RosettaCodeData/Task/Playfair-cipher/J/playfair-cipher-1.j
2023-07-01 13:44:08 -04:00

36 lines
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Text

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
)