YubiKey C Library: libyubikey
=============================

This package make up the low-level C software development kit for the
Yubico YubiKey authentication device.  See https://www.yubico.com/ for
more information about Yubico and the YubiKey.

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.

Building
--------

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

  ./configure
  make check
  sudo make install

Another way to build the package is with a hand written short
makefile, invoke using 'make -f simple.mk check'.  This is usually not
recommended, and you will have to read simple.mk for further
information.

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 git://github.com/Yubico/yubico-c.git

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

  cd yubico-c

Recent versions of autoconf, automake and libtool must be installed,
if you want to use the normal ./configure based approach.  Use
simple.mk if you don't want this step.

Generate the build system:

  autoreconf --install

Then refer to the user sections above regarding building.

Command-line tools
------------------

The "modhex" program converts data between modhex, normal hex, and
binary form.

The "ykparse" program decrypts and parses one OTP given the OTP and
the AES key corresponding to that YubiKey.

The "ykgenerate" program constructs and encrypts one OTP given AES key
and internal data values.

Example usage:

-------
  $ ./modhex test
  ifhgieif
  $ ./modhex -d ifhgieif; echo
  test
  $ ./modhex -h b565716f
  nghgibhv
  $ ./modhex -h -d nghgibhv
  b565716f
  $ ./ykparse ecde18dbe76fbd0c33330f1c354871db dteffujedcflcindvdbrblehecuitvjkjevvehjd
  warning: overlong token, ignoring prefix: dteffuje
  Input:
    token: dcflcindvdbrblehecuitvjkjevvehjd
            20 4a 07 b2 f2 1c 1a 36 30 e7 df 89 83 ff 36 82
    aeskey: ecde18dbe76fbd0c33330f1c354871db
            ec de 18 db e7 6f bd 0c 33 33 0f 1c 35 48 71 db
  Output:
            87 92 eb fe 26 cc 13 00 a8 c0 00 10 b4 08 6f 5b

  Struct:
    uid: 87 92 eb fe 26 cc
    counter: 19 (0x0013)
    timestamp (low): 49320 (0xc0a8)
    timestamp (high): 0 (0x00)
    session use: 16 (0x10)
    random: 2228 (0x8b4)
    crc: 23407 (0x5b6f)

  Derived:
    cleaned counter: 19 (0x0013)
    modhex uid: jikdunvudhrr
    triggered by caps lock: no
    crc: F0B8
    crc check: ok
  $ ./ykparse ecde18dbe76fbd0c33330f1c354871db dteffujehknhfjbrjnlnldnhcujvddbikngjrtgh
  warning: overlong token, ignoring prefix: dteffuje
  Input:
    token: hknhfjbrjnlnldnhcujvddbikngjrtgh
            69 b6 48 1c 8b ab a2 b6 0e 8f 22 17 9b 58 cd 56
    aeskey: ecde18dbe76fbd0c33330f1c354871db
            ec de 18 db e7 6f bd 0c 33 33 0f 1c 35 48 71 db
  Output:
            87 92 eb fe 26 cc 13 00 30 c2 00 11 c8 9f 23 c8

  Struct:
    uid: 87 92 eb fe 26 cc
    counter: 19 (0x0013)
    timestamp (low): 49712 (0xc230)
    timestamp (high): 0 (0x00)
    session use: 17 (0x11)
    random: 40904 (0x9fc8)
    crc: 51235 (0xc823)

  Derived:
    cleaned counter: 19 (0x0013)
    modhex uid: jikdunvudhrr
    triggered by caps lock: no
    crc: F0B8
    crc check: ok
  $ ./ykgenerate ecde18dbe76fbd0c33330f1c354871db 8792ebfe26cc 0013 c0a8 00 10
  hcfktknicvbcnhbkvigcfhgddhhhrknc
  $ ./ykparse ecde18dbe76fbd0c33330f1c354871db `./ykgenerate ecde18dbe76fbd0c33330f1c354871db 8792ebfe26cc 0013 c0a8 00 10`
  Input:
    token: lihggvrgffbjnrehcgnkvknjkvubeekr
            a7 65 5f c5 44 18 bc 36 05 b9 f9 b8 9f e1 33 9c
    aeskey: ecde18dbe76fbd0c33330f1c354871db
            ec de 18 db e7 6f bd 0c 33 33 0f 1c 35 48 71 db
  Output:
            87 92 eb fe 26 cc 13 00 a8 c0 00 10 95 44 ec e9

  Struct:
    uid: 87 92 eb fe 26 cc
    counter: 19 (0x0013)
    timestamp (low): 49320 (0xc0a8)
    timestamp (high): 0 (0x00)
    session use: 16 (0x10)
    random: 17557 (0x4495)
    crc: 59884 (0xe9ec)

  Derived:
    cleaned counter: 19 (0x0013)
    modhex uid: jikdunvudhrr
    triggered by caps lock: no
    crc: F0B8
    crc check: ok
  $
-------