NAME

       ykchalresp - Perform challenge-response operation with YubiKey

SYNOPSIS

       ykchalresp [-1 | -2] [-H] [-Y] [-N] [-x] [-v] [-6] [-8] [-t] [-V] [-h]

DESCRIPTION

       Send  a challenge to a YubiKey, and read the response.  The YubiKey can be configured with
       two different C/R modes -- the standard one is a 160 bits HMAC-SHA1, and the  other  is  a
       YubiKey  OTP  mimicing  mode,  meaning  two  subsequent calls with the same challenge will
       result in different responses.

OPTIONS

       -1     send the challenge to slot 1.  This is the default.

       -2     send the challenge to slot 2.

       -H     send a 64 byte HMAC challenge.  This is the default.

       -Y     send a 6 byte Yubico OTP challenge.

       -N     non-blocking mode -- abort if the YubiKey is configured  to  require  a  key  press
              before sending the response.

       -x     challenge is hex encoded.

       -v     enable verbose mode.

       -6     output the response in OATH format, 6 digits.

       -8     output the response in OATH format, 8 digits.

       -t     use current time as challenge instead of reading challenge from command line (as in
              default TOTP mode, seconds since 1970-01-01 00:00:00 / 30  encoded  as  an  8  byte
              challenge).

       -V     print tool version and exit.

EXAMPLE

       The  YubiKey  challenge-response  operation can be demonstrated using the NIST PUB 198 A.2
       test vector.

       First, program a YubiKey with the test vector :

              $ ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -a 303132333435363738393a3b3c3d3e3f40414243
               ...
              Commit? (y/n) [n]: y
              $

       Now, send the NIST test challenge to  the  YubiKey  and  verify  the  result  matches  the
              expected :

              $ ykchalresp -2 'Sample #2'
              0922d3405faa3d194f82a45830737d5cc6c75d24
              $

BUGS

       Report ykchalresp bugs in the issue tracker ⟨https://github.com/Yubico/
       yubikey-personalization/issues⟩

SEE ALSO

       The ykpersonalize home page ⟨https://developers.yubico.com/yubikey-personalization/⟩

       YubiKeys can be obtained from Yubico ⟨http://www.yubico.com/⟩.