▁min ing ▁machines . ▁Although ▁most ▁crypt oc urr encies ▁use ▁the ▁S HA - 2 5 6 ▁hash ▁function , ▁the ▁same ▁AS IC ▁technology ▁could ▁be ▁used ▁to ▁create ▁hash c ash ▁sol vers ▁that ▁are ▁three ▁orders ▁of ▁magnitude ▁faster ▁than ▁a ▁consumer ▁CPU , ▁reducing ▁the ▁computational ▁hur d le ▁for ▁sp amm ers . ▁ ▁App lications ▁ ▁Bit co in ▁min ing ▁In ▁contrast ▁to ▁hash c ash ▁in ▁mail ▁applications ▁that ▁re lies ▁on ▁recip ients ▁to ▁set ▁manually ▁an ▁amount ▁of ▁work ▁intended ▁to ▁d eter ▁mal icious ▁send ers , ▁the ▁Bit co in ▁crypt oc urrency ▁network ▁emp lo ys ▁a ▁different ▁has hing - based ▁proof - of - work ▁challenge ▁to ▁enable ▁compet itive ▁bit co in ▁min ing . ▁A ▁bit co in ▁min er ▁runs ▁a ▁computer ▁program ▁that ▁collect s ▁un conf ir med ▁transactions ▁from ▁coin ▁deal ers ▁in ▁the ▁network . ▁With ▁other ▁data ▁these ▁can ▁form ▁a ▁block ▁and ▁ear n ▁a ▁payment ▁to ▁the ▁min er , ▁but ▁a ▁block ▁is ▁accepted ▁by ▁the ▁network ▁only ▁when ▁the ▁min er ▁disco vers ▁by ▁trial ▁and ▁error ▁a ▁" non ce " ▁number ▁that ▁when ▁included ▁in ▁the ▁block ▁yields ▁a ▁hash ▁with ▁a ▁sufficient ▁number ▁of ▁leading ▁zero ▁bits ▁to ▁meet ▁the ▁network ' s ▁difficulty ▁target . ▁Block s ▁accepted ▁from ▁min ers ▁form ▁the ▁bit co in ▁block chain ▁that ▁is ▁a ▁growing ▁led ger ▁of ▁every ▁bit co in ▁transaction ▁since