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Playfair cipher

From Rosetta Code
Playfair cipher is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Implement a Playfair cipher for encryption and decryption.

The user must be able to choose J = I or no Q in the alphabet.

The output of the encrypted and decrypted message must be in capitalized digraphs, separated by spaces.

Output example: HI DE TH EG OL DI NT HE TR EX ES TU MP.

C++[edit]

#include <iostream>
#include <string>
 
using namespace std;
 
class playfair
{
public:
void doIt( string k, string t, bool ij, bool e )
{
createGrid( k, ij ); getTextReady( t, ij, e );
if( e ) doIt( 1 ); else doIt( -1 );
display();
}
 
private:
void doIt( int dir )
{
int a, b, c, d; string ntxt;
for( string::const_iterator ti = _txt.begin(); ti != _txt.end(); ti++ )
{
if( getCharPos( *ti++, a, b ) )
if( getCharPos( *ti, c, d ) )
{
if( a == c ) { ntxt += getChar( a, b + dir ); ntxt += getChar( c, d + dir ); }
else if( b == d ){ ntxt += getChar( a + dir, b ); ntxt += getChar( c + dir, d ); }
else { ntxt += getChar( c, b ); ntxt += getChar( a, d ); }
}
}
_txt = ntxt;
}
 
void display()
{
cout << "\n\n OUTPUT:\n=========" << endl;
string::iterator si = _txt.begin(); int cnt = 0;
while( si != _txt.end() )
{
cout << *si; si++; cout << *si << " "; si++;
if( ++cnt >= 26 ) cout << endl, cnt = 0;
}
cout << endl << endl;
}
 
char getChar( int a, int b )
{
return _m[ (b + 5) % 5 ][ (a + 5) % 5 ];
}
 
bool getCharPos( char l, int &a, int &b )
{
for( int y = 0; y < 5; y++ )
for( int x = 0; x < 5; x++ )
if( _m[y][x] == l )
{ a = x; b = y; return true; }
 
return false;
}
 
void getTextReady( string t, bool ij, bool e )
{
for( string::iterator si = t.begin(); si != t.end(); si++ )
{
*si = toupper( *si ); if( *si < 65 || *si > 90 ) continue;
if( *si == 'J' && ij ) *si = 'I';
else if( *si == 'Q' && !ij ) continue;
_txt += *si;
}
if( e )
{
string ntxt = ""; size_t len = _txt.length();
for( size_t x = 0; x < len; x += 2 )
{
ntxt += _txt[x];
if( x + 1 < len )
{
if( _txt[x] == _txt[x + 1] ) ntxt += 'X';
ntxt += _txt[x + 1];
}
}
_txt = ntxt;
}
if( _txt.length() & 1 ) _txt += 'X';
}
 
void createGrid( string k, bool ij )
{
if( k.length() < 1 ) k = "KEYWORD";
k += "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; string nk = "";
for( string::iterator si = k.begin(); si != k.end(); si++ )
{
*si = toupper( *si ); if( *si < 65 || *si > 90 ) continue;
if( ( *si == 'J' && ij ) || ( *si == 'Q' && !ij ) )continue;
if( nk.find( *si ) == -1 ) nk += *si;
}
copy( nk.begin(), nk.end(), &_m[0][0] );
}
 
string _txt; char _m[5][5];
};
 
int main( int argc, char* argv[] )
{
string key, i, txt; bool ij, e;
cout << "(E)ncode or (D)ecode? "; getline( cin, i ); e = ( i[0] == 'e' || i[0] == 'E' );
cout << "Enter a en/decryption key: "; getline( cin, key );
cout << "I <-> J (Y/N): "; getline( cin, i ); ij = ( i[0] == 'y' || i[0] == 'Y' );
cout << "Enter the text: "; getline( cin, txt );
playfair pf; pf.doIt( key, txt, ij, e ); return system( "pause" );
}
Output:

(E)ncode or (D)ecode? e Enter a en/decryption key: playfair example I <-> J (Y/N): y Enter the text: Hide the gold in the tree stump

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


(E)ncode or (D)ecode? d Enter a en/decryption key: playfair example I <-> J (Y/N): y Enter the text: BMODZBXDNABEKUDMUIXMMOUVIF

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

D[edit]

Translation of: Python
import std.stdio, std.array, std.algorithm, std.range, std.ascii,
std.conv, std.string, std.regex, std.typecons;
 
string unique(in string s) pure nothrow @safe {
string result;
foreach (immutable char c; s)
if (!result.representation.canFind(c)) // Assumes ASCII string.
result ~= c;
return result;
}
 
struct Playfair {
string from, to;
string[string] enc, dec;
 
this(in string key, in string from_ = "J", in string to_ = null)
pure /*nothrow @safe*/ {
this.from = from_;
if (to_.empty)
this.to = (from_ == "J") ? "I" : "";
 
immutable m = _canonicalize(key ~ uppercase)
.unique
.chunks(5)
.map!text
.array;
auto I5 = 5.iota;
 
foreach (immutable R; m)
foreach (immutable i, immutable j; cartesianProduct(I5, I5))
if (i != j)
enc[[R[i], R[j]]] = [R[(i + 1) % 5], R[(j+1) % 5]];
 
foreach (immutable r; I5) {
immutable c = m.transversal(r).array;
foreach (immutable i, immutable j; cartesianProduct(I5, I5))
if (i != j)
enc[[c[i], c[j]]] = [c[(i + 1) % 5], c[(j+1) % 5]];
}
 
foreach (i1, j1, i2, j2; cartesianProduct(I5, I5, I5, I5))
if (i1 != i2 && j1 != j2)
enc[[m[i1][j1], m[i2][j2]]] = [m[i1][j2], m[i2][j1]];
 
dec = enc.byKeyValue.map!(t => tuple(t.value, t.key)).assocArray;
}
 
private string _canonicalize(in string s) const pure @safe {
return s.toUpper.removechars("^A-Z").replace(from, to);
}
 
string encode(in string s) const /*pure @safe*/ {
return _canonicalize(s)
.matchAll(r"(.)(?:(?!\1)(.))?")
.map!(m => enc[m[0].leftJustify(2, 'X')])
.join(' ');
}
 
string decode(in string s) const pure @safe {
return _canonicalize(s).chunks(2).map!(p => dec[p.text]).join(' ');
}
}
 
void main() [email protected]*/ {
/*immutable*/ const pf = Playfair("Playfair example");
immutable orig = "Hide the gold in...the TREESTUMP!!!";
writeln("Original: ", orig);
immutable enc = pf.encode(orig);
writeln(" Encoded: ", enc);
writeln(" Decoded: ", pf.decode(enc));
}
Output:
Original: Hide the gold in...the TREESTUMP!!!
 Encoded: BM OD ZB XD NA BE KU DM UI XM MO UV IF
 Decoded: HI DE TH EG OL DI NT HE TR EX ES TU MP

FreeBASIC[edit]

' FB 1.05.0 Win64
 
Enum PlayFairOption
noQ
iEqualsJ
End Enum
 
Dim Shared pfo As PlayFairOption '' set this before calling buildTable
Dim Shared table(1 To 5, 1 To 5) As UInteger
 
Sub buildTable(keyword As String)
Dim used(1 To 26) As Boolean '' all false by default
If pfo = noQ Then
used(17) = True
Else
used(10) = True
End If
Dim As String alphabet = UCase(keyword) + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Dim As UInteger i = 1, j = 1, k
Dim As Integer c
For k = 0 To Len(alphabet) - 1
c = alphabet[k] - 64
If c < 1 OrElse c > 26 Then Continue For
If Not used(c) Then
table(i, j) = c
used(c) = True
j += 1
If j = 6 Then
i += 1
If i = 6 Then Return '' table has been filled
j = 1
End If
End If
Next k
End Sub
 
Function getCleanText(plainText As String) As String
plainText = UCase(plainText) '' ensure everything is upper case
' get rid of any non-letters and insert X between duplicate letters
Dim As String cleanText = "", prevChar = "", nextChar
For i As UInteger = 1 To Len(plainText)
nextChar = Mid(plainText, i, 1)
' It appears that Q should be omitted altogether if noQ option is specified - we assume so anyway
If nextChar < "A" OrElse nextChar > "Z" OrElse (nextChar = "Q" AndAlso pfo = noQ) Then Continue For
' If iEqualsJ option specified, replace J with I
If nextChar = "J" AndAlso pfo = iEqualsJ Then nextChar = "I"
If nextChar <> prevChar Then
cleanText += nextChar
Else
cleanText += "X" + nextChar
End If
prevChar = nextChar
Next
If Len(cleanText) Mod 2 = 1 Then '' dangling letter at end so add another letter to complete digram
If Right(cleanText, 1) <> "X" Then
cleanText += "X"
Else
cleanText += "Z"
End If
End If
Return cleanText
End Function
 
Sub findChar(c As uInteger, ByRef row As UInteger, ByRef col As UInteger)
For i As UInteger = 1 To 5
For j As UInteger = 1 To 5
If table(i, j) = c Then
row = i
col = j
Return
End If
Next j
Next i
End Sub
 
Function encodePlayfair(plainText As String) As String
Dim As String cleanText = getCleanText(plainText)
Dim As String digram, cipherDigram, cipherText = ""
Dim As UInteger length = Len(cleanText)
Dim As UInteger char1, char2, row1, col1, row2, col2
For i As UInteger = 1 To length Step 2
digram = Mid(cleanText, i, 2)
char1 = digram[0] - 64
char2 = digram[1] - 64
findChar char1, row1, col1
findChar char2, row2, col2
If row1 = row2 Then
cipherDigram = Chr(table(row1, col1 Mod 5 + 1) + 64)
cipherDigram += Chr(table(row2, col2 Mod 5 + 1) + 64)
ElseIf col1 = col2 Then
cipherDigram = Chr(table(row1 Mod 5 + 1, col1) + 64)
cipherDigram += Chr(table(row2 Mod 5 + 1, col2) + 64)
Else
cipherDigram = Chr(table(row1, col2) + 64)
cipherDigram += Chr(table(row2, col1) + 64)
End If
cipherText += cipherDigram
If i < length Then cipherText += " "
Next i
Return cipherText
End Function
 
Function decodePlayfair(cipherText As String) As String
Dim As String digram, cipherDigram, decodedText = ""
Dim As UInteger length = Len(cipherText)
Dim As UInteger char1, char2, row1, col1, row2, col2
For i As UInteger = 1 To length Step 3 '' cipherText will include spaces so we need to skip them
cipherDigram = Mid(cipherText, i, 2)
char1 = cipherDigram[0] - 64
char2 = cipherDigram[1] - 64
findChar char1, row1, col1
findChar char2, row2, col2
If row1 = row2 Then
digram = Chr(table(row1, IIf(col1 > 1, col1 - 1, 5)) + 64)
digram += Chr(table(row2, IIf(col2 > 1, col2 - 1, 5)) + 64)
ElseIf col1 = col2 Then
digram = Chr(table(IIf(row1 > 1, row1 - 1, 5), col1) + 64)
digram += Chr(table(IIf(row2 > 1, row2 - 1, 5), col2) + 64)
Else
digram = Chr(table(row1, col2) + 64)
digram += Chr(table(row2, col1) + 64)
End If
decodedText += digram
If i < length Then decodedText += " "
Next i
Return decodedText
End Function
 
Dim As String keyword, ignoreQ, plainText, encodedText, decodedText
Line Input "Enter Playfair keyword : "; keyword
 
Do
Line Input "Ignore Q when buiding table y/n : "; ignoreQ
ignoreQ = LCase(ignoreQ)
Loop Until ignoreQ = "y" Or ignoreQ = "n"
 
pfo = IIf(ignoreQ = "y", noQ, iEqualsJ)
buildTable(keyword)
Print "The table to be used is : " : Print
For i As UInteger = 1 To 5
For j As UInteger = 1 To 5
Print Chr(table(i, j) + 64); " ";
Next j
Print
Next i
 
Print
Line Input "Enter plain text : "; plainText
Print
encodedText = encodePlayfair(plainText)
Print "Encoded text is : "; encodedText
decodedText = decodePlayFair(encodedText)
Print "Decoded text is : "; decodedText
Print
Print "Press any key to quit"
Sleep

Sample input/output:

Output:
Enter Playfair keyword : ? Playfair example
Ignore Q when buiding table  y/n : ? n
The table to be used is :

P L A Y F
I R E X M
B C D G H
K N O Q S
T U V W Z

Enter plain text : ? Hide the gold in...the TREESTUMP!!!!

Encoded text is : BM OD ZB XD NA BE KU DM UI XM MO UV IF
Decoded text is : HI DE TH EG OL DI NT HE TR EX ES TU MP

Haskell[edit]

 
import Control.Monad (guard)
import Data.Array (Array, assocs, elems, listArray, (!))
import Data.Char (toUpper)
import Data.List (nub, (\\))
import Data.List.Split (chunksOf)
import Data.Maybe (listToMaybe)
import Data.String.Utils (replace)
 
type Square a = Array (Int, Int) a
 
-- | Turns a list into an n*m-array.
array2D ::
(Int, Int) -- ^ n * m
-> [e] -> Square e
array2D maxCoord = listArray ((1, 1), maxCoord)
 
-- | Generates a playfair table starting with the specified string.
--
-- >>> makeTable "hello"
-- "HELOABCDFGIKMNPQRSTUVWXYZ"
makeTable :: String -> String
makeTable k = nub key ++ (alpha \\ key)
where
alpha = ['A' .. 'Z'] \\ "J"
key = map toUpper =<< words k
 
-- | Turns a playfair table into a 5*5 alphabet square.
makeSquare :: [a] -> Square a
makeSquare = array2D (5, 5)
 
-- | Displays a playfair square, formatted as a square.
showSquare :: Square Char -> String
showSquare d = unlines $ chunksOf 5 (elems d)
 
-- | Given a value and an association list of x-coordinate * y-coordinate * value, returns the coordinates
getIndex' :: (Eq a) => a -> [((Int, Int), a)] -> Maybe (Int, Int)
getIndex'
el = fmap fst . listToMaybe . filter ((== el) . snd)
 
encodePair, decodePair :: Eq a => Square a -> (a, a) -> Maybe (a, a)
encodePair = pairHelper (\x -> if x == 5 then 1 else x + 1)
decodePair = pairHelper (\x -> if x == 1 then 5 else x - 1)
 
pairHelper :: (Eq t)
=> (Int -> Int) -- ^ a function used for wrapping around the square
-> Square t -- ^ a playfair square
-> (t, t) -- ^ two characters
-> Maybe (t, t) -- ^ the two resulting/encoded characters
pairHelper adjust sqr (c1, c2) =
do let ps = assocs sqr
-- assigns an association list of (x-coord * y-coord) * value to ps
(x1, y1) <- getIndex' c1 ps
(x2, y2) <- getIndex'
c2 ps
-- returns the coordinates of two values in the square
-- these will later be swapped
guard $ c1 /= c2
-- the characters (and coordinates) cannot be the same
let get x = sqr ! x
-- a small utility function for extracting a value from the square
Just $
-- wrap the coordinates around and find the encrypted characters
case () of
() | y1 == y2 ->
(get (adjust x1, y1), get (adjust x2, y2))
| x1 == x2 ->
(get (x1, adjust y1), get (x2, adjust y2))
| otherwise ->
(get (x1, y2), get (x2, y1))
 
-- | Turns two characters into a tuple.
parsePair :: String -> [(Char, Char)]
parsePair = fmap (\[x, y] -> (x, y)) . words . fmap toUpper
 
-- | Turns a tuple of two characters into a string.
unparsePair :: [(Char, Char)] -> String
unparsePair = unwords . fmap (\(x, y) -> [x, y])
 
codeHelper :: (Square Char -> (Char, Char) -> Maybe (Char, Char))
-> String -> String -> Maybe String
codeHelper subs key =
fmap unparsePair .
mapM (subs (makeSquare $ makeTable key)) .
parsePair
 
playfair, unplayfair :: String -> String -> Maybe String
playfair key = codeHelper encodePair key . formatEncode
unplayfair = codeHelper decodePair
 
formatEncode :: String -> String
formatEncode =
map toUpper .
unwords .
map (\[x, y] -> if x == y then [x, 'x'] else [x, y]) .
chunksOf 2 .
replace "j" "i" .
concatMap adjustLength .
words .
filter (\n -> n `elem` (['A'..'Z'] ++ ['a'..'z']))
where
adjustLength str
| odd (length str) = str ++ "x"
| otherwise = str
 
>>> playfair "playfair example" "hide the gold in the tree stump"
Just "BM OD ZB XD NA BE KU DM UI XM KZ ZR YI"

>>> unplayfair "playfair example" "BM OD ZB XD NA BE KU DM UI XM KZ ZR YI"
Just "HI DE TH EG OL DI NT HE TR EX ST UM PX"

J[edit]

Rather than implement two versions of the rules, one for encrypt, one for decrypt, let's just make a lookup table (mapping character pairs to character pairs). To decrypt we can look up in the other direction.

Implementation:

choose=:3 :0
sel=. 'Q'e.y
alph=:(sel{'JQ')-.~a.{~65+i.26
norm=: alph restrict('I' I.@:=&'J'@]} ])`(-.&'Q')@.[email protected]
''
)
restrict=: ] -. -.~
choose 'Q'
 
setkey=:3 :0
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=: 3 :0
2{."1 -.&' '"1 ~."1 (_2]\ norm y),"1 'XQV'
)
 
encrypt=:3 :0
,alt{~ref i. pairs y
)
 
decrypt=:3 :0
,ref{~alt i. pairs y
)

Example use:

   choose 'IJ'
 
setkey 'playfair example'
encrypt 'Hide the gold in the tree stump'
BMODZBXDNABEKUDMUIXMKZZRYI
decrypt 'BMODZBXDNABEKUDMUIXMKZZRYI'
HIDETHEGOLDINTHETREXSTUMPX

Java[edit]

import java.awt.Point;
import java.util.Scanner;
 
public class PlayfairCipher {
private static char[][] charTable;
private static Point[] positions;
 
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
 
String key = prompt("Enter an encryption key (min length 6): ", sc, 6);
String txt = prompt("Enter the message: ", sc, 1);
String jti = prompt("Replace J with I? y/n: ", sc, 1);
 
boolean changeJtoI = jti.equalsIgnoreCase("y");
 
createTable(key, changeJtoI);
 
String enc = encode(prepareText(txt, changeJtoI));
 
System.out.printf("%nEncoded message: %n%s%n", enc);
System.out.printf("%nDecoded message: %n%s%n", decode(enc));
}
 
private static String prompt(String promptText, Scanner sc, int minLen) {
String s;
do {
System.out.print(promptText);
s = sc.nextLine().trim();
} while (s.length() < minLen);
return s;
}
 
private static String prepareText(String s, boolean changeJtoI) {
s = s.toUpperCase().replaceAll("[^A-Z]", "");
return changeJtoI ? s.replace("J", "I") : s.replace("Q", "");
}
 
private static void createTable(String key, boolean changeJtoI) {
charTable = new char[5][5];
positions = new Point[26];
 
String s = prepareText(key + "ABCDEFGHIJKLMNOPQRSTUVWXYZ", changeJtoI);
 
int len = s.length();
for (int i = 0, k = 0; i < len; i++) {
char c = s.charAt(i);
if (positions[c - 'A'] == null) {
charTable[k / 5][k % 5] = c;
positions[c - 'A'] = new Point(k % 5, k / 5);
k++;
}
}
}
 
private static String encode(String s) {
StringBuilder sb = new StringBuilder(s);
 
for (int i = 0; i < sb.length(); i += 2) {
 
if (i == sb.length() - 1)
sb.append(sb.length() % 2 == 1 ? 'X' : "");
 
else if (sb.charAt(i) == sb.charAt(i + 1))
sb.insert(i + 1, 'X');
}
return codec(sb, 1);
}
 
private static String decode(String s) {
return codec(new StringBuilder(s), 4);
}
 
private static String codec(StringBuilder text, int direction) {
int len = text.length();
for (int i = 0; i < len; i += 2) {
char a = text.charAt(i);
char b = text.charAt(i + 1);
 
int row1 = positions[a - 'A'].y;
int row2 = positions[b - 'A'].y;
int col1 = positions[a - 'A'].x;
int col2 = positions[b - 'A'].x;
 
if (row1 == row2) {
col1 = (col1 + direction) % 5;
col2 = (col2 + direction) % 5;
 
} else if (col1 == col2) {
row1 = (row1 + direction) % 5;
row2 = (row2 + direction) % 5;
 
} else {
int tmp = col1;
col1 = col2;
col2 = tmp;
}
 
text.setCharAt(i, charTable[row1][col1]);
text.setCharAt(i + 1, charTable[row2][col2]);
}
return text.toString();
}
}

alternative version[edit]

import java.util.Scanner;
 
public class PlayfairCipherEncryption
{
private String KeyWord = new String();
private String Key = new String();
private char matrix_arr[][] = new char[5][5];
 
public void setKey(String k)
{
String K_adjust = new String();
boolean flag = false;
K_adjust = K_adjust + k.charAt(0);
for (int i = 1; i < k.length(); i++)
{
for (int j = 0; j < K_adjust.length(); j++)
{
if (k.charAt(i) == K_adjust.charAt(j))
{
flag = true;
}
}
if (flag == false)
K_adjust = K_adjust + k.charAt(i);
flag = false;
}
KeyWord = K_adjust;
}
 
public void KeyGen()
{
boolean flag = true;
char current;
Key = KeyWord;
for (int i = 0; i < 26; i++)
{
current = (char) (i + 97);
if (current == 'j')
continue;
for (int j = 0; j < KeyWord.length(); j++)
{
if (current == KeyWord.charAt(j))
{
flag = false;
break;
}
}
if (flag)
Key = Key + current;
flag = true;
}
System.out.println(Key);
matrix();
}
 
private void matrix()
{
int counter = 0;
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 5; j++)
{
matrix_arr[i][j] = Key.charAt(counter);
System.out.print(matrix_arr[i][j] + " ");
counter++;
}
System.out.println();
}
}
 
private String format(String old_text)
{
int i = 0;
int len = 0;
String text = new String();
len = old_text.length();
for (int tmp = 0; tmp < len; tmp++)
{
if (old_text.charAt(tmp) == 'j')
{
text = text + 'i';
}
else
text = text + old_text.charAt(tmp);
}
len = text.length();
for (i = 0; i < len; i = i + 2)
{
if (text.charAt(i + 1) == text.charAt(i))
{
text = text.substring(0, i + 1) + 'x' + text.substring(i + 1);
}
}
return text;
}
 
private String[] Divid2Pairs(String new_string)
{
String Original = format(new_string);
int size = Original.length();
if (size % 2 != 0)
{
size++;
Original = Original + 'x';
}
String x[] = new String[size / 2];
int counter = 0;
for (int i = 0; i < size / 2; i++)
{
x[i] = Original.substring(counter, counter + 2);
counter = counter + 2;
}
return x;
}
 
public int[] GetDiminsions(char letter)
{
int[] key = new int[2];
if (letter == 'j')
letter = 'i';
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 5; j++)
{
if (matrix_arr[i][j] == letter)
{
key[0] = i;
key[1] = j;
break;
}
}
}
return key;
}
 
public String encryptMessage(String Source)
{
String src_arr[] = Divid2Pairs(Source);
String Code = new String();
char one;
char two;
int part1[] = new int[2];
int part2[] = new int[2];
for (int i = 0; i < src_arr.length; i++)
{
one = src_arr[i].charAt(0);
two = src_arr[i].charAt(1);
part1 = GetDiminsions(one);
part2 = GetDiminsions(two);
if (part1[0] == part2[0])
{
if (part1[1] < 4)
part1[1]++;
else
part1[1] = 0;
if (part2[1] < 4)
part2[1]++;
else
part2[1] = 0;
}
else if (part1[1] == part2[1])
{
if (part1[0] < 4)
part1[0]++;
else
part1[0] = 0;
if (part2[0] < 4)
part2[0]++;
else
part2[0] = 0;
}
else
{
int temp = part1[1];
part1[1] = part2[1];
part2[1] = temp;
}
Code = Code + matrix_arr[part1[0]][part1[1]]
+ matrix_arr[part2[0]][part2[1]];
}
return Code;
}
 
public static void main(String[] args)
{
PlayfairCipherEncryption x = new PlayfairCipherEncryption();
Scanner sc = new Scanner(System.in);
System.out.println("Enter a keyword:");
String keyword = sc.next();
x.setKey(keyword);
x.KeyGen();
System.out
.println("Enter word to encrypt: (Make sure length of message is even)");
String key_input = sc.next();
if (key_input.length() % 2 == 0)
{
System.out.println("Encryption: " + x.encryptMessage(key_input));
}
else
{
System.out.println("Message length should be even");
}
sc.close();
}
}

Kotlin[edit]

Translation of: FreeBASIC
// version 1.0.5-2
 
enum class PlayfairOption {
NO_Q,
I_EQUALS_J
}
 
class Playfair(keyword: String, val pfo: PlayfairOption) {
private val table: Array<CharArray> = Array(5, { CharArray(5) }) // 5 x 5 char array
 
init {
// build table
val used = BooleanArray(26) // all elements false
if (pfo == PlayfairOption.NO_Q)
used[16] = true // Q used
else
used[9] = true // J used
val alphabet = keyword.toUpperCase() + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
var i = 0
var j = 0
var c: Char
var d: Int
for (k in 0 until alphabet.length) {
c = alphabet[k]
if (c !in 'A'..'Z') continue
d = c.toInt() - 65
if (!used[d]) {
table[i][j] = c
used[d] = true
if (++j == 5) {
if (++i == 5) break // table has been filled
j = 0
}
}
}
}
 
private fun getCleanText(plainText: String): String {
val plainText2 = plainText.toUpperCase() // ensure everything is upper case
// get rid of any non-letters and insert X between duplicate letters
var cleanText = ""
var prevChar = '\u0000' // safe to assume null character won't be present in plainText
var nextChar: Char
for (i in 0 until plainText2.length) {
nextChar = plainText2[i]
// It appears that Q should be omitted altogether if NO_Q option is specified - we assume so anyway
if (nextChar !in 'A'..'Z' || (nextChar == 'Q' && pfo == PlayfairOption.NO_Q)) continue
// If I_EQUALS_J option specified, replace J with I
if (nextChar == 'J' && pfo == PlayfairOption.I_EQUALS_J) nextChar = 'I'
if (nextChar != prevChar)
cleanText += nextChar
else
cleanText += "X" + nextChar
prevChar = nextChar
}
val len = cleanText.length
if (len % 2 == 1) { // dangling letter at end so add another letter to complete digram
if (cleanText[len - 1] != 'X')
cleanText += 'X'
else
cleanText += 'Z'
}
return cleanText
}
 
private fun findChar(c: Char): Pair<Int, Int> {
for (i in 0..4)
for (j in 0..4)
if (table[i][j] == c) return Pair(i, j)
return Pair(-1, -1)
}
 
fun encode(plainText: String): String {
val cleanText = getCleanText(plainText)
var cipherText = ""
val length = cleanText.length
for (i in 0 until length step 2) {
val (row1, col1) = findChar(cleanText[i])
val (row2, col2) = findChar(cleanText[i + 1])
cipherText += when {
row1 == row2 -> table[row1][(col1 + 1) % 5].toString() + table[row2][(col2 + 1) % 5]
col1 == col2 -> table[(row1 + 1) % 5][col1].toString() + table[(row2 + 1) % 5][col2]
else -> table[row1][col2].toString() + table[row2][col1]
}
if (i < length - 1) cipherText += " "
}
return cipherText
}
 
fun decode(cipherText: String): String {
var decodedText = ""
val length = cipherText.length
for (i in 0 until length step 3) { // cipherText will include spaces so we need to skip them
val (row1, col1) = findChar(cipherText[i])
val (row2, col2) = findChar(cipherText[i + 1])
decodedText += when {
row1 == row2 -> table[row1][if (col1 > 0) col1 - 1 else 4].toString() + table[row2][if (col2 > 0) col2 - 1 else 4]
col1 == col2 -> table[if (row1 > 0) row1- 1 else 4][col1].toString() + table[if (row2 > 0) row2 - 1 else 4][col2]
else -> table[row1][col2].toString() + table[row2][col1]
}
if (i < length - 1) decodedText += " "
}
return decodedText
}
 
fun printTable() {
println("The table to be used is :\n")
for (i in 0..4) {
for (j in 0..4) print(table[i][j] + " ")
println()
}
}
}
 
fun main(args: Array<String>) {
print("Enter Playfair keyword : ")
val keyword: String = readLine()!!
var ignoreQ: String
do {
print("Ignore Q when buiding table y/n : ")
ignoreQ = readLine()!!.toLowerCase()
}
while (ignoreQ != "y" && ignoreQ != "n")
val pfo = if (ignoreQ == "y") PlayfairOption.NO_Q else PlayfairOption.I_EQUALS_J
val playfair = Playfair(keyword, pfo)
playfair.printTable()
print("\nEnter plain text : ")
val plainText: String = readLine()!!
val encodedText = playfair.encode(plainText)
println("\nEncoded text is : $encodedText")
val decodedText = playfair.decode(encodedText)
println("Decoded text is : $decodedText")
}
Output:
Enter Playfair keyword : Playfair example
Ignore Q when buiding table  y/n : n
The table to be used is :

P L A Y F
I R E X M
B C D G H
K N O Q S
T U V W Z

Enter plain text : Hide the gold...in the TREESTUMP!!!!

Encoded text is : BM OD ZB XD NA BE KU DM UI XM MO UV IF
Decoded text is : HI DE TH EG OL DI NT HE TR EX ES TU MP

NetRexx[edit]

/* NetRexx */
options replace format comments java crossref symbols nobinary
 
-- input arguments:
-- encipher/decipher IQ-switch key text
-- encipher/decipher -
-- a character E, D (default E; . is an alias for E)
-- IQ-switch -
-- a character I, Q (default I for I==J, Q for exclude Q; . is an alias for I)
-- key -
-- the cipher key - default plugh_xyzzy (really just PLUGHXYZ)
-- text -
-- the text to encipher/decipher
 
runSample(arg)
return
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method cipher(d_, km, digraphs) public static
if d_.upper() = 'D' then d_ = -1 -- encode or decode adjustment
else d_ = +1
cipherText = ''
loop dw = 1 to digraphs.words()
-- process the digraphs one at a time
digraph = digraphs.word(dw)
cl = ''
cr = ''
-- get each letter from the digraph
parse digraph dl +1 dr
loop r_ = 1 to km[0] while (cl cr).words() < 4
-- locate the row/col of each letter in the cipher matrix
clx = km[r_].wordpos(dl)
crx = km[r_].wordpos(dr)
if clx > 0 then cl = r_ clx
if crx > 0 then cr = r_ crx
end r_
 
-- process the digraph's rows, columns or rectangles
select
when cl.word(1) = cr.word(1) then do
-- a row
rx = cl.word(1)
clx = cl.word(2) + d_
crx = cr.word(2) + d_
if clx > 5 then clx = 1 -- wrap
if crx > 5 then crx = 1
if clx < 1 then clx = 5
if crx < 1 then crx = 5
cy = km[rx].word(clx) || km[rx].word(crx)
cipherText = cipherText cy
end
when cl.word(2) = cr.word(2) then do
-- a column
cx = cl.word(2)
rlx = cl.word(1) + d_
rrx = cr.word(1) + d_
if rlx > 5 then rlx = 1 -- wrap
if rrx > 5 then rrx = 1
if rlx < 1 then rlx = 5
if rrx < 1 then rrx = 5
cy = km[rlx].word(cx) || km[rrx].word(cx)
cipherText = cipherText cy
end
otherwise do
-- a rectangle
r1 = cl.word(1)
r2 = cr.word(1)
cy = km[r1].word(cr.word(2)) || km[r2].word(cl.word(2))
cipherText = cipherText cy
end
end
end dw
return cipherText.strip()
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method encipher(km, digraphs) public static
return cipher('E', km, digraphs)
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method decipher(km, digraphs) public static
return cipher('D', km, digraphs)
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method getDigraphs(text, IorQ, ED) private static
a2z = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
if ED.upper() \= 'D' then eks = 'X'
else eks = ''
tp = text.upper().translate('', a2z)
text = text.upper().translate(' '.copies(tp.length()), tp).space(0)
rtext = ''
ll = ''
 
loop while text \= ''
parse text lc +1 text
if ll \= lc then rtext = rtext || lc
else rtext = rtext || eks || lc
ll = lc
end
 
-- I == J or remove Q fixup
if IorQ \= 'Q' then
parse 'J I' IorQ sc .
else
sc = ''
 
rtext = rtext.changestr(IorQ, sc)
if rtext.length() // 2 \= 0 then rtext = rtext || eks
digraphs = ''
loop while rtext \= ''
parse rtext digraph +2 rtext
digraphs = digraphs digraph
end
return digraphs.space()
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method getKey(key, IorQ) private static
a2z = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
kp = (key || a2z).upper()
kr = ''
loop while kp \= ''
parse kp xx +1 kp
if \xx.datatype('u') then iterate
kr = kr xx
kp = kp.changestr(xx, '')
end
 
if IorQ = 'I' | IorQ = 'J' | IorQ = '' then
kr = kr.changestr('J', '')
else
kr = kr.changestr('Q', '')
 
return kr.space()
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method getKeyMatrix(kr) private static
km = ''
loop r_ = 1 while kr \= ''
parse kr kp +10 kr
km[0] = r_
km[r_] = kp
end r_
return km
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method runSample(arg) private static
parse arg ciph IorQ key text
if ciph = '' | ciph = '.' then ciph = 'E'
if IorQ = '' | IorQ = '.' then IorQ = 'I'
if key = '' | key = '.' then key = 'plugh_xyzzy'
if text = '' | text = '.' then text = 'NetRexx; not just a programing language for kings & queens!'
 
kr = getKey(key.space(0), IorQ)
km = getKeyMatrix(kr)
 
digraphs = getDigraphs(text, IorQ, ciph)
-- fixup for a Q in the text when Q is excluded (substitute K for Q)
if IorQ.upper = 'Q' then digraphs = digraphs.changestr('Q', 'K')
if ciph = 'E' then say text
say digraphs
if ciph.upper() = 'E' then
say encipher(km, digraphs)
else
say decipher(km, digraphs)
 
return
 
Output:
$ java -cp .:.. RPlayfairCipher00
NetRexx; not just a programing language for kings & queens!
NE TR EX XX NO TI US TA PR OG RA MI NG LA NG UA GE FO RK IN GS QU EX EN SX
TN VS CZ YY OQ WE LT VZ XP VA VX QD OU GY OU GZ UF OV PR EQ LV NH CZ NT RY

$ java -cp .:.. RPlayfairCipher00 d . . TN VS CZ YY OQ WE LT VZ XP VA VX QD OU GY OU GZ UF OV PR EQ LV NH CZ NT RY
TN VS CZ YY OQ WE LT VZ XP VA VX QD OU GY OU GZ UF OV PR EQ LV NH CZ NT RY
NE TR EX XX NO TI US TA PR OG RA MI NG LA NG UA GE FO RK IN GS QU EX EN SX

$ java -cp .:.. RPlayfairCipher00 e q playfair Hide the gold in the tree stump\!\!
Hide the gold in the tree stump!!
HI DE TH EG OL DI NT HE TR EX ES TU MP
EB IK OK GH NA IR OM JG ND JU JM MZ UI

$ java -cp .:.. RPlayfairCipher00 d q playfair EB IK OK GH NA IR OM JG ND JU JM MZ UI
EB IK OK GH NA IR OM JG ND JU JM MZ UI
HI DE TH EG OL DI NT HE TR EX ES TU MP

ooRexx[edit]

/*---------------------------------------------------------------------
* REXX program implements a PLAYFAIR cipher (encryption & decryption).
* 11.11.2013 Walter Pachl revamped, for ooRexx, the REXX program
* the logic of which was devised by Gerard Schildberger
* Invoke as rexx pf O abcd efgh ( phrase to be processed
* Defaults: 'Playfair example.'
* J
* 'Hide the gold in the tree stump'
* Major changes: avoid language elements not allowed in ooRexx
* show use of a.[expr1,expr2]
* allow key to be more than one word
* add restriction of using X or Q in text
* 12.11.2013 change order of arguments
* and comment the use of a.[expr1,expr2]
* Program should run on all Rexxes that have changestr-bif
*--------------------------------------------------------------------*/

Parse Upper Version v
oorexx=pos('OOREXX',v)>0
 
Parse Arg omit oldk '(' text
If omit='' Then omit='J'
If oldk='' Then oldk='Playfair example.'
If text='' Then text='Hide the gold in the tree stump!!'
 
newkey=scrub(oldk,1)
newtext=scrub(text)
If newtext=='' Then Call err 'TEXT is empty or has no letters'
If length(omit)\==1 Then Call err 'OMIT letter must be only one letter'
If\datatype(omit,'M') Then Call err 'OMIT letter must be a Latin alphabet letter.'
omit=translate(omit)
cant='must not contain the "OMIT" character: ' omit
If pos(omit,newtext)\==0 Then Call err 'TEXT' cant
If pos(omit,newkey)\==0 Then Call err 'cipher key' cant
abc='abcdefghijklmnopqrstuvwxyz'
abcu=translate(abc) /* uppercase alphabet */
abcx=space(translate(abcu,,omit),0) /*elide OMIT char from alphabet */
xx='X' /* char used for double characters*/
If omit==xx Then
xx='Q'
If pos(xx,newtext)>0 Then
Call err 'Sorry,' xx 'is not allowed in text'
If length(newkey)<3 Then
Call err 'cipher key is too short, must be at least 3 different letters'
abcx=space(translate(abcx,,newkey),0) /*remove any cipher characters */
grid=newkey||abcx /* only first 25 chars are used*/
Say 'old cipher key: ' strip(oldk)
padl=14+2
pad=left('',padl)
Say 'new cipher key: ' newkey
padx=left('',padl,"-")'Playfair'
Say ' omit char: ' omit /* [?] lowercase of double char. */
Say ' double char: ' xx
lxx=translate(xx,abc,abcu)
Say ' original text: ' strip(text)/* [?] doubled version of Lxx. */
Call show 'cleansed',newtext
lxxlxx=lxx||lxx
n=0 /* number of grid characters used.*/
Do row=1 For 5 /* build array of individual cells*/
Do col=1 For 5
n=n+1
a.row.col=substr(grid,n,1)
If row==1 Then
a.0.col=a.1.col
If col==5 Then Do
a.row.6=a.row.1
a.row.0=a.row.5
End
If row==5 Then Do
a.6.col=a.1.col
a.0.col=a.5.col
End
End
End
 
etext=playfair(newtext,1)
Call show 'encrypted',etext
ptext=playfair(etext,-1)
Call show 'plain',ptext
qtext=changestr(xx||xx,ptext,lxx) /*change doubled doublechar-?sing*/
qtext=changestr(lxx||xx,qtext,lxxlxx) /*change Xx --? lowercase dblChar*/
qtext=space(translate(qtext,,xx),0) /*remove char used for "doubles."*/
qtext=translate(qtext) /*reinstate the use of upperchars*/
Call show 'decoded',qtext
Say ' original text: ' newtext /* ·· and show the original text.*/
Say ''
Exit
 
playfair:
/*---------------------------------------------------------------------
* encode (e=1) or decode (e=-1) the given text (t) using the grid
*--------------------------------------------------------------------*/

Arg t,e
d=''
If e=1 Then Do
Do k=1 By 1 Until c=''
c=substr(t,k,1)
If substr(t,k+1,1)==c Then
t=left(t,k)||lxx||substr(t,k+1)
End
End
t=translate(t)
Do j=1 By 2 To length(t)
c2=strip(substr(t,j,2))
If length(c2)==1 Then
c2=c2||xx /* append X or Q char, rule 1*/
Call LR
Select
/*- This could/should be used on ooRexx -------------------------
When rowl==rowr Then c2=a.[rowl,coll+e]a.[rowr,colr+e] /*rule 2*/

When coll==colr Then c2=a.[rowl+e,coll]a.[rowr+e,colr] /*rule 3*/
*--------------------------------------------------------------*/
When rowl==rowr Then c2=aa(rowl,coll+e)aa(rowr,colr+e) /*rule 2*/
When coll==colr Then c2=aa(rowl+e,coll)aa(rowr+e,colr) /*rule 3*/
Otherwise c2=a.rowl.colr||a.rowr.coll /*rule 4*/
End
d=d||c2
End
Return d
 
aa:
/*---------------------------------------------------------------------
* ooRexx allows to use a.[rowl,coll+e]
* this function can be removed when ooRexx syntax is used to access a.
*--------------------------------------------------------------------*/

Parse Arg xrow,xcol
Return a.xrow.xcol
 
err:
/*---------------------------------------------------------------------
* Exit with an error message
*--------------------------------------------------------------------*/

Say
Say '***error!***' arg(1)
Say
Exit 13
 
lr:
/*---------------------------------------------------------------------
* get grid positions of the 2 characters
*--------------------------------------------------------------------*/

Parse Value rowcol(left(c2,1)) with rowl coll
Parse Value rowcol(right(c2,1)) with rowr colr
Return
 
rowcol: procedure Expose grid
/*---------------------------------------------------------------------
* compute row and column of the given character in the 5x5 grid
*--------------------------------------------------------------------*/

Parse Arg c
p=pos(c,grid)
col=(p-1)//5+1
row=(4+p)%5
Return row col
 
show:
/*---------------------------------------------------------------------
* Show heading and text
*--------------------------------------------------------------------*/

Arg,y
Say
Say right(arg(1) 'text: ',padl) digram(arg(2))
result=space(arg(2),0)
If arg(1)='decoded' Then Do
result=strip(result,'T',xx)
End
Say pad result
Return
 
scrub: Procedure
/*---------------------------------------------------------------------
* Remove all non-letters from the given string, uppercase letters
* and, if unique=1 remove duplicates
* 'aB + c1Bb' -> 'ABCBB' or 'ABC', respectively
*--------------------------------------------------------------------*/

Arg xxx,unique /* ARG caps all args */
d=''
used.=0
Do While xxx<>''
Parse Var xxx c +1 xxx
If datatype(c,'U') Then
If (unique=1 & pos(c,d)=0) |,
unique<>1 Then
d=d||c
End
Return d
 
digram: Procedure
/*---------------------------------------------------------------------
* Return the given string as character pairs separated by blanks
* 'ABCDEF' -> 'AB CD EF'
* 'ABCDE' -> 'AB CD E'
*--------------------------------------------------------------------*/

Parse Arg x
d=''
Do j=1 By 2 To length(x)
d=d||substr(x,j,2)' '
End
Return strip(d)

Output (sample):

old cipher key:  this is my little key
new cipher key:  THISMYLEK
     omit char:  X
   double char:  Q
 original text:  to be or not to bee

 cleansed text:  TO BE OR NO TT OB EE
                 TOBEORNOTTOBEE

encrypted text:  IJ DY JV OP MJ IJ DY OA JJ
                 IJDYJVOPMJIJDYOAJJ

    plain text:  TO BE OR NO TQ TO BE QE QQ
                 TOBEORNOTQTOBEQEQQ

  decoded text:  TO BE OR NO TT OB EE Q
                 TOBEORNOTTOBEE
 original text:  TOBEORNOTTOBEE

Perl 6[edit]

Works with: rakudo version 2016.07
# Instantiate a specific encoder/decoder.
 
sub playfair( $key,
$from = 'J',
$to = $from eq 'J' ?? 'I' !! ''
) {
 
sub canon($str) { $str.subst(/<-alpha>/,'', :g).uc.subst(/$from/,$to,:g) }
 
# Build 5x5 matrix.
my @m = canon($key ~ ('A'..'Z').join).comb.unique.map:
-> $a,$b,$c,$d,$e { [$a,$b,$c,$d,$e] }
 
# Pregenerate all forward translations.
my %ENC = gather {
# Map pairs in same row.
for @m -> @r {
for ^@r X ^@r -> (\i,\j) {
next if i == j;
take @r[i] ~ @r[j] => @r[(i+1)%5] ~ @r[(j+1)%5];
}
}
 
# Map pairs in same column.
for ^5 -> $c {
my @c = @m.map: *.[$c];
for ^@c X ^@c -> (\i,\j) {
next if i == j;
take @c[i] ~ @c[j] => @c[(i+1)%5] ~ @c[(j+1)%5];
}
}
 
# Map pairs with cross-connections.
for ^5 X ^5 X ^5 X ^5 -> (\i1,\j1,\i2,\j2) {
next if i1 == i2 or j1 == j2;
take @m[i1][j1] ~ @m[i2][j2] => @m[i1][j2] ~ @m[i2][j1];
}
}
 
# Generate reverse translations.
my %DEC = %ENC.invert;
 
return
anon sub enc($red) {
my @list = canon($red).comb(/(.) (.?) <?{ $1 ne $0 }>/);
~@list.map: { .chars == 1 ?? %ENC{$_~'X'} !! %ENC{$_} }
},
anon sub dec($black) {
my @list = canon($black).comb(/../);
~@list.map: { %DEC{$_} }
}
}
 
my (&encode,&decode) = playfair 'Playfair example';
 
my $orig = "Hide the gold in...the TREESTUMP!!!";
say " orig:\t$orig";
 
my $black = encode $orig;
say "black:\t$black";
 
my $red = decode $black;
say " red:\t$red";
Output:
 orig:	Hide the gold in...the TREESTUMP!!!
black:	BM OD ZB XD NA BE KU DM UI XM MO UV IF
  red:	HI DE TH EG OL DI NT HE TR EX ES TU MP

Python[edit]

Translation of: Perl 6
from string import ascii_uppercase
from itertools import product
from re import findall
 
def uniq(seq):
seen = {}
return [seen.setdefault(x, x) for x in seq if x not in seen]
 
def partition(seq, n):
return [seq[i : i + n] for i in xrange(0, len(seq), n)]
 
 
"""Instantiate a specific encoder/decoder."""
def playfair(key, from_ = 'J', to = None):
if to is None:
to = 'I' if from_ == 'J' else ''
 
def canonicalize(s):
return filter(str.isupper, s.upper()).replace(from_, to)
 
# Build 5x5 matrix.
m = partition(uniq(canonicalize(key + ascii_uppercase)), 5)
 
# Pregenerate all forward translations.
enc = {}
 
# Map pairs in same row.
for row in m:
for i, j in product(xrange(5), repeat=2):
if i != j:
enc[row[i] + row[j]] = row[(i + 1) % 5] + row[(j + 1) % 5]
 
# Map pairs in same column.
for c in zip(*m):
for i, j in product(xrange(5), repeat=2):
if i != j:
enc[c[i] + c[j]] = c[(i + 1) % 5] + c[(j + 1) % 5]
 
# Map pairs with cross-connections.
for i1, j1, i2, j2 in product(xrange(5), repeat=4):
if i1 != i2 and j1 != j2:
enc[m[i1][j1] + m[i2][j2]] = m[i1][j2] + m[i2][j1]
 
# Generate reverse translations.
dec = dict((v, k) for k, v in enc.iteritems())
 
def sub_enc(txt):
lst = findall(r"(.)(?:(?!\1)(.))?", canonicalize(txt))
return " ".join(enc[a + (b if b else 'X')] for a, b in lst)
 
def sub_dec(encoded):
return " ".join(dec[p] for p in partition(canonicalize(encoded), 2))
 
return sub_enc, sub_dec
 
 
(encode, decode) = playfair("Playfair example")
orig = "Hide the gold in...the TREESTUMP!!!"
print "Original:", orig
enc = encode(orig)
print "Encoded:", enc
print "Decoded:", decode(enc)
Output:
Original: Hide the gold in...the TREESTUMP!!!
Encoded: BM OD ZB XD NA BE KU DM UI XM MO UV IF
Decoded: HI DE TH EG OL DI NT HE TR EX ES TU MP

REXX[edit]

Quite a bit of the REXX code deals with error checking, accepting arguments, and displaying the options used, and displaying input and output.
For ease of viewing and comparing, the output is in capitalized digraphs (which are really digrams) as well as the original input(s).
Thanks to Walter Pachl, this program is now sensitive of using a suitable double character when   X   is present in the cipher key.
Also, more thanks are due to Walter Pachl for finding that the cipher key can't contain the OMIT character.
A fair amount of code was added to massage the decrypted encryption to remove doubled   Xes   so as to match the original text
(this is the possible text part of the REXX code).

/*REXX program implements a  PLAYFAIR cipher  (encryption & decryption).*/
@abc='abcdefghijklmnopqrstuvwxyz'; @[email protected] /*lower and upper ABC's.*/
parse arg omit key '(' text /*TEXT is the phrase to be used. */  ;oldK=key /*save old.*/
if key =='' | key ==',' then do; key='Playfair example.'; oldK=key " ◄───using the default."; end
if omit=='' | omit==',' then omit='J' /*the "omitted" character. */
if text='' then text='Hide the gold in the tree stump!!' /*default.*/
newKey =scrub(key , 1) /*scrub old cipher key──► newKey */
newText=scrub(text ) /* " " text ──► newText*/
if newText=='' then call err 'TEXT is empty or has no letters'
if length(omit)\==1 then call err 'OMIT letter must be only one letter'
if \datatype(omit,'M') then call err 'OMIT letter must be a Latin alphabet letter.'
upper omit @abcU /*uppercase OMIT char & alphabet.*/
cant='can''t contain the "OMIT" character: ' omit
if pos(omit,newText)\==0 then call err 'TEXT' cant
if pos(omit,newKey) \==0 then call err 'cipher key' cant
fill=space(translate(@abcU,, omit), 0) /*elide OMIT char from alphabet. */
xx='X'; if omit==xx then xx='Q' /*char used for double characters*/
if length(newKey)<3 then call err 'cipher key is too short, must be ≥3 unique characters.'
fill=space(translate(fill,,newKey),0) /*remove any cipher characters. */
grid=newKey || fill /*only first 25 chars are used.*/
say 'old cipher key: ' strip(oldK)  ; padL=14+2; pad=left('',padL)
say 'new cipher key: ' newKey  ; padX=left('',padL,"═")'Playfair'
say ' omit char: ' omit /* [↓] lowercase of double char.*/
say ' double char: ' xx  ; Lxx=translate(xx, @abc, @abcU)
say ' original text: ' strip(text) /* [↓] doubled version of Lxx. */
call show 'cleansed', newText  ; LxxLxx=Lxx || Lxx
#=0 /*number of grid characters used.*/
do row =1 for 5 /*build array of individual cells*/
do col=1 for 5; #=#+1; @.row.col=substr(grid,#,1)
if row==1 then @.0.col=@.1.col
if col==5 then do; @.row.6=@.row.1; @.row.0=@.row.5; end
if row==5 then do; @.6.col=@.1.col; @.0.col=@.5.col; end
end /*col*/
end /*row*/
 
eText=.Playfair(newText, 1); call show 'encrypted' , eText
pText=.Playfair(eText ); call show 'plain' , pText
qText=changestr(xx ||xx,pText,Lxx) /*change doubled doublechar─►sing*/
qText=changestr(Lxx||xx,qText,LxxLxx) /*change Xx ──► lowercase dblChar*/
qText=space(translate(qText,,xx),0) /*remove char used for "doubles."*/
upper qText /*reinstate the use of upperchars*/
if length(qText)\==length(pText) then call show 'possible', qText
say ' original text: ' newText; say /*··· and show the original text.*/
if qtext==newText then say padx 'encryption──► decryption──► encryption worked.'
exit /*stick a fork in it, we're done.*/
/*──────────────────────────────────one─line subroutines───────────────────────────────*/
@@: parse arg Xrow,Xcol; return @.Xrow.Xcol
err: say; say '***error!***' arg(1); say; exit 13
LR: rowL=row(left(__,1)); colL=_; rowR=row(right(__,1)); colR=_; return length(__)
row:  ?=pos(arg(1),grid); _=(?-1)//5+1; return (4+?)%5
show: arg ,y; say; say right(arg(1) 'text: ',padL) digram(y); say pad space(y,0); return
/*──────────────────────────────────SCRUB subroutine────────────────────*/
scrub: procedure; arg xxx,unique; xxx=space(xxx,0) /*ARG caps all args*/
$=; do j=1 for length(xxx); _=substr(xxx,j,1)
if unique==1 then if pos(_,$)\==0 then iterate /*unique?*/
if datatype(_,'M') then $=$||_ /*only use Latin letters. */
end /*j*/
return $
/*──────────────────────────────────DIGRAM subroutine───────────────────*/
digram: procedure; parse arg x; $=; do j=1 by 2 to length(x)
$=$ || substr(x,j,2)' '
end /*j*/
return strip($)
/*──────────────────────────────────.PLAYFAIR subroutine────────────────*/
.Playfair: arg T,encrypt; i=-1; if encrypt==1 then i=1; $=
do k=1 while i==1; _=substr(T,k,1); if _==' ' then leave
if _==substr(T,k+1 ,1) then T=left(T,k) || Lxx || substr(T,k+1)
end /*k*/
upper T
do j=1 by 2 to length(T); __=strip(substr(T,j,2))
if LR()==1 then __=__ || xx; call LR /*append X or Q char, rule 1*/
select
when rowL==rowR then __=@@(rowL, colL+i)@@(rowR, colR+i) /*rule 2*/
when colL==colR then __=@@(rowL+i,colL )@@(rowR+i,colR) /*rule 3*/
otherwise __=@@(rowL, colR )@@(rowR, colL) /*rule 4*/
end /*select*/
$=$ || __
end /*j*/
return $

Some older REXXes don't have a changestr bif, so one is included here ──► CHANGESTR.REX.

output when using the default inputs:

old cipher key:  Playfair example.    ◄───using the default.
new cipher key:  PLAYFIREXM
     omit char:  J
   double char:  X
 original text:  Hide the gold in the tree stump!!

 cleansed text:  HI DE TH EG OL DI NT HE TR EE ST UM P
                 HIDETHEGOLDINTHETREESTUMP

encrypted text:  BM OD ZB XD NA BE KU DM UI XM MO UV IF
                 BMODZBXDNABEKUDMUIXMMOUVIF

    plain text:  HI DE TH EG OL DI NT HE TR EX ES TU MP
                 HIDETHEGOLDINTHETREXESTUMP

 possible text:  HI DE TH EG OL DI NT HE TR EE ST UM P
                 HIDETHEGOLDINTHETREESTUMP
 original text:  HIDETHEGOLDINTHETREESTUMP

════════════════Playfair encryption──► decryption──► encryption worked. 

output when using the input of:   x stuvw (myteest

old cipher key:  stuvw
new cipher key:  STUVW
     omit char:  X
   double char:  Q
 original text:  myteest

 cleansed text:  MY TE ES T
                 MYTEEST

encrypted text:  NR WB ZB TU
                 NRWBZBTU

    plain text:  MY TE QE ST
                 MYTEQEST

 possible text:  MY TE ES T
                 MYTEEST
 original text:  MYTEEST

════════════════Playfair encryption──► decryption──► encryption worked.

SQL[edit]

 
--Clean up previous run
IF EXISTS (SELECT *
FROM SYS.TYPES
WHERE NAME = 'FairPlayTable')
DROP TYPE FAIRPLAYTABLE
 
--Set Types
CREATE TYPE FAIRPLAYTABLE AS TABLE (LETTER VARCHAR(1), COLID INT, ROWID INT)
 
GO
 
--Configuration Variables
DECLARE @KEYWORD VARCHAR(25) = 'CHARLES' --Keyword for encryption
DECLARE @INPUT VARCHAR(MAX) = 'Testing Seeconqz' --Word to be encrypted
DECLARE @Q INT = 0 -- Q removed?
DECLARE @ENCRYPT INT = 1 --Encrypt?
--Setup Variables
DECLARE @WORDS TABLE
(
WORD_PRE VARCHAR(2),
WORD_POST VARCHAR(2)
)
DECLARE @T_TABLE FAIRPLAYTABLE
DECLARE @NEXTLETTER CHAR(1)
DECLARE @WORD VARCHAR(2),
@COL1 INT,
@COL2 INT,
@ROW1 INT,
@ROW2 INT,
@TMP INT
DECLARE @SQL NVARCHAR(MAX) = '',
@COUNTER INT = 1,
@I INT = 1
DECLARE @COUNTER_2 INT = 1
 
SET @INPUT = REPLACE(@INPUT, ' ', '')
SET @KEYWORD = UPPER(@KEYWORD)
 
DECLARE @USEDLETTERS VARCHAR(MAX) = ''
DECLARE @TESTWORDS VARCHAR(2),
@A INT = 0
 
WHILE @COUNTER_2 <= 5
BEGIN
WHILE @COUNTER <= 5
BEGIN
IF LEN(@KEYWORD) > 0
BEGIN
SET @NEXTLETTER = LEFT(@KEYWORD, 1)
SET @KEYWORD = RIGHT(@KEYWORD, LEN(@KEYWORD) - 1)
 
IF CHARINDEX(@NEXTLETTER, @USEDLETTERS) = 0
BEGIN
INSERT INTO @T_TABLE
SELECT @NEXTLETTER,
@COUNTER,
@COUNTER_2
 
SET @COUNTER = @COUNTER + 1
SET @USEDLETTERS = @USEDLETTERS + @NEXTLETTER
END
END
ELSE
BEGIN
WHILE 1 = 1
BEGIN
IF CHARINDEX(CHAR(64 + @I), @USEDLETTERS) = 0
AND NOT ( CHAR(64 + @I) = 'Q'
AND @Q = 1 )
AND NOT ( @Q = 0
AND CHAR(64 + @I) = 'J' )
BEGIN
SET @NEXTLETTER = CHAR(64 + @I)
SET @USEDLETTERS = @USEDLETTERS + CHAR(64 + @I)
SET @I = @I + 1
 
BREAK
END
 
SET @I = @I + 1
END
 
-- SELECT 1 AS [T]
--BREAK
INSERT INTO @T_TABLE
SELECT @NEXTLETTER,
@COUNTER,
@COUNTER_2
 
SET @COUNTER = @COUNTER + 1
END
END
 
SET @COUNTER_2 = @COUNTER_2 + 1
SET @COUNTER = 1
END
 
--Split word into Digraphs
WHILE @A < 1
BEGIN
SET @TESTWORDS = UPPER(LEFT(@INPUT, 2))
 
IF LEN(@TESTWORDS) = 1
BEGIN
SET @TESTWORDS = @TESTWORDS + 'X'
SET @A = 1
END
ELSE IF RIGHT(@TESTWORDS, 1) = LEFT(@TESTWORDS, 1)
BEGIN
SET @TESTWORDS = RIGHT(@TESTWORDS, 1) + 'X'
SET @INPUT = RIGHT(@INPUT, LEN(@INPUT) - 1)
END
ELSE
SET @INPUT = RIGHT(@INPUT, LEN(@INPUT) - 2)
 
IF LEN(@INPUT) = 0
SET @A = 1
 
INSERT @WORDS
SELECT @TESTWORDS,
''
END
 
--Start Encryption
IF @ENCRYPT = 1
BEGIN
--Loop through Digraphs amd encrypt
DECLARE WORDS_LOOP CURSOR LOCAL FORWARD_ONLY FOR
SELECT WORD_PRE
FROM @WORDS
FOR UPDATE OF WORD_POST
 
OPEN WORDS_LOOP
 
FETCH NEXT FROM WORDS_LOOP INTO @WORD
 
WHILE @@FETCH_STATUS = 0
BEGIN
--Find letter positions
SET @ROW1 = (SELECT ROWID
FROM @T_TABLE
WHERE LETTER = LEFT(@WORD, 1))
SET @ROW2 = (SELECT ROWID
FROM @T_TABLE
WHERE LETTER = RIGHT(@WORD, 1))
SET @COL1 = (SELECT COLID
FROM @T_TABLE
WHERE LETTER = LEFT(@WORD, 1))
SET @COL2 = (SELECT COLID
FROM @T_TABLE
WHERE LETTER = RIGHT(@WORD, 1))
 
--Move positions according to encryption rules
IF @COL1 = @COL2
BEGIN
SET @ROW1 = @ROW1 + 1
SET @ROW2 = @ROW2 + 1
--select 'row'
END
ELSE IF @ROW1 = @ROW2
BEGIN
SET @COL1 = @COL1 + 1
SET @COL2 = @COL2 + 1
--select 'col'
END
ELSE
BEGIN
SET @TMP = @COL2
SET @COL2 = @COL1
SET @COL1 = @TMP
--select 'reg'
END
 
IF @ROW1 = 6
SET @ROW1 = 1
 
IF @ROW2 = 6
SET @ROW2 = 1
 
IF @COL1 = 6
SET @COL1 = 1
 
IF @COL2 = 6
SET @COL2 = 1
 
--Find encrypted letters by positions
UPDATE @WORDS
SET WORD_POST = (SELECT (SELECT LETTER
FROM @T_TABLE
WHERE ROWID = @ROW1
AND COLID = @COL1)
+ (SELECT LETTER
FROM @T_TABLE
WHERE COLID = @COL2
AND ROWID = @ROW2))
WHERE WORD_PRE = @WORD
 
FETCH NEXT FROM WORDS_LOOP INTO @WORD
END
 
CLOSE WORDS_LOOP
 
DEALLOCATE WORDS_LOOP
END
--Start Decryption
ELSE
BEGIN
--Loop through Digraphs amd decrypt
DECLARE WORDS_LOOP CURSOR LOCAL FORWARD_ONLY FOR
SELECT WORD_PRE
FROM @WORDS
FOR UPDATE OF WORD_POST
 
OPEN WORDS_LOOP
 
FETCH NEXT FROM WORDS_LOOP INTO @WORD
 
WHILE @@FETCH_STATUS = 0
BEGIN
--Find letter positions
SET @ROW1 = (SELECT ROWID
FROM @T_TABLE
WHERE LETTER = LEFT(@WORD, 1))
SET @ROW2 = (SELECT ROWID
FROM @T_TABLE
WHERE LETTER = RIGHT(@WORD, 1))
SET @COL1 = (SELECT COLID
FROM @T_TABLE
WHERE LETTER = LEFT(@WORD, 1))
SET @COL2 = (SELECT COLID
FROM @T_TABLE
WHERE LETTER = RIGHT(@WORD, 1))
 
--Move positions according to encryption rules
IF @COL1 = @COL2
BEGIN
SET @ROW1 = @ROW1 - 1
SET @ROW2 = @ROW2 - 1
--select 'row'
END
ELSE IF @ROW1 = @ROW2
BEGIN
SET @COL1 = @COL1 - 1
SET @COL2 = @COL2 - 1
--select 'col'
END
ELSE
BEGIN
SET @TMP = @COL2
SET @COL2 = @COL1
SET @COL1 = @TMP
--select 'reg'
END
 
IF @ROW1 = 0
SET @ROW1 = 5
 
IF @ROW2 = 0
SET @ROW2 = 5
 
IF @COL1 = 0
SET @COL1 = 5
 
IF @COL2 = 0
SET @COL2 = 5
 
--Find decrypted letters by positions
UPDATE @WORDS
SET WORD_POST = (SELECT (SELECT LETTER
FROM @T_TABLE
WHERE ROWID = @ROW1
AND COLID = @COL1)
+ (SELECT LETTER
FROM @T_TABLE
WHERE COLID = @COL2
AND ROWID = @ROW2))
WHERE WORD_PRE = @WORD
 
FETCH NEXT FROM WORDS_LOOP INTO @WORD
END
 
CLOSE WORDS_LOOP
 
DEALLOCATE WORDS_LOOP
END
 
--Output
DECLARE WORDS CURSOR LOCAL FAST_FORWARD FOR
SELECT WORD_POST
FROM @WORDS
 
OPEN WORDS
 
FETCH NEXT FROM WORDS INTO @WORD
 
WHILE @@FETCH_STATUS = 0
BEGIN
SET @SQL = @SQL + @WORD + ' '
 
FETCH NEXT FROM WORDS INTO @WORD
END
 
CLOSE WORDS
 
DEALLOCATE WORDS
 
SELECT @SQL
 
--Cleanup
IF EXISTS (SELECT *
FROM SYS.TYPES
WHERE NAME = 'FairPlayTable')
DROP TYPE FAIRPLAYTABLE
 

Tcl[edit]

Works with: Tcl version 8.6
package require TclOO
 
oo::class create Playfair {
variable grid lookup excluder
constructor {{keyword "PLAYFAIR EXAMPLE"} {exclude "J"}} {
# Tweaking according to exact operation mode
if {$exclude eq "J"} {
set excluder "J I"
} else {
set excluder [list $exclude ""]
}
 
# Clean up the keyword source
set keys [my Clean [append keyword "ABCDEFGHIJKLMNOPQRSTUVWXYZ"]]
 
# Generate the encoding grid
set grid [lrepeat 5 [lrepeat 5 ""]]
set idx -1
for {set i 0} {$i < 5} {incr i} {for {set j 0} {$j < 5} {} {
if {![info exist lookup([set c [lindex $keys [incr idx]]])]} {
lset grid $i $j $c
set lookup($c) [list $i $j]
incr j
}
}}
 
# Sanity check
if {[array size lookup] != 25} {
error "failed to build encoding table correctly"
}
}
 
# Worker to apply a consistent cleanup/split rule
method Clean {str} {
set str [string map $excluder [string toupper $str]]
split [regsub -all {[^A-Z]} $str ""] ""
}
 
# These public methods are implemented by a single non-public method
forward encode my Transform 1
forward decode my Transform -1
 
# The application of the Playfair cypher transform
method Transform {direction message} {
# Split message into true digraphs
foreach c [my Clean $message] {
if {![info exists lookup($c)]} continue
if {[info exist c0]} {
lappend digraphs $c0 [expr {$c0 eq $c ? "X" : $c}]
unset c0
} else {
set c0 $c
}
}
if {[info exist c0]} {
lappend digraphs $c0 "Z"
}
 
# Encode the digraphs
set result ""
foreach {a b} $digraphs {
lassign $lookup($a) ai aj
lassign $lookup($b) bi bj
if {$ai == $bi} {
set aj [expr {($aj + $direction) % 5}]
set bj [expr {($bj + $direction) % 5}]
} elseif {$aj == $bj} {
set ai [expr {($ai + $direction) % 5}]
set bi [expr {($bi + $direction) % 5}]
} else {
set tmp $aj
set aj $bj
set bj $tmp
}
lappend result [lindex $grid $ai $aj][lindex $grid $bi $bj]
}
 
# Real use would be: return [join $result ""]
return $result
}
}

Demonstrating:

Playfair create cypher "Playfair Example"
set plaintext "Hide the gold in...the TREESTUMP!!!"
set encoded [cypher encode $plaintext]
set decoded [cypher decode $encoded]
puts "Original: $plaintext"
puts "Encoded: $encoded"
puts "Decoded: $decoded"
Output:
Original: Hide the gold in...the TREESTUMP!!!
Encoded:  BM OD ZB XD NA BE KU DM UI XM KZ ZR FT
Decoded:  HI DE TH EG OL DI NT HE TR EX ST UM PZ

zkl[edit]

fcn genKeyTable(key,deadChr){ // deadChr=="Q" or "J"
deadChr=deadChr.toUpper();
key=key.toUpper().unique() - " " - deadChr;
return(key + (["A".."Z"].pump(String) - deadChr - key), deadChr);
}
fcn playfair(text,keytable){  // text is a-z only
keyTable,deadChr:=keytable;
text=text.toUpper();
text-=text - keyTable; // remove unencodable characters
if(deadChr=="Q") text-=deadChr; else text=text.replace("J","I");
 
text=text.pump(String,T(Void.Read,1,False),
fcn(a,b=""){ if(a==b) a+"X"+b else a+b });
if(text.len().isOdd) text+="Z";
 
row:='wrap(c){ keyTable.index(c)/5 };
col:='wrap(c){ keyTable.index(c)%5 };
ltrRight:='wrap(c){ keyTable[(keyTable.index(c) + 1)%25] };
ltrBelow:='wrap(c){ keyTable[(keyTable.index(c) + 5)%25] };
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(ltrRight(a) + ltrRight(b));
if((ca:=col(a))==(cb:=col(b))) return(ltrBelow(a) + ltrBelow(b));
return(ltrAt(ra,cb) + ltrAt(rb,ca));
})
.pump(String,Void.Read,"".create.fp(" ")).strip(); // insert blanks
}
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] };
ltrUp:='wrap(c){ n:=keyTable.index(c) - 5; if(n<0)n+=25; keyTable[n%25] };
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((ca:=col(a))==(cb:=col(b))) return(ltrUp(a) + ltrUp(b));
return(ltrAt(ra,cb) + ltrAt(rb,ca));
})
.pump(String,Void.Read,"".create.fp(" ")).strip(); // insert blanks
}
 
msg:="Hide the gold in the tree stump!!!";
keyTable:=genKeyTable("playfair example");
msg.println();
e:=playfair(msg,keyTable); e.println();
decodePF(e,keyTable).println();
playfair("XX",keyTable).println() : decodePF(_,keyTable).println();
Output:
Hide the gold in the tree stump!!!
BM OD ZB XD NA BE KU DM UI XM MO UV IF
HI DE TH EG OL DI NT HE TR EX ES TU MP
MM MW
XX XZ