Implementation of custom encryption algorithms

The implementation of custom encryption algorithms This post was last edited by feiniaoflyer from 2014-05-011:16:02. symmetric encryption is used to transmit a secret ID, however, the string encrypted by the mcrypt_encrypt algorithm is too long, so to implement a custom encryption algorithm, the idea is as follows: First, calculate the sha1 key and get the first 32bit of the result, then follow the implementation of the custom encryption algorithm to be encrypted

This post was last edited by feiniaoflyer at 13:16:02, January 1 ,.

Symmetric encryption is used to transmit an ID that requires confidentiality. However, the string encrypted by the mcrypt_encrypt algorithm is too long. therefore, to implement a custom encryption algorithm, the idea is as follows:

First, calculate the sha1 of the key, obtain the first 32bit of the result, and then perform the XOR operation with the integer to be encrypted to obtain an encrypted 32bit result.

Result Group: 2bit | 6bit | 6bit | 6bit | 6bit | 6bit

Each group is named a0, a1, a2, a3, a4, and a5 respectively.

Define a 64-bit dictionary array

$ Dict = array ('1', '2', '3', '4', '5', '6', '7', '8 ', '9 ',
'A', 'B', 'C', 'D', 'e', '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', 'e', 'e', 'F', 'G', 'H', 'I', 'J ', 'K', 'L', 'M', 'n', 'O', 'P', 'Q', 'R', 'S', 'T ', 'U', 'V', 'W', 'X', 'y', 'z ',
'01', '02', '03 ');

When the values of each group are used as the subscript of the dictionary array, the encrypted result is: $ dict [a0]. $ dict [a1]. $ dict [a2]. $ dict [a3]. $ dict [a4]. $ dict [a5]

The encrypted result is a string of 6 to 12 characters. if the last three elements of the dictionary array are represented by other single characters, the result is a string of 6 characters.

I am not new to php and I am not familiar with the function library of php. please help me implement the encryption and decryption algorithm:

String encrypt (int id, string key)

Int decrypt (string text, string key)





------ Solution --------------------

------ Solution --------------------
Learning, amazing.
------ Solution --------------------
This is messy.

$id = 1234;
$key = 'aaa';
for($i=1; $i<100; $i++) {
  printf("%-10d %s %s\n", $id, $s = encrypt($id++, $key), decrypt( $s, $key));
}

function encrypt($id, $key) {
  $dict = array('1','2','3','4','5','6','7','8','9',
    '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',
    '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',
    '-','=','*'
  );
  $n = rand(0, 15);
  srand($n);
  $key = current(unpack('L', substr(sha1($key, 1), $n)));
  $id ^= $key;
  $t = str_split(sprintf('%04b%032b', $n, $id), 6);
  foreach($t as $i=>&$v) {
    $v = $dict[bindec($v)];
    if($i == 0) shuffle($dict);
  }
  return join($t);
}

function decrypt($s, $key) {
  $dict = array('1','2','3','4','5','6','7','8','9',
    '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',
    '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',
    '-','=','*'
  );
  $m = array_search($s{0}, $dict);
  $n = $m >> 2;
  srand($n);
  shuffle($dict);
  $dict = array_flip($dict);
  foreach(str_split($s) as $i=>$c) {
    $r[] = sprintf('%06b', $i==0 ? $m&0x03 : $dict[$c]);
  }    
  $id = bindec(join($r));
  $key = current(unpack('L', substr(sha1($key, 1), $n)));
  return $id ^ $key;
}

1234       4rHK4B 1234
1235       oD2LN* 1235
1236       wqkf8u 1236
1237       6k=GVU 1237
1238       bxeCr* 1238
1239       =W-AOi 1239
1240       IiQ3e1 1240
1241       z6uMMA 1241
1242       WLcnd8 1242
1243       Rizj*M 1243
1244       4rHK47 1244
1245       oD2LNT 1245
1246       wqkf8Z 1246
1247       6k=GVJ 1247
1248       bxeCrE 1248
1249       =W-AOP 1249
1250       IiQ3et 1250
1251       z6uMMP 1251
1252       WLcndU 1252
1253       Rizj*p 1253
1254       4rHK4s 1254
1255       oD2LNs 1255
1256       wqkf84 1256
1257       6k=GVn 1257
1258       bxeCrL 1258
1259       =W-AOT 1259
1260       IiQ3ex 1260
1261       z6uMM1 1261
1262       WLcndD 1262
1263       Rizj*s 1263
1264       4rHK4h 1264
1265       oD2LNq 1265
1266       wqkf83 1266