yubikey-totp (1)

yubikey-totp [-v] [-h] [--time | --step] [--digits] [--slot] [--debug]

OATH codes are one time passwords (OTP) calculated in a standardized way. While the YubiKey is primarily used with Yubico OTP's, the YubiKey is also capable of producing OATH codes.

OATH generally comes in two flavors -- event based (called HOTP) and time based (called TOTP). Since the YubiKey does not contain a battery, it cannot keep track of the current time itself and therefor a helper application such as yubikey-totp is required to effectively send the current time to the YubiKey, which can then perform the cryptographic calculation needed to produce the OATH code.

Through the use of a helper application, such as yubikey-totp, the YubiKey can be used with sites offering OATH TOTP authentication, such as Google GMail.

-v

enable verbose mode.

-h

show help

--time

specify the time value to use (in seconds since epoch)

--step

how frequent codes change in your system - typically 30 or 60 seconds

--digits

digits in OATH code - typically 6

--slot

YubiKey slot to use - default 2

--debug

enable debug output

The YubiKey OATH TOTP operation can be demonstrated using the RFC 6238 test key "12345678901234567890" (ASCII).

First, program a YubiKey for HMAC-SHA1 Challenge-Response operation with the test vector HMAC key :

$ ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -o serial-api-visible \
	-a 3132333435363738393031323334353637383930

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

$ yubikey-totp --step 30 --digits 8 --time 1111111109
07081804
$

Report yubikey-totp bugs in \$2 \(laURL: \$1 \(ra\$3

YubiKeys can be obtained from