Playfair cipher: Difference between revisions

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=={{header|zkl}}==

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<lang zkl>fcn genKeyTable(key,deadChr){ // deadChr=="Q" or "J"

Punting Q out of the alphabet.

deadChr=deadChr.toUpper();

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<lang zkl>fcn genKeyTable(key){

key=(key ~~- " qQ")~~.toUpper().unique();

key=key.toUpper().unique() - " " - deadChr;

key + (["A".."Z"].~~aggregate~~(String~~).walk(~~) - ~~"Q"~~ - key);

return(key + (["A".."Z"].pump(String) - deadChr - key), deadChr);

}</lang>

<lang zkl>fcn playfair(text,~~keyTable~~){ // text is a-z only

<lang zkl>fcn playfair(text,keytable){ // text is a-z only

keyTable,deadChr:=keytable;

text=text.toUpper();

text-=text - keyTable; // remove unencodable characters

if(~~text.len().isOdd~~) text+="Z";

if(deadChr=="Q") text-=deadChr; else text=text.replace("J","I");

row:='wrap(c){ keyTable.index(c)/5 };

col:='wrap(c){ keyTable.index(c)%5 };

ltrRight:='wrap(c){ keyTable[(keyTable.index(c)+1)%25] };

ltrRight:='wrap(c){ keyTable[(keyTable.index(c) + 1)%25] };

ltrBelow:='wrap(c){ keyTable[(keyTable.index(c)+5)%25] };

ltrBelow:='wrap(c){ keyTable[(keyTable.index(c) + 5)%25] };

ltrAt:='wrap(r,c){ keyTable[r*5+c] };

ltrAt:='wrap(r,c) { keyTable[r*5 + c] };

(text.toUpper()-"Q").pump(String,Void.Read, //-->digraph

~~'wrap~~(~~a,b~~){

sink:=Sink(String);

foreach a in (text){

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~~if(a==b)~~ b="X";

b:=__aWalker._next() and __aWalker.value or "X";

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if((ra:=row(a))==(rb:=row(b))) ~~return(~~ltrRight(a)+ltrRight(b));

if(a==b){

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if((ca:=col(a))==(cb:=col(b))) ~~return(~~ltrBelow(a)+ltrBelow(b));

if(b=="X"){ // "XX" is pathological

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~~return(~~ltrAt(ra,cb)+ltrAt(rb,ca));

if(not __aWalker.atEnd) __aWalker.push(b);

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});

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b="Z";

}

else { __aWalker.push(b); b="X"; }

}

sink.write(

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if((ra:=row(a))==(rb:=row(b))) ltrRight(a) + ltrRight(b);

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else if((ca:=col(a))==(cb:=col(b))) ltrBelow(a) + ltrBelow(b);

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else ltrAt(ra,cb) + ltrAt(rb,ca);

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);

}

sink.close()

.pump(String,Void.Read,"".create.fp(" ")).strip(); // insert blanks

}</lang>

<lang zkl>fcn decodePF(text,keyTable){

keyTable,_=keyTable;

text-=" ";

row:='wrap(c){ keyTable.index(c)/5 };

col:='wrap(c){ keyTable.index(c)%5 };

ltrLeft:='wrap(c){ keyTable[(keyTable.index(c)-1)%25] };

ltrLeft:='wrap(c){ keyTable[(keyTable.index(c) - 1)%25] };

ltrUp:='wrap(c){ n:=keyTable.index(c)-5; if(n<0)n+=25; keyTable[n%25] };

ltrUp:='wrap(c){ n:=keyTable.index(c) - 5; if(n<0)n+=25; keyTable[n%25] };

ltrAt:='wrap(r,c){ keyTable[r*5+c] };

ltrAt:='wrap(r,c){ keyTable[r*5 + c] };

text.pump(String,Void.Read, //-->digraph

'wrap(a,b){

if((ra:=row(a))==(rb:=row(b))) return(ltrLeft(a)+ltrLeft(b));

if((ra:=row(a))==(rb:=row(b))) return(ltrLeft(a) + ltrLeft(b));

if((ca:=col(a))==(cb:=col(b))) return(ltrUp(a)+ltrUp(b));

if((ca:=col(a))==(cb:=col(b))) return(ltrUp(a) + ltrUp(b));

return(ltrAt(ra,cb)+ltrAt(rb,ca));

return(ltrAt(ra,cb) + ltrAt(rb,ca));

});

})

.pump(String,Void.Read,"".create.fp(" ")).strip(); // insert blanks

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}</lang>

}

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</lang>

<lang zkl>msg:="Hide the gold in the tree stump!!!";

keyTable:=genKeyTable("playfair example");

msg.println();

e:=playfair(msg,keyTable); e.println();

decodePF(e,keyTable).println();~~</lang>~~

decodePF(e,keyTable).println();

decodePF(playfair("X",keyTable).println(),keyTable).println();

decodePF(playfair("XX",keyTable).println(),keyTable).println();</lang>

<pre>

Hide the gold in the tree stump!!!

BM OD ZB XD NA BE KU DM UI XM MO UV IF

BMNDZBXDKYBEJVDMUIXMJZZRFT

HI DE TH EG OL DI NT HE TR EX ES TU MP

HIDETHEGOLDINTHETREXSTUMPZ

MW

XZ

MW MW

XZ XZ

</pre>