▁ 1 : 2 0 : 1 3 0 3 0 3 0 6 0 0 : ad am @ cy ph ers pace . org :: Mc My b Z I h x K X u 5 7 jd : ck vi ▁ ▁The ▁header ▁contains : ▁ ▁ver : ▁Hash c ash ▁format ▁version , ▁ 1 ▁( which ▁su pers edes ▁version ▁ 0 ). ▁ ▁bits : ▁Number ▁of ▁" partial ▁pre - image " ▁( zero ) ▁bits ▁in ▁the ▁hash ed ▁code . ▁ ▁date : ▁The ▁time ▁that ▁the ▁message ▁was ▁sent , ▁in ▁the ▁format ▁. ▁ ▁resource : ▁Resource ▁data ▁string ▁being ▁transm itted , ▁e . g ., ▁an ▁IP ▁address ▁or ▁email ▁address . ▁ ▁ext : ▁Ext ension ▁( optional ; ▁ignored ▁in ▁version ▁ 1 ). ▁ ▁rand : ▁String ▁of ▁random ▁characters , ▁encoded ▁in ▁base - 6 4 ▁format . ▁ ▁counter : ▁Binary ▁counter , ▁encoded ▁in ▁base - 6 4 ▁format . ▁ ▁The ▁header ▁contains ▁the ▁recip ient ' s ▁email ▁address , ▁the ▁date ▁of ▁the ▁message , ▁and ▁information ▁prov ing ▁that ▁the ▁required ▁computation ▁has ▁been ▁performed . ▁The ▁presence ▁of ▁the ▁recip ient ' s ▁email ▁address ▁requires ▁that ▁a ▁different ▁header ▁be ▁computed ▁for ▁each ▁recip ient . ▁The ▁date ▁allows ▁the ▁recip ient ▁to ▁record ▁headers ▁received ▁recently ▁and ▁to ▁ensure ▁that ▁the ▁header ▁is ▁unique ▁to ▁the ▁email ▁message . ▁ ▁S ender ' s ▁side ▁The ▁sender