README

== YubiKey C Client Library: libykclient ==

NOTE: This project is deprecated and is no longer being maintained. For more information and guidance on how to implement Yubico OTP support in applications, see https://status.yubico.com/2021/04/15/one-api-yubico-com-one-http-get/.

YubiKey C Client Library (libykclient) is a C library used to validate
an Yubikey OTP against Yubico's servers.  See
https://www.yubico.com[the Yubico website]
for more information about Yubico and the YubiKey.

=== Building ===

After downloading and unpacking the package tarball, you build it as
follows.

  ./configure
  make check
  sudo make install

=== Building from version controlled sources ===

Warning!  This is only for developers and if you don't understand what
you are doing, you should download the release files instead.

You may check out the sources using Git with the following command:

  git clone https://github.com/Yubico/yubico-c-client.git

This will create a directory 'yubico-c-client'.  Enter the directory:

  cd yubico-c-client

Recent versions of autoconf, automake and libtool must be installed.
Help2man is used to generate the manpages.  Libcurl development files
(headers and *.so) must also be installed.

Generate the build system using:

  autoreconf --install

Then refer to the user sections above regarding building.

=== Command-line tools ===

[CAUTION]
The ykclient command line tool is for testing/debugging purposes only.
Secret data, such as the client secret, should generally not be passed
as a command line argument in production. Doing so may expose the
value to other parts of the system.

There is one command line tool, ykclient, to validate a particular
OTP.  It needs a client id, which you can generate 
https://upgrade.yubico.com/getapikey[here].

Example usage:

[source, sh]
-----------
jas@mocca:~/src/yubico-c-client$ ./ykclient 
Usage: ./ykclient <client_id> <yubikey_otp>
 CLIENT_ID: your client id integer
 YUBIKEY_OTP: One-time password generated by yubikey
jas@mocca:~/src/yubico-c-client$ ./ykclient --debug 16 ccccccbchvthlivuitriujjifivbvtrjkjfirllluurj
Input:
  client id: 16
  token: ccccccbchvthlivuitriujjifivbvtrjkjfirllluurj
Verification output (2): Yubikey OTP was replayed (REPLAYED_OTP)
jas@mocca:~/src/yubico-c-client$ 
-----------

=== License ===

The project is licensed under a BSD license.  See the file COPYING for
exact wording.  For any copyright year range specified as YYYY-ZZZZ in
this package note that the range specifies every single year in that
closed interval.