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I need help in Encrypt & Decrypt Scripts

Discussion in 'PHP' started by yak, Aug 21, 2005.

  1. #1
    I got a encrypt script like this:

    <?php
    function changedatain($plain_data,$key){
    
       // encode plain data with key using xoft encryption
       
       $key_length=0; //key length counter 
       $all_bin_chars="";
       $cipher_data="";
    
       for($i=0;$i<strlen($plain_data);$i++){
    $p=substr($plain_data,$i,1);   // p = plaintext
    $k=substr($key,$key_length,1); // k = key
    $key_length++;
    
    if($key_length>=strlen($key)){
    $key_length=0;
    }
    
    $dec_chars=ord($p)^ord($k);
    $dec_chars=$dec_chars + strlen($key);
    $bin_chars=decbin($dec_chars);
    
    while(strlen($bin_chars)<8){
    $bin_chars="0".$bin_chars;
    }
    
    $all_bin_chars=$all_bin_chars.$bin_chars;
    
       }
    
       $m=0;
    
       for($j=0;$j<strlen($all_bin_chars);$j=$j+4){
    $four_bit=substr($all_bin_chars,$j,4);     // split 8 bit to 4 bit
    $four_bit_dec=bindec($four_bit);
    
    $decimal_value=$four_bit_dec * 4 + $m;     //multiply by 4 plus m where m=0,1,2, or 3
    
    $base64_value=dectobase64($decimal_value); //convert to base64 value
    $cipher_data=$cipher_data.$base64_value;
    $m++;
    
    if($m>3){
    $m=0;
    }
       }
       
       return $cipher_data;
    }
    
    function dectobase64($decimal_value){
    
       // convert decimal value into base64 value 
    
       switch($decimal_value){
    case 0: $base64_value="A";break;
    case 1: $base64_value="B";break;
    case 2: $base64_value="C";break;
    case 3: $base64_value="D";break;
    case 4: $base64_value="E";break;
    case 5: $base64_value="F";break;
    case 6: $base64_value="G";break;
    case 7: $base64_value="H";break;
    case 8: $base64_value="I";break;
    case 9: $base64_value="J";break;
    case 10: $base64_value="K";break;
    case 11: $base64_value="L";break;
    case 12: $base64_value="M";break;
    case 13: $base64_value="N";break;
    case 14: $base64_value="O";break;
    case 15: $base64_value="P";break;
    case 16: $base64_value="Q";break;
    case 17: $base64_value="R";break;
    case 18: $base64_value="S";break;
    case 19: $base64_value="T";break;
    case 20: $base64_value="U";break;
    case 21: $base64_value="V";break;
    case 22: $base64_value="W";break;
    case 23: $base64_value="X";break;
    case 24: $base64_value="Y";break;
    case 25: $base64_value="Z";break;
    case 26: $base64_value="a";break;
    case 27: $base64_value="b";break;
    case 28: $base64_value="c";break;
    case 29: $base64_value="d";break;
    case 30: $base64_value="e";break;
    case 31: $base64_value="f";break;
    case 32: $base64_value="g";break;
    case 33: $base64_value="h";break;
    case 34: $base64_value="i";break;
    case 35: $base64_value="j";break;
    case 36: $base64_value="k";break;
    case 37: $base64_value="l";break;
    case 38: $base64_value="m";break;
    case 39: $base64_value="n";break;
    case 40: $base64_value="o";break;
    case 41: $base64_value="p";break;
    case 42: $base64_value="q";break;
    case 43: $base64_value="r";break;
    case 44: $base64_value="s";break;
    case 45: $base64_value="t";break;
    case 46: $base64_value="u";break;
    case 47: $base64_value="v";break;
    case 48: $base64_value="w";break;
    case 49: $base64_value="x";break;
    case 50: $base64_value="y";break;
    case 51: $base64_value="z";break;
    case 52: $base64_value="0";break;
    case 53: $base64_value="1";break;
    case 54: $base64_value="2";break;
    case 55: $base64_value="3";break;
    case 56: $base64_value="4";break;
    case 57: $base64_value="5";break;
    case 58: $base64_value="6";break;
    case 59: $base64_value="7";break;
    case 60: $base64_value="8";break;
    case 61: $base64_value="9";break;
    case 62: $base64_value="+";break;
    case 63: $base64_value="/";break;
    case 64: $base64_value="=";break;
    default: $base64_value="a";break;
       }
       
       return $base64_value;
    }
    ?>
    Code (markup):

    I asked my friend and he gave me this decrypt script:
    SEMrush
    <?php
    function changedataout($cipher_data,$key){
    
       // decode cipher data with key using xoft encryption */
    
       $m=0;
       $all_bin_chars="";
    
       for($i=0;$i<strlen($cipher_data);$i++){
    $c=substr($cipher_data,$i,1);             // c = ciphertext
    $decimal_value=base64todec($c);           //convert to decimal value
    
    $decimal_value=($decimal_value - $m) / 4; //substract by m where m=0,1,2,or 3 then divide by 4
    
    $four_bit=decbin($decimal_value);
    
    while(strlen($four_bit)<4){
    $four_bit="0".$four_bit;
    }
    
    $all_bin_chars=$all_bin_chars.$four_bit;
    $m++;
    
    if($m>3){
    $m=0;
    }
       }
    
       $key_length=0;
       $plain_data="";
    
       for($j=0;$j<strlen($all_bin_chars);$j=$j+8){
    $c=substr($all_bin_chars,$j,8);
    $k=substr($key,$key_length,1);
    
    $dec_chars=bindec($c);
    $dec_chars=$dec_chars - strlen($key);
    $c=chr($dec_chars);
    $key_length++;
    
    if($key_length>=strlen($key)){
    $key_length=0;
    }
    
    $dec_chars=ord($c)^ord($k);
    $p=chr($dec_chars);
    $plain_data=$plain_data.$p;
       }
       
       return $plain_data;
    }
    
    function base64todec($base64_value){
    
       // convert base64 value into decimal value
    
       switch($base64_value){
    case "A":$decimal_value=0;break;
    case "B":$decimal_value=1;break;
    case "C":$decimal_value=2;break;
    case "D":$decimal_value=3;break;
    case "E":$decimal_value=4;break;
    case "F":$decimal_value=5;break;
    case "G":$decimal_value=6;break;
    case "H":$decimal_value=7;break;
    case "I":$decimal_value=8;break;
    case "J":$decimal_value=9;break;
    case "K":$decimal_value=10;break;
    case "L":$decimal_value=11;break;
    case "M":$decimal_value=12;break;
    case "N":$decimal_value=13;break;
    case "O":$decimal_value=14;break;
    case "P":$decimal_value=15;break;
    case "Q":$decimal_value=16;break;
    case "R":$decimal_value=17;break;
    case "S":$decimal_value=18;break;
    case "T":$decimal_value=19;break;
    case "U":$decimal_value=20;break;
    case "V":$decimal_value=21;break;
    case "W":$decimal_value=22;break;
    case "X":$decimal_value=23;break;
    case "Y":$decimal_value=24;break;
    case "Z":$decimal_value=25;break;
    case "a":$decimal_value=26;break;
    case "b":$decimal_value=27;break;
    case "c":$decimal_value=28;break;
    case "d":$decimal_value=29;break;
    case "e":$decimal_value=30;break;
    case "f":$decimal_value=31;break;
    case "g":$decimal_value=32;break;
    case "h":$decimal_value=33;break;
    case "i":$decimal_value=34;break;
    case "j":$decimal_value=35;break;
    case "k":$decimal_value=36;break;
    case "l":$decimal_value=37;break;
    case "m":$decimal_value=38;break;
    case "n":$decimal_value=39;break;
    case "o":$decimal_value=40;break;
    case "p":$decimal_value=41;break;
    case "q":$decimal_value=42;break;
    case "r":$decimal_value=43;break;
    case "s":$decimal_value=44;break;
    case "t":$decimal_value=45;break;
    case "u":$decimal_value=46;break;
    case "v":$decimal_value=47;break;
    case "w":$decimal_value=48;break;
    case "x":$decimal_value=49;break;
    case "y":$decimal_value=50;break;
    case "z":$decimal_value=51;break;
    case "0":$decimal_value=52;break;
    case "1":$decimal_value=53;break;
    case "2":$decimal_value=54;break;
    case "3":$decimal_value=55;break;
    case "4":$decimal_value=56;break;
    case "5":$decimal_value=57;break;
    case "6":$decimal_value=58;break;
    case "7":$decimal_value=59;break;
    case "8":$decimal_value=60;break;
    case "9":$decimal_value=61;break;
    case "+":$decimal_value=62;break;
    case "/":$decimal_value=63;break;
    case "=":$decimal_value=64;break;
    default: $decimal_value=0;break;
       }
       
       return $decimal_value;
    }
    ?>
    Code (markup):

    But I don't know how to code a HTML Page with this decrypt script so that I can put the encrypted word in it and decrypted it. Would you please help me to code it? Thank you very much.
     
    yak, Aug 21, 2005 IP
    SEMrush
  2. J.D.

    J.D. Peon

    Messages:
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    #2
    Home-grown encryption schemes like this will cost you your data one day. Use standard encryption mechanisms instead:

    http://www.php.net/manual/en/ref.mcrypt.php

    Also, when possible, don't encrypt values you return to the client (page HTML, cookies, etc) - use hashes instead. It is easier to break encrypted strings than hashes.

    J.D.
     
    J.D., Aug 21, 2005 IP