phpsec/phpSec — Issue #75: phpsecYubikey::getYubikeyId() is broken
Author: xqus
Created: 2011-12-19 20:26:02+00:00
State: open

The identity part is the same for every OTP, and it is the initial 2-16 modhex characters of the OTP. (The identity can be programmed to 0 characters, but then obviously this scheme does not apply.) Since the rest of the OTP is always 32 characters, the method to extract the identity is to remove 32 characters from the end and then use the remaining string, which should be 2-16 characters, as the YubiKey identity.

http://code.google.com/p/yubikey-val-server-php/wiki/GettingStartedWritingClients