less ▁surve ill ance ▁controvers y , ▁Room ▁ 6 4 1 A , ▁the ▁F RA ▁and ▁so ▁on . ▁C rypto - an arch ists ▁consider ▁the ▁development ▁and ▁use ▁of ▁crypt ography ▁to ▁be ▁the ▁main ▁defense ▁against ▁such ▁problems , ▁as ▁opposed ▁to ▁political ▁action . ▁ ▁A ▁second ▁concern ▁is ▁ev asion ▁of ▁c ensor ship , ▁particularly ▁Internet ▁c ensor ship , ▁on ▁the ▁grounds ▁of ▁freedom ▁of ▁expression . ▁The ▁programs ▁used ▁by ▁c rypto - an arch ists ▁often ▁make ▁it ▁possible ▁to ▁both ▁publish ▁and ▁read ▁information ▁off ▁the ▁internet ▁or ▁other ▁computer ▁networks ▁an onym ously . ▁For ▁example , ▁Tor , ▁I 2 P , ▁F reen et ▁and ▁many ▁similar ▁networks ▁allow ▁for ▁anonymous ▁" hidden " ▁web pages ▁accessible ▁only ▁by ▁users ▁of ▁these ▁programs , ▁while ▁projects ▁like ▁Bit message ▁allow ▁for ▁anonymous ▁mess aging ▁system ▁intended ▁to ▁be ▁a ▁substitute ▁for ▁email . ▁This ▁helps ▁wh ist leb low ers ▁and ▁political ▁opposition ▁in ▁opp ress ive ▁nations ▁to ▁spread ▁their ▁information . ▁ ▁A ▁third ▁reason ▁is ▁to ▁build ▁and ▁particip ate ▁in ▁counter ▁econom ics , ▁which ▁includes ▁development ▁of ▁vi able ▁alternatives ▁to ▁bank ing ▁systems , ▁and ▁development ▁of ▁alternative ▁financial ▁systems ▁which ▁provide ▁the ▁user ▁with ▁options ▁for ▁greater ▁priv acy ▁or ▁an onym ity . ▁C rypt oc urr encies ▁such ▁as ▁Bit co in ▁and ▁services ▁like ▁Sil k ▁Road ▁and ▁Black ▁Market ▁Rel o aded ▁made ▁it ▁possible ▁to ▁trade