Latihan Kriptografi Algoritma Shift Cipher PHP

<?php

echo “Latihan kriptografi | Algoritma Sfhit Chiper”;

echo “<br/>”;

echo “plaintext = PINTU”;

echo “<br/>”;

echo “Enkripsitext = “.enkripsi(“PINTU”);

function enkripsi ($text){

  $plaintext = str_split($text);

  $enkripsitext = “”;

  $enkripsikey = 5;

  foreach ($plaintext as $key => $value) {

    $enkripsitext .= (subtitusi($value) +$enkripsikey).”,”;

  }

  $hasil = rtrim($enkripsitext,”,”);

  $enkripsiplain = explode(“,”, $hasil);

  $enkripsihasil = “”;

  foreach ($enkripsiplain as $key => $value) {

    $enkripsihasil .= desubtitusi($value).”,”;

  }

  $result = rtrim($enkripsihasil,”,”);

  echo “hasil awal adalah $hasil dan akhir adalah”;

  return $result;

}

function dekripsi ($text){

}

function desubtitusi ($text){

  $alphabet = [

    0 => “A”,

    1 => “B”,

    2 => “C”,

    3 => “D”,

    4 => “E”,

    5 => “F”,

    6 => “G”,

    7 => “H”,

    8 => “I”,

    9 => “J”,

    10 => “K”,

    11 => “L”,

    12 => “M”,

    13 => “N”,

    14 => “O”,

    15 => “P”,

    16 => “Q”,

    17 => “R”,

    18 => “S”,

    19 => “T”,

    20 => “U”,

    21 => “V”,

    22 => “W”,

    23 => “X”,

    24 => “Y”,

    25 => “Z”,

  ];

  return $alphabet [strtoupper($text)];

}

function subtitusi ($text){

    $alphabet = [

    “A” => 0,

    “B” => 1,

    “C” => 2,

    “D” => 3,

    “E” => 4,

    “F” => 5,

    “G” => 6,

    “H” => 7,

    “I” => 8,

    “J” => 9,

    “K” => 10,

    “L” => 11,

    “M” => 12,

    “N” => 13,

    “O” => 14,

    “P” => 15,

    “Q” => 16,

    “R” => 17,

    “S” => 18,

    “T” => 19,

    “U” => 20,

    “V” => 21,

    “W” => 22,

    “X” => 23,

    “Y” => 24,

    “Z” => 25,

  ];

  return $alphabet [strtoupper($text)];

}

?>