Vigenere's ciphers

Algorithm is very simple. It is based on that table:
0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 
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  0
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  A  1
C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  2
D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  3
E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  4
F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  5
G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  6
H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  7
I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  8
J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  9
K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  10
L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  11
M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  12
N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  13
O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  14
P  Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  15
Q  R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  16
R  S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  17
S  T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  18
T  U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  19
U  V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  20
V  W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  21
W  X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  22
X  Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  23
Y  Z  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  24
Z  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  25
To code a text you need a keyword. Based on a letter in keyword you choose column in the table. Row is determined by the letter in text. You can read codded leter when you know column and row (keyword gives column, letter in text gives row). Next you switch to the next leter in keyword and in text. When there are no more letters in keyword you switch to the first letter.


Enter text to code:

Enter key word:



PHP code: 
<?php
	$tablica =  "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	$tablica2 = "abcdefghijklmnopqrstuvwxyz";
	$lentab = strlen($tablica);
	if(!isset($key)) $key = "keyword";
	$keylen = strlen($key);
	if(isset($text)){
		print "Original text: <font color = #00FF00><tt><b> ";
		print "$text</font></tt></B><br>";
		$textcoded = "";
		$litera = false;
		for($i = 0; $istrlen($text); $i++) {
			for($k = 0; $k <strlen($tablica); $k++)
				if($key[$i%$keylen]==$tablica[$k]||$key[$i%$keylen]==$tablica2[$k]) {
					$num = $k;
					break;
			}
			$litera = false;
			for($j = 0; $j<strlen($tablica); $j++) {
				if($tablica[$j]==$text[$i]) {
					$textcoded.=$tablica[($j+$num)%$lentab];
					$litera = true;
					break;
				}
				if($tablica2[$j]==$text[$i]) {
					$textcoded.=$tablica2[($j+$num)%$lentab];
					$litera = true;
					break;
				}
			}
			if(!$litera) $textcoded.=$text[$i];
		}
		print "Coded text:<font color = #FF0000><b><tt> $textcoded</font></tt></B><br>";
	}
	f();
?>

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