8A8D40CD88BF4...", #public key
   g => "2", # generator/base
   p => "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80D...", # prime
}

  params2hash
Since: CryptX-0.032

 my $params = $pk->params2hash;

 # returns hash like this (or undef if no key loaded):
 {
   g => "2", # generator/base
   p => "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80D...", # prime
}

FUNCTIONS

  dh_shared_secret
DH based shared secret generation. See method "shared_secret" below.

 #on Alice side
 my $shared_secret = dh_shared_secret('Alice_priv_dh1.key', 'Bob_pub_dh1.key');

 #on Bob side
 my $shared_secret = dh_shared_secret('Bob_priv_dh1.key', 'Alice_pub_dh1.key');

DEPRECATED INTERFACE
The following functions/methods were removed in removed in v0.049:

 encrypt
 decrypt
 sign_message
 verify_message
 sign_hash
 verify_hash

 dh_encrypt
 dh_decrypt
 dh_sign_message
 dh_verify_message
 dh_sign_hash
 dh_verify_hash

SEE ALSO

•   <https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange>