op oe ) ▁( D ale kop is owe ▁Ur ząd zenie ▁Do ▁Ele ktr onic zn ego ▁K od owania ▁-- ▁Tele pr inter ▁Device ▁for ▁Electron ic ▁C oding ) ▁was ▁an ▁on - line ▁and ▁off - line ▁encryption ▁system ▁developed ▁during ▁the ▁Cold ▁War ▁in ▁the ▁ 1 9 6 0 s ▁in ▁the ▁Polish ▁People ' s ▁Republic ▁by ▁the ▁Tel kom ▁Te let ra ▁company ▁and ▁the ▁Ministry ▁of ▁Inter ior ▁for ▁use ▁on ▁tele pr inter ▁circ uits . ▁The ▁units ▁saw ▁use ▁in ▁the ▁Polish ▁Minister stwo ▁Sp raw ▁W ewnętrz nych ▁networks ▁serving ▁the ▁ ▁( Mil ic ja ▁O by w atel ska ), ▁the ▁( S łuż ba ▁Bez pie cze ńst wa ), ▁the ▁Polish ▁Ministry ▁of ▁National ▁Def ense ▁( Min ister stwo ▁O br ony ▁Narod owej ), ▁the ▁Ministry ▁of ▁Foreign ▁Affairs ▁( Min ister stwo ▁Sp raw ▁Zag ran icz nych ) ▁and ▁the ▁National ▁Bank ▁of ▁Poland ▁( N arod owy ▁Bank ▁Polski ). ▁The ▁Pol es ▁also ▁pressed ▁Wars aw ▁P act ▁states ▁to ▁adopt ▁the ▁D U DE K ▁sets ▁for ▁international ▁traffic . ▁ ▁The ▁D U DE K ▁series ▁used ▁random ▁symmetric ▁keys ▁provided ▁on ▁paper ▁t apes , ▁which ▁were ▁X OR ed ▁by ▁the ▁unit ▁with ▁the ▁plain text ▁provided ▁from ▁the ▁tele pr inter ▁or ▁recorded ▁on ▁different ▁paper ▁t apes . ▁The ▁D U DE K ▁sets ▁were ▁to ▁be ▁used ▁in ▁conj unction ▁with ▁tele pr inter