PHP加密解密实例分析

//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11111111111111111echo '<br>'.string2secret("11111111111111111");//显示乱码echo '<br>';//$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 = $isEncrypt ? hash('sha1', microtime(true)) : substr($string, 0, 40); $fixedKey = hash('sha1', $key); $dynKeyPart1 = substr($dynKey, 0, 20); $dynKeyPart2 = substr($dynKey, 20); $fixedKeyPart1 = substr($fixedKey, 0, 20); $fixedKeyPart2 = substr($fixedKey, 20); $key = hash('sha1', $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 = ''; $len = strlen($string); for ($n = 0; $n < $len; $n++) {  $result .= chr(ord($string{$n}) ^ ord($key{$n % 40})); } return $isEncrypt ? $dynKey . str_replace('=', '', base64_encode($n > 299 ? gzcompress($result) : $result)) : substr($result, 20, -20);}echo strlen(dencrypt("12345678912345"));