# phpman > perldoc > Crypt::PK::X25519

## NAME
    [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown) - Asymmetric cryptography based on X25519

## SYNOPSIS
     use [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown);

     #Shared secret
     my $priv = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new('Alice_priv_x25519.der');
     my $pub = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new('Bob_pub_x25519.der');
     my $shared_secret = $priv->shared_secret($pub);

     #Load key
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new;
     my $pk_hex = "EA7806F721A8570512C8F6EFB4E8D620C49A529E4DF5EAA77DEC646FB1E87E41";
     $pk->import_key_raw(pack("H*", $pk_hex), "public");
     my $sk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new;
     my $sk_hex = "002F93D10BA5728D8DD8E9527721DABA3261C0BB1BEFDE7B4BBDAC631D454651";
     $sk->import_key_raw(pack("H*", $sk_hex), "private");

     #Key generation
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new->generate_key;
     my $private_der = $pk->export_key_der('private');
     my $public_der  = $pk->export_key_der('public');
     my $private_pem = $pk->export_key_pem('private');
     my $public_pem  = $pk->export_key_pem('public');
     my $private_raw = $pk->export_key_raw('private');
     my $public_raw  = $pk->export_key_raw('public');
     my $private_jwk = $pk->export_key_jwk('private');
     my $public_jwk  = $pk->export_key_jwk('public');

## DESCRIPTION
    *Since: CryptX-0.067*

## METHODS
  new
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new();
     #or
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new($priv_or_pub_key_filename);
     #or
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new(\$buffer_containing_priv_or_pub_key);

    Support for password protected PEM keys

     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new($priv_pem_key_filename, $password);
     #or
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new(\$buffer_containing_priv_pem_key, $password);

  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;

  import_key
    Loads private or public key in DER or PEM format.

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

    Support for password protected PEM keys:

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

    Loading private or public keys form perl hash:

     $pk->import_key($hashref);

     # the $hashref is either a key exported via key2hash
     $pk->import_key({
          curve => "x25519",
          pub   => "EA7806F721A8570512C8F6EFB4E8D620C49A529E4DF5EAA77DEC646FB1E87E41",
          priv  => "002F93D10BA5728D8DD8E9527721DABA3261C0BB1BEFDE7B4BBDAC631D454651",
     });

     # or a hash with items corresponding to JWK (JSON Web Key)
     $pk->import_key({
           kty => "OKP",
           crv => "X25519",
           d   => "AC-T0Qulco2N2OlSdyHaujJhwLsb7957S72sYx1FRlE",
           x   => "6ngG9yGoVwUSyPbvtOjWIMSaUp5N9eqnfexkb7HofkE",
     });

    Supported key formats:

     # all formats can be loaded from a file
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new($filename);

     # or from a buffer containing the key
     my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new(\$buffer_with_key);

    *   X25519 private keys in PEM format

         -----BEGIN X25519 PRIVATE KEY-----
         MC4CAQAwBQYDK2VuBCIEIAAvk9ELpXKNjdjpUnch2royYcC7G+/ee0u9rGMdRUZR
         -----END X25519 PRIVATE KEY-----

    *   X25519 private keys in password protected PEM format

         -----BEGIN X25519 PRIVATE KEY-----
         Proc-Type: 4,ENCRYPTED
         DEK-Info: DES-CBC,DEEFD3D6B714E75A

         dfFWP5bKn49aZ993NVAhQQPdFWgsTb4j8CWhRjGBVTPl6ITstAL17deBIRBwZb7h
         pAyIka81Kfs=
         -----END X25519 PRIVATE KEY-----

    *   X25519 public keys in PEM format

         -----BEGIN PUBLIC KEY-----
         MCowBQYDK2VuAyEA6ngG9yGoVwUSyPbvtOjWIMSaUp5N9eqnfexkb7HofkE=
         -----END PUBLIC KEY-----

    *   PKCS#8 private keys

         -----BEGIN PRIVATE KEY-----
         MC4CAQAwBQYDK2VuBCIEIAAvk9ELpXKNjdjpUnch2royYcC7G+/ee0u9rGMdRUZR
         -----END PRIVATE KEY-----

    *   PKCS#8 encrypted private keys

         -----BEGIN ENCRYPTED PRIVATE KEY-----
         MIGHMEsGCSqGSIb3DQEFDTA+MCkGCSqGSIb3DQEFDDAcBAiS0NOFZmjJswICCAAw
         DAYIKoZIhvcNAgkFADARBgUrDgMCBwQIGd40Hdso8Y4EONSRCTrqvftl9hl3zbH9
         2QmHF1KJ4HDMdLDRxD7EynonCw2SV7BO+XNRHzw2yONqiTybfte7nk9t
         -----END ENCRYPTED PRIVATE KEY-----

    *   X25519 private keys in JSON Web Key (JWK) format

        See <<https://tools.ietf.org/html/rfc8037>>

         {
          "kty":"OKP",
          "crv":"X25519",
          "x":"6ngG9yGoVwUSyPbvtOjWIMSaUp5N9eqnfexkb7HofkE",
          "d":"AC-T0Qulco2N2OlSdyHaujJhwLsb7957S72sYx1FRlE",
         }

        BEWARE: For JWK support you need to have JSON module installed.

    *   X25519 public keys in JSON Web Key (JWK) format

         {
          "kty":"OKP",
          "crv":"X25519",
          "x":"6ngG9yGoVwUSyPbvtOjWIMSaUp5N9eqnfexkb7HofkE",
         }

        BEWARE: For JWK support you need to have JSON module installed.

  import_key_raw
    Import raw public/private key - can load raw key data exported by "export_key_raw".

     $pk->import_key_raw($key, 'public');
     $pk->import_key_raw($key, 'private');

  export_key_der
     my $private_der = $pk->export_key_der('private');
     #or
     my $public_der = $pk->export_key_der('public');

  export_key_pem
     my $private_pem = $pk->export_key_pem('private');
     #or
     my $public_pem = $pk->export_key_pem('public');

    Support for password protected PEM keys

     my $private_pem = $pk->export_key_pem('private', $password);
     #or
     my $private_pem = $pk->export_key_pem('private', $password, $cipher);

     # supported ciphers: 'DES-CBC'
     #                    'DES-EDE3-CBC'
     #                    'SEED-CBC'
     #                    'CAMELLIA-128-CBC'
     #                    'CAMELLIA-192-CBC'
     #                    'CAMELLIA-256-CBC'
     #                    'AES-128-CBC'
     #                    'AES-192-CBC'
     #                    'AES-256-CBC' (DEFAULT)

  export_key_jwk
    Exports public/private keys as a JSON Web Key (JWK).

     my $private_json_text = $pk->export_key_jwk('private');
     #or
     my $public_json_text = $pk->export_key_jwk('public');

    Also exports public/private keys as a perl HASH with JWK structure.

     my $jwk_hash = $pk->export_key_jwk('private', 1);
     #or
     my $jwk_hash = $pk->export_key_jwk('public', 1);

    BEWARE: For JWK support you need to have JSON module installed.

  export_key_raw
    Export raw public/private key

     my $private_bytes = $pk->export_key_raw('private');
     #or
     my $public_bytes = $pk->export_key_raw('public');

  shared_secret
      # Alice having her priv key $pk and Bob's public key $pkb
      my $pk  = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new($priv_key_filename);
      my $pkb = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new($pub_key_filename);
      my $shared_secret = $pk->shared_secret($pkb);

      # Bob having his priv key $pk and Alice's public key $pka
      my $pk = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new($priv_key_filename);
      my $pka = [Crypt::PK::X25519](https://www.chedong.com/phpMan.php/perldoc/Crypt%3A%3APK%3A%3AX25519/markdown)->new($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

  key2hash
     my $hash = $pk->key2hash;

     # returns hash like this (or undef if no key loaded):
     {
       curve => "x25519",
       # raw public key as a hexadecimal string
       pub   => "EA7806F721A8570512C8F6EFB4E8D620C49A529E4DF5EAA77DEC646FB1E87E41",
       # raw private key as a hexadecimal string. undef if key is public only
       priv  => "002F93D10BA5728D8DD8E9527721DABA3261C0BB1BEFDE7B4BBDAC631D454651",
     }

## SEE ALSO
    *   <<https://en.wikipedia.org/wiki/Curve25519>>

    *   <<https://tools.ietf.org/html/rfc7748>>