Method of and circuit arrangement for securing teleprinter messages

Claim 1

IN A SYSTEM FOR DIRECTLY TRANSMITTING TELEPRINTER MESSAGES IN ACCORDANCE WITH THE FIVE-ELEMENT CODE, APPARATUS FOR SECURING SAID MESSAGES BY ALLOCATING TO EACH TWO FIVEELEMENT MESSAGE SYMBOLS A CONTROL SYMBOL LIKEWISE HAVING FIVE ELEMENTS AS DETERMINED BY AN INTERMEDIATE CONTROL SYSTEM, COMPRISING CODING MEANS FOR FORMING AN INTERMEDIATE SYMBOL FOR EACH INDIVIDUAL ELEMENT, DEPENDENT UPON THE NATURE OF SUCH ELEMENT, WHICH LIKEWISE HAS FIVE ELEMENTS, AT LEAST TWO OF WHICH HAVE THE SAME POLARITY AS THE ELEMENT TO BE SECURED, THEREBY ASSURING ALLOCATION OF THE SAME POLARITY IN CORRESPONDING MANNER FOR ALL ELEMENTS OF THE MESSAGE SYMBOLS, THE ELEMENTS OF SAID INTERMEDIATE SYMBOLS BEING ARRANGED IN PREDETERMINED CYCLIC PERMUTATION DEPENDENT UPON WHETHER THE MESSAGE SYMBOL INVOLVED IS THE FIRST OR SECOND OF TWO SYMBOLS TO BE SECURED, AND MEANS CONNECTED TO SAID CODING MEANS FOR RECEIVING THE ELEMENTS OF SAID INTERMEDIATE SYMBOLS IN PERMUTATED FORM AND ADDING CORRESPONDING ELEMENTS OF THE INTERMEDIATE CONTROL SYMBOLS FOR BOTH MESSAGE SYMBOLS, THEREBY FORMING SAID CONTROL SYMBOL FOR TRANSMISSION AFTER TRANSMISSION OF THE TWO MESSAGE SYMBOLS WHICH ARE TO BE SECURED.