▁into ▁each ▁other ▁using ▁the ▁properties ▁of ▁the ▁Schmidt ▁decomposition , ▁effectively ▁defe ating ▁the ▁binding ▁property . ▁ ▁One ▁subt le ▁assumption ▁of ▁the ▁proof ▁is ▁that ▁the ▁commit ▁phase ▁must ▁be ▁finished ▁at ▁some ▁point ▁in ▁time . ▁This ▁leaves ▁room ▁for ▁protocol s ▁that ▁require ▁a ▁continu ing ▁information ▁flow ▁until ▁the ▁bit ▁is ▁un ve iled ▁or ▁the ▁protocol ▁is ▁cancel led , ▁in ▁which ▁case ▁it ▁is ▁not ▁binding ▁anymore . ▁More ▁generally , ▁ ▁May ers ' ▁proof ▁applies ▁only ▁to ▁protocol s ▁that ▁explo it ▁quantum ▁physics ▁but ▁not ▁special ▁relativ ity . ▁Kent ▁has ▁shown ▁that ▁there ▁exist ▁un condition ally ▁secure ▁protocol s ▁for ▁bit ▁commit ment ▁that ▁explo it ▁the ▁principle ▁of ▁special ▁relativ ity ▁stating ▁that ▁information ▁cannot ▁travel ▁faster ▁than ▁light . ▁ ▁Comm it ments ▁based ▁on ▁physical ▁un cl on able ▁functions ▁Phys ical ▁un cl on able ▁functions ▁( PU F s ) ▁rely ▁on ▁the ▁use ▁of ▁a ▁physical ▁key ▁with ▁internal ▁random ness , ▁which ▁is ▁hard ▁to ▁clone ▁or ▁to ▁em ulate . ▁Electron ic , ▁optical ▁and ▁other ▁types ▁of ▁P U F s ▁have ▁been ▁discussed ▁extens ively ▁in ▁the ▁literature , ▁in ▁connection ▁with ▁their ▁potential ▁crypt ographic ▁applications ▁including ▁commit ment ▁schemes . ▁ ▁See ▁also ▁ ▁O bl iv ious ▁transfer ▁ ▁Acc um ulator ▁( c rypt ography ) ▁ ▁Key ▁signing ▁party ▁ ▁Web ▁of ▁trust ▁ ▁Z er oco in ▁ ▁References ▁ ▁External ▁links ▁Quant um