ykchalresp - Perform challenge-response operation with YubiKey
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 mimicking mode, meaning two subsequent calls with the same challenge will result in different responses.
- -nkey
-
send the challenge to the nth key found.
- -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).
- -iFILE
-
take challenge from FILE instead of as an argument. If file is - challenge is read from STDIN
- -V
-
print tool version and exit.
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 -a303132333435363738393a3b3c3d3e3f40414243
...
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
$Report ykchalresp bugs in the issue tracker https://github.com/Yubico/yubikey-personalization/issues
The ykpersonalize home page https://developers.yubico.com/yubikey-personalization/
YubiKeys can be obtained from Yubico http://www.yubico.com/