Internal Program Version: libidn  1.43

GNU Libidn is an implementation of the Stringprep, Punycode, and IDNA
specifications defined by the IETF Internationalized Domain Names
(IDN) working group. It is used to prepare internationalized strings
(such as domain name labels, usernames, and passwords) in order to
increase the likelihood that string input and string comparison work
in ways that make sense for typical users around the world. The
library contains a generic Stringprep implementation that does
Unicode 3.2 NFKC normalization, mapping and prohibition of
characters, and bidirectional character handling. Profiles for iSCSI,
Kerberos 5, Nameprep, SASL, and XMPP are included. Punycode and ASCII
Compatible Encoding (ACE) via IDNA is supported.

http://www.gnu.org/software/libidn