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.\"     Title: ykchalresp
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: Version 1.17.3
.\"    Manual: YubiKey Personalization Tool Manual
.\"    Source: ykchalresp
.\"  Language: English
.\"
.TH "YKCHALRESP" "1" "Version 1\&.17\&.3" "ykchalresp" "YubiKey Personalization Tool M"
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.SH "NAME"
ykchalresp \- Perform challenge\-response operation with YubiKey
.SH "SYNOPSIS"
.sp
\fBykchalresp\fR [\fI\-1\fR | \fI\-2\fR] [\fI\-H\fR | \fI\-Y\fR] [\fI\-N\fR] [\fI\-x\fR] [\fI\-v\fR] [\fI\-6\fR | \fI\-8\fR] [\fI\-t\fR] [\fI\-V\fR] [\fI\-h\fR]
.SH "DESCRIPTION"
.sp
Send a challenge to a YubiKey, and read the response\&. The YubiKey can be configured with two different C/R modes \(em 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\&.
.SH "OPTIONS"
.PP
\fB\-1\fR
.RS 4
send the challenge to slot 1\&. This is the default
.RE
.PP
\fB−2\fR
.RS 4
send the challenge to slot 2\&.
.RE
.PP
\fB\-H\fR
.RS 4
send a 64 byte HMAC challenge\&. This is the default\&.
.RE
.PP
\fB\-Y\fR
.RS 4
send a 6 byte Yubico OTP challenge\&.
.RE
.PP
\fB\-N\fR
.RS 4
non\-blocking mode \(em abort if the YubiKey is configured to require a key press before sending the response\&.
.RE
.PP
\fB\-x\fR
.RS 4
challenge is hex encoded\&.
.RE
.PP
\fB\-v\fR
.RS 4
enable verbose mode\&.
.RE
.PP
\fB\-6\fR
.RS 4
output the response in OATH format, 6 digits\&.
.RE
.PP
\fB\-8\fR
.RS 4
output the response in OATH format, 8 digits\&.
.RE
.PP
\fB\-t\fR
.RS 4
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)\&.
.RE
.PP
\fB\-V\fR
.RS 4
print tool version and exit\&.
.RE
.SH "EXAMPLE"
.sp
The YubiKey challenge\-response operation can be demonstrated using the \fBNIST PUB 198 A\&.2\fR test vector\&.
.sp
First, program a YubiKey with the test vector :
.sp
.if n \{\
.RS 4
.\}
.nf
$ ykpersonalize \-2 \-ochal\-resp \-ochal\-hmac \-ohmac\-lt64 \-a 303132333435363738393a3b3c3d3e3f40414243
 \&.\&.\&.
Commit? (y/n) [n]: y
$
.fi
.if n \{\
.RE
.\}
.sp
Now, send the NIST test challenge to the YubiKey and verify the result matches the expected :
.sp
.if n \{\
.RS 4
.\}
.nf
$ ykchalresp \-2 \*(AqSample #2\*(Aq
0922d3405faa3d194f82a45830737d5cc6c75d24
$
.fi
.if n \{\
.RE
.\}
.SH "BUGS"
.sp
Report ykchalresp bugs in the issue tracker (https://github\&.com/Yubico/yubikey\-personalization/issues)
.SH "SEE ALSO"
.sp
The ykpersonalize home page ⟨ URL: https://developers\&.yubico\&.com/yubikey\-personalization/ ⟩
.sp
YubiKeys can be obtained from Yubico ⟨ URL: http://www\&.yubico\&.com/ ⟩ \&.