%!PS-Adobe-2.0
/r 360 26 div def
/inch { 72 mul} def
/Tempstr 2 string def
/Helvetica-Bold findfont 18 scalefont setfont
/radius 120 def

/circleofLetters {   
 [(A) (B) (C) (D) (E) (F) (G) (H) (I) (J)
  (K) (L) (M) (N) (O) (P) (Q) (R) (S) (T)
  (U) (V) (W) (X) (Y) (Z)]
  /ary exch def % the array of letters

  0 1 25{ % from 0 to 25 in steps of 1
    /ind exch def % the for loop value
    gsave
      ind r mul neg rotate % rotate by (for loop value)*360/26
      ary ind get stringwidth pop 2 div neg radius 30 add moveto
      ary ind get show
      % convert ind to string, store in Tempstr, using cvs
      ind Tempstr cvs stringwidth pop 2 div neg radius 10 add moveto
      ind Tempstr cvs show
      3 setlinewidth
      0 radius 50 add moveto 0 20 rlineto stroke
    grestore
  } for
}def

/circles {
   3 setlinewidth
   0 0 radius 60 add 0 360 arc stroke
   0 0 6 0 360 arc stroke
   1 setlinewidth 
   0 0 radius 80 add 0 360 arc [5 3] 0 setdash stroke
} def

/arrowhead {
  newpath 0 radius 78 add moveto
  -5 -12 rlineto 10 0 rlineto closepath fill
} def

8.5 inch 2 div 11 inch 2 div translate
circleofLetters
circles
arrowhead
/Helvetica-Bold findfont 13 scalefont setfont
-45 50 moveto (Inner letters are) show
-60 35 moveto (plaintext characters) show
-80 -50 moveto (Set arrow on pad character) show
-75 radius 100 add neg moveto ((Cut along dashed line.))show
showpage