The cryptographic unit operates in response to a specific authorized user giving {HEAD ~ permission} to undertake a specific cryptographic operation on data input to the BCU only upon the specific authorized user being determined as an authorized BCU user, whereby {TAIL ~ a specific private key} corresponding to the specific authorized user is enabled for use in the specific cryptographic operation after which the specific private key is disabled 
The cryptographic unit operates in response to a specific authorized user giving { HEAD ~ permission } to undertake a specific cryptographic operation on data input to the BCU only upon the specific authorized user being determined as an authorized BCU user , whereby { TAIL ~ a specific private key } corresponding to the specific authorized user is enabled for use in the specific cryptographic operation after which the specific private key is disabled
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH