### Appears on

Assembled by Tim Ward from many sources. Contains programs 10176 – 10210.

### Source Code

10 REM "CYPHER" 40 FAST 50 DIM A(26,26) 60 LET J=-1 70 FOR I=1 TO 26 80 LET J=J+1 90 FOR K=1 TO 26 100 LET A(I,K)=K+J 110 IF A(I,K)>26 THEN LET A(I,K)=A(I,K)-26 120 NEXT K 130 NEXT I 150 PRINT 160 PRINT 170 SLOW 180 PRINT " ENTER KEYWORD" 190 INPUT K$ 200 PRINT K$ 210 PRINT 220 PRINT " ENTER MESSAGE" 230 INPUT M$ 240 PRINT M$ 250 PRINT 260 PRINT " ENCYPHER/DECYPHER? (ENTER E OR D)" 270 INPUT Q$ 280 PRINT 290 IF Q$="E" THEN GOTO 320 300 IF Q$="D" THEN GOTO 440 310 IF Q$<>"E" OR Q$<>"D" THEN GOTO 260 330 FAST 340 PRINT " ENCYPHERED MESSAGE READS:-" 350 PRINT 360 LET S=0 370 LET T=0 380 LET S=S+1 390 IF S>LEN K$ THEN LET S=S-LEN K$ 400 LET T=T+1 410 PRINT CHR$ (37+A(CODE K$(S)-37,CODE M$(T)-37)); 420 IF T=LEN M$ THEN GOTO 140 430 GOTO 380 450 FAST 460 LET Z=0 470 PRINT " DECYPHERED MESSAGE READS:-" 480 PRINT 490 FOR W=1 TO LEN M$ 500 LET Z=Z+1 510 IF Z>LEN K$ THEN LET Z=Z-LEN K$ 520 FOR X=1 TO 26 530 IF A(CODE K$(Z)-37,X)=CODE M$(W)-37 THEN PRINT CHR$ (X+37); 540 NEXT X 550 NEXT W 560 GOTO 140 570 SAVE "1017%7" 580 RUN