How to encrypt string without mcrypt library in php

Question

in function need key to encrypt string without mcrypt libraly in php

function encrypt($str, $pass){
        $str_arr = str_split($str);
        $pass_arr = str_split($pass);
        $add = 0;
        $div = strlen($str) / strlen($pass);
        while ($add <= $div) {
             $newpass .= $pass;
             $add++;
        }
        $pass_arr = str_split($newpass);
        foreach($str_arr as $key =>$asc) {
            $pass_int = ord($pass_arr[$key]);
            $str_int = ord($asc);
            $int_add = $str_int + $pass_int;
            $ascii .= chr($int_add);
        }
        return $ascii;
    }

    function decrypt($enc, $pass){
        $enc_arr = str_split($enc);
        $pass_arr = str_split($pass);
        $add = 0;
        $div = strlen($enc) / strlen($pass);
        while ($add <= $div) {
            $newpass .= $pass;
            $add++;
        }
        $pass_arr = str_split($newpass);
        foreach($enc_arr as $key =>$asc) {
            $pass_int = ord($pass_arr[$key]);
            $enc_int = ord($asc);
            $str_int = $enc_int - $pass_int;
            $ascii .= chr($str_int);
        }
        return $ascii;
    }

in this not work for i character i test it

Say what? Need more information for this question.

Andy Moore
– Andy Moore

2009-04-29 04:52:12 +00:00
Commented Apr 29, 2009 at 4:52 — Andy Moore
– Andy Moore, Commented Apr 29, 2009 at 4:52

jlogsdon · Accepted Answer · 2009-04-29 15:40:09Z

6

Here's another method:

$key = 'the quick brown fox jumps over the lazy ';
$string = 'Hey we are testing encryption';

echo enc_encrypt($string, $key)."\n";
echo enc_decrypt(enc_encrypt($string, $key), $key)."\n";

function enc_encrypt($string, $key) {
    $result = '';
    for($i = 0; $i < strlen($string); $i++) {
        $char = substr($string, $i, 1);
        $keychar = substr($key, ($i % strlen($key))-1, 1);
        $char = chr(ord($char) + ord($keychar));
        $result .= $char;
    }

    return base64_encode($result);
}

function enc_decrypt($string, $key) {
    $result = '';
    $string = base64_decode($string);

    for($i = 0; $i < strlen($string); $i++) {
        $char = substr($string, $i, 1);
        $keychar = substr($key, ($i % strlen($key))-1, 1);
        $char = chr(ord($char) - ord($keychar));
        $result .= $char;
    }

    return $result;
}

Again, don't expect this to be very secure.

answered Apr 29, 2009 at 15:40

jlogsdon

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2 Comments

trante Over a year ago

What about urlencoding the string in the beginning of the encrypt function, and urldecoding in the beginning of decrypt function? else result can contain "+", "=" and "/" characters.

trante Over a year ago

I suppose better way is, adding $string=urldecode($string); to enc_decrypt and, adding return urlencode(base64_encode($result)); to enc_encrypt

scragar · Accepted Answer · 2009-04-29 14:11:16Z

This code is rather inefficient, I'm not surprised it doesn't give intended results.

echo RotEncrypt('cheese', 'pie') . "\n<br>\n"
    .RotDecrypt(RotEncrypt('cheese', 'pie'), 'pie');
// ÓÑÊÕÜÊ
// cheese

function RotEncrypt($str, $pass){
   $pass = str_split(str_pad('', strlen($str), $pass, STR_PAD_RIGHT));
   $stra = str_split($str);
   foreach($stra as $k=>$v){
     $tmp = ord($v)+ord($pass[$k]);
     $stra[$k] = chr( $tmp > 255 ?($tmp-256):$tmp);
   }
   return join('', $stra);
}
function RotDecrypt($str, $pass){
   $pass = str_split(str_pad('', strlen($str), $pass, STR_PAD_RIGHT));
   $stra = str_split($str);
   foreach($stra as $k=>$v){
     $tmp = ord($v)-ord($pass[$k]);
     $stra[$k] = chr( $tmp < 0 ?($tmp+256):$tmp);
   }
   return join('', $stra);
}

Tested and it appears to work fine for me.

Either way I feel I should warn you that this is a really insecure form of encryption, most passwords use the same sets of characters and a fairly small range of lengths, which makes this system very vulnerable to people being able to work out with a fairly good level of accuracy the password.

trante · Accepted Answer · 2012-06-01 17:15:39Z

4

You can also try this:

http://phpseclib.sourceforge.net/

or this:

http://www.phpclasses.org/package/1610-PHP-Symetric-encryption-of-data-using-only-PHP-code.html

or even this:

http://px.sklar.com/code.html/id=1287

answered Jun 1, 2012 at 17:15

trante

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Comments

tiriana · Accepted Answer · 2011-09-13 09:49:07Z

1

I used jlogsdon enc_encrypt and enc_decrypt in prestashop 1.4.4.1 to wrap encrypt and decrypt methods from Rijndael class, witch are using mcrypt. I didn'e check if enc_encrypt and enc_decrypt give exacly the same resulst as mcrypt_encrypt and mcrypt_decrypt, but they seem to work in prestashop 1.4.4.1. Thanks a lot.

answered Sep 13, 2011 at 9:49

tiriana

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Comments

Ariston Cordeiro · Accepted Answer · 2019-04-04 12:35:46Z

The question is old but, as PHP 7 don't have mcrypt, I had the same problem. The best solution I found is using OpenSSL. It is built into PHP and you don't need any external library.

To encrypt:

function encrypt($key, $payload) {
  $iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length('aes-256-cbc'));
  $encrypted = openssl_encrypt($payload, 'aes-256-cbc', $key, 0, $iv);
  return base64_encode($encrypted . '::' . $iv);
}

To decrypt:

function decrypt($key, $garble) {
    list($encrypted_data, $iv) = explode('::', base64_decode($garble), 2);
    return openssl_decrypt($encrypted_data, 'aes-256-cbc', $key, 0, $iv);
}

Reference link: https://www.shift8web.ca/2017/04/how-to-encrypt-and-execute-your-php-code-with-mcrypt/

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