Initial data commit

Task/Playfair-cipher/J/playfair-cipher-1.j

@@ -0,0 +1,36 @@
+choose=: verb define
+  sel=. 'Q' e. y
+  alph=: (sel { 'JQ') -.~ a. {~ 65 + i.26
+  norm=: [: dedouble alph restrict ('I' I.@:=&'J'@]} ])`(-.&'Q')@.sel@toupper
+  ''
+)
+
+restrict=: ] -. -.~
+
+splitDigraph=: ,`([,'X',])@.((= {.) *. 2 | #@])
+dedouble=: splitDigraph/&.|.                     NB. progressively split digraphs in string
+
+choose 'Q'
+
+setkey=: verb define
+  key=. ~.norm y,alph
+  ref=: ,/ 2{."1 ~."1 (,"0/~ alph) ,"1 norm 'XQV'
+  mode=. #. =/"2 inds=. 5 5#:key i. ref
+  inds0=. (0 3,:2 1)&{@,"2 inds
+  inds1=. 5|1 0 +"1 inds NB. same column
+  inds2=. 5|0 1 +"1 inds NB. same row
+  alt=: key {~ 5 #. mode {"_1 inds0 ,"2 3 inds1 ,:"2 inds2
+  i. 0 0
+)
+
+pairs=: verb define
+  2{."1 -.&' '"1 ~."1 (_2]\ norm y) ,"1 'XQV'
+)
+
+encrypt=: verb define
+  ;:inv ;/ alt{~ref i. pairs y
+)
+
+decrypt=: verb define
+  , ref{~alt i. pairs y
+)

Task/Playfair-cipher/J/playfair-cipher-2.j

@@ -0,0 +1,7 @@
+   choose 'IJ'
+
+   setkey 'playfair example'
+   encrypt 'Hide the gold in the tree stump'
+BM OD ZB XD NA BE KU DM UI XM MO UV IF
+   decrypt 'BM OD ZB XD NA BE KU DM UI XM MO UV IF'
+HIDETHEGOLDINTHETREXESTUMP