# phpman > perldoc > Net::IDN::Punycode

## NAME
    [Net::IDN::Punycode](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3AIDN%3A%3APunycode/markdown) - A Bootstring encoding of Unicode for IDNA (RFC 3492)

## SYNOPSIS
      use [Net::IDN::Punycode](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3AIDN%3A%3APunycode/markdown) qw(:all);
      $punycode = encode_punycode($unicode);
      $unicode  = decode_punycode($punycode);

## DESCRIPTION
    This module implements the Punycode encoding, and only the Punycode encoding.

    This module does not implement any other steps required for converting internationalized domain
    names (IDNs) to and from ASCII. In particular, it does not do any string preparation as
    specified by *Nameprep*/*IDNA2008*/*PRECIS* and does not add nor remove the ACE prefix ("xn--").
    Thus, use [Net::IDN::Encode](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3AIDN%3A%3AEncode/markdown) if you want to convert domain names.

    Punycode is an instance of a more general algorithm called Bootstring, which allows strings
    composed from a small set of "basic" code points to uniquely represent any string of code points
    drawn from a larger set. Punycode is Bootstring with particular parameter values appropriate for
    IDNA.

## WARNING
    You may be tempted to use this module directly and add/remove the ACE prefix ("xn--") in your
    code for performance reasons. Usually, this is not a good idea. If you convert domain labels (or
    other strings) without proper preparation, you may end up with an ASCII encoding that is not
    interoperable or even poses security issues due to spoofing.

    Even if you think that your domain names are valid and already mapped to the correct form, this
    may not be true. For example, some environments might automatically convert your perfectly valid
    domain names to a different but equivalent Unicode normalization form (e.g., NFD instead of
    NFC), which already breaks IDNA.

## FUNCTIONS
    No functions are exported by default. You can use the tag ":all" or import them individually.

    The following functions are available:

### encode_punycode
        Encodes $input with Punycode and returns the result.

        This function will throw an exception on invalid/unencodable input.

### decode_punycode
        Decodes $input with Punycode and returns the result.

        This function will throw an exception on invalid input.

## AUTHORS
    Tatsuhiko Miyagawa <<miyagawa@bulknews.net>> (versions 0.01 to 0.02)

    Claus Färber <<CFAERBER@cpan.org>> (versions 1.000 and higher)

## LICENSE
    Copyright 2002-2004 Tatsuhiko Miyagawa <<miyagawa@bulknews.net>>

    Copyright 2007-2014 Claus Färber <<CFAERBER@cpan.org>>

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

## SEE ALSO
    RFC 3492 (<<http://www.ietf.org/rfc/rfc3492.txt>>), [IETF::ACE](https://www.chedong.com/phpMan.php/perldoc/IETF%3A%3AACE/markdown), [Convert::RACE](https://www.chedong.com/phpMan.php/perldoc/Convert%3A%3ARACE/markdown)