PHP Source Code Analysis DZX1.5 Cryptographic decryption function Authcode Usage _php tutorial

PHP source code Analysis of DZX1.5 cryptographic decryption function Authcode usage

This article describes the PHP source code Analysis of the DZX1.5 cryptographic decryption function Authcode usage. Share to everyone for your reference. The specific analysis is as follows:

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$authkey = "; /** * @param string $string: Input plaintext (or ciphertext) that needs to be encrypted (or decrypted) * @param string $operation: ' DECODE ' or other, where the default is to decrypt, input other means to encrypt * @param string $key: Add decryption key * @param int $expiry: expiry date */ function Authcode ($string, $operation = ' DECODE ', $key = ", $expiry = 0) { Global $authkey; $ckey _length = 4; $key = MD5 ($key! = "? $key: $authkey); $keya = MD5 (substr ($key, 0, 16)); $KEYB = MD5 (substr ($key, 16, 16)); $KEYC = $ckey _length? ($operation = = ' DECODE '? substr ($string, 0, $ckey _length): substr (MD5 (Microtime ()),-$ckey _length)): "; $cryptkey = $keya. MD5 ($keya. $KEYC); $key _length = strlen ($cryptkey); $string = $operation = = = ' DECODE '? Base64_decode (substr ($string, $ckey _length)): sprintf ('%010d ', $expiry? $expiry + Time (): 0). substr (MD5 ($string. $keyb ), 0, (+). $string; $string _length = strlen ($string); $result = "; $box = Range (0, 255); $rndkey = Array (); for ($i = 0; $i <= 255; $i + +) { $rndkey [$i] = Ord ($cryptkey [$i% $key _length]); } for ($j = $i = 0; $i < $i + +) { $j = ($j + $box [$i] + $rndkey [$i])% 256; $tmp = $box [$i]; $box [$i] = $box [$j]; $box [$j] = $tmp; } for ($a = $j = $i = 0; $i < $string _length; $i + +) { $a = ($a + 1)% 256; $j = ($j + $box [$a])% 256; $tmp = $box [$a]; $box [$a] = $box [$j]; $box [$j] = $tmp; $result. = Chr (ord ($string [$i]) ^ ($box [($box [$a] + $box [$j])% 256])); } if ($operation = = ' DECODE ') { if (substr ($result, 0, ten) = = 0 | | substr ($result, 0,)-time () > 0) && substr ($result, ten, +) = = SUBSTR (MD 5 (substr ($result, +). $keyb), 0, 16)) { Return substr ($result, 26); } else { Return '; } } else { Return $KEYC. Str_replace (' = ', ' ', Base64_encode ($result)); } } $STR = ' 1234 '; $key = ' 1234 '; echo "Clear text:". $str; echo " "; echo "key:". $key; $encode = Authcode ($str, ' one ', $key); echo " "; echo "Ciphertext after encryption:" $ENCODE; echo " "; $decode = Authcode ($encode, ' decode ', $key); echo "decrypted plaintext:". $decode; /*end of php*/

The results of the operation are as follows:

PlainText: 1234

Key: 1234

Ciphertext after encryption: A52F67EXZGVY0HTQBO4VOREHQ3WXNL6E2ZLX75JGFOJW

Decrypted plaintext: 1234

I hope this article is helpful to everyone's PHP programming.

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