Analysis on encryption and decryption of PHP

This article mainly introduces the implementation method of PHP encryption and decryption, and analyzes the related techniques of PHP custom functions to implement string encryption and corresponding decryption in the form of examples. Friends in need can refer to the following

Examples of this article PHP encryption and decryption method. Share it with everyone for your reference, the details are as follows:

//加密
function string2secret($str)
{
 $key = "123";
 $td = mcrypt_module_open(MCRYPT_DES,'','ecb','');
 $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
 $ks = mcrypt_enc_get_key_size($td);
 $key = substr(md5($key), 0, $ks);
 mcrypt_generic_init($td, $key, $iv);
 $secret = mcrypt_generic($td, $str);
 mcrypt_generic_deinit($td);
 mcrypt_module_close($td);
 return $secret;
}
//解密
function secret2string($sec)
{
 $key = "123";
 $td = mcrypt_module_open(MCRYPT_DES,'','ecb','');
 $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
 $ks = mcrypt_enc_get_key_size($td);
 $key = substr(md5($key), 0, $ks);
 mcrypt_generic_init($td, $key, $iv);
 $string = mdecrypt_generic($td, $sec);
 mcrypt_generic_deinit($td);
 mcrypt_module_close($td);
 return trim($string);
}
echo secret2string(string2secret("11111111111111111"));
//显示结果是11111111111111111
echo &#39;<br>&#39;.string2secret("11111111111111111");
//显示乱码
echo &#39;<br>&#39;;
//$string:要加密的字符串 $isEncrypt=true:加密 $isEncrypt=false:解密
function dencrypt($string, $isEncrypt = true, $key = "KEY_SPACE") {
 if (!isset($string{0}) || !isset($key{0})) {
  return false;
 }
 $dynKey = $isEncrypt ? hash(&#39;sha1&#39;, microtime(true)) : substr($string, 0, 40);
 $fixedKey = hash(&#39;sha1&#39;, $key);
 $dynKeyPart1 = substr($dynKey, 0, 20);
 $dynKeyPart2 = substr($dynKey, 20);
 $fixedKeyPart1 = substr($fixedKey, 0, 20);
 $fixedKeyPart2 = substr($fixedKey, 20);
 $key = hash(&#39;sha1&#39;, $dynKeyPart1 . $fixedKeyPart1 . $dynKeyPart2 . $fixedKeyPart2);
 $string = $isEncrypt ? $fixedKeyPart1 . $string . $dynKeyPart2 : (isset($string{339}) ? gzuncompress(base64_decode(substr($string, 40))) : base64_decode(substr($string, 40)));
 $n = 0;
 $result = &#39;&#39;;
 $len = strlen($string);
 for ($n = 0; $n < $len; $n++) {
  $result .= chr(ord($string{$n}) ^ ord($key{$n % 40}));
 }
 return $isEncrypt ? $dynKey . str_replace(&#39;=&#39;, &#39;&#39;, base64_encode($n > 299 ? gzcompress($result) : $result)) : substr($result, 20, -20);
}
echo strlen(dencrypt("12345678912345"));

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