string md5 ( string $str [, bool $raw_output = false ] ); //MD5加密,输入任意长度字符串返回一个唯一的32位字符

md5(md5($password).‘sdva‘); 

string crypt ( string $str [, string $salt ] ) //第一个为需要加密的字符串，第二个为盐值（就是加密干扰值，如果没有提供，则默认由PHP自动生成）；返回散列后的字符串或一个少于 13 字符的字符串，后者为了区别盐值。

<?php $password=‘testtest.com‘; echo crypt($password); //输出:$1$DZ3.QX2.$CQZ8I.OfeepKYrWp0oG8L1 /*第二个$与第三个$之间的八个字符是由PHP生成的，每刷新一次就变一次 */ echo "<hr>"; ?echo crypt($password,"testtest"); //输出：tesGeyALKYm3A //当我们要加自定义的盐值时，如例子中的testtest作为第二个参数直接加入， 超出两位字符的会截取前两位 echo "<hr>"; ?echo ?crypt($password,‘$1$testtest$‘); //输出：$1$testtest$DsiRAWGTHiVH3O0HSHGoL1 /*crypt加密函数有多种盐值加密支持，以上例子展示的是MD5散列作为盐值，该方式下 盐值以$1$$的形式加入，如例子中的testtest加在后两个$符之间， 超出八位字符的会截取前八位，总长为12位;crypt默认就是这种形式。 */ echo "<hr>"; //crypt还有多种盐值加密支持,详见手册

string sha1 ( string $str [, bool $raw_output = false ]); //跟md5很像，不同的是sha1()默认情况下返回40个字符的散列值，传入参数性质一样，第一个为加密的字符串，第二个为raw_output的布尔值，默认为false，如果设置为true，sha1()则会返回原始的20 位原始格式报文摘要

<?php /** ?* 使用openssl实现非对称加密 ?* @since 2010-07-08 ?*/ class Rsa { ????/** ?????* private key ?????*/ ????private $_privKey; ????/** ?????* public key ?????*/ ????private $_pubKey; ????/** ?????* the keys saving path ?????*/ ????private $_keyPath; ????/** ?????* the construtor,the param $path is the keys saving path ?????*/ ????public function __construct($path) { ????????if (empty($path) || !is_dir($path)) { ????????????throw new Exception(‘Must set the keys save path‘); ????????} ????????$this->_keyPath = $path; ????} ????/** ?????* create the key pair,save the key to $this->_keyPath ?????*/ ????public function createKey() { ????????$r = openssl_pkey_new(); ????????openssl_pkey_export($r, $privKey); ????????file_put_contents($this->_keyPath . DIRECTORY_SEPARATOR . ‘priv.key‘, $privKey); ????????$this->_privKey = openssl_pkey_get_public($privKey); ????????$rp = openssl_pkey_get_details($r); ????????$pubKey = $rp[‘key‘]; ????????file_put_contents($this->_keyPath . DIRECTORY_SEPARATOR . ‘pub.key‘, $pubKey); ????????$this->_pubKey = openssl_pkey_get_public($pubKey); ????} ????/** ?????* setup the private key ?????*/ ????public function setupPrivKey() { ????????if (is_resource($this->_privKey)) { ????????????return true; ????????} ????????$file = $this->_keyPath . DIRECTORY_SEPARATOR . ‘priv.key‘; ????????$prk = file_get_contents($file); ????????$this->_privKey = openssl_pkey_get_private($prk); ????????return true; ????} ????/** ?????* setup the public key ?????*/ ????public function setupPubKey() { ????????if (is_resource($this->_pubKey)) { ????????????return true; ????????} ????????$file = $this->_keyPath . DIRECTORY_SEPARATOR . ‘pub.key‘; ????????$puk = file_get_contents($file); ????????$this->_pubKey = openssl_pkey_get_public($puk); ????????return true; ????} ????/** ?????* encrypt with the private key ?????*/ ????public function privEncrypt($data) { ????????if (!is_string($data)) { ????????????return null; ????????} ????????$this->setupPrivKey(); ????????$r = openssl_private_encrypt($data, $encrypted, $this->_privKey); ????????if ($r) { ????????????return base64_encode($encrypted); ????????} ????????return null; ????} ????/** ?????* decrypt with the private key ?????*/ ????public function privDecrypt($encrypted) { ????????if (!is_string($encrypted)) { ????????????return null; ????????} ????????$this->setupPrivKey(); ????????$encrypted = base64_decode($encrypted); ????????$r = openssl_private_decrypt($encrypted, $decrypted, $this->_privKey); ????????if ($r) { ????????????return $decrypted; ????????} ????????return null; ????} ????/** ?????* encrypt with public key ?????*/ ????public function pubEncrypt($data) { ????????if (!is_string($data)) { ????????????return null; ????????} ????????$this->setupPubKey(); ????????$r = openssl_public_encrypt($data, $encrypted, $this->_pubKey); ????????if ($r) { ????????????return base64_encode($encrypted); ????????} ????????return null; ????} ????/** ?????* decrypt with the public key ?????*/ ????public function pubDecrypt($crypted) { ????????if (!is_string($crypted)) { ????????????return null; ????????} ????????$this->setupPubKey(); ????????$crypted = base64_decode($crypted); ????????$r = openssl_public_decrypt($crypted, $decrypted, $this->_pubKey); ????????if ($r) { ????????????return $decrypted; ????????} ????????return null; ????} ????public function __destruct() { ????????@fclose($this->_privKey); ????????@fclose($this->_pubKey); ????} } //以下是一个简单的测试demo，如果不需要请删除 $rsa = new Rsa(‘ssl-key‘); //私钥加密，公钥解密 echo ‘source：我是老鳖<br />‘; $pre = $rsa->privEncrypt(‘我是老鳖‘); echo ‘private encrypted:<br />‘ . $pre . ‘<br />‘; $pud = $rsa->pubDecrypt($pre); echo ‘public decrypted:‘ . $pud . ‘<br />‘; //公钥加密，私钥解密 echo ‘source:干IT的<br />‘; $pue = $rsa->pubEncrypt(‘干IT的‘); echo ‘public encrypt:<br />‘ . $pue . ‘<br />‘; $prd = $rsa->privDecrypt($pue); echo ‘private decrypt:‘ . $prd; ?> ?

string urlencode ( string $str ) ?/* 1. 一个参数，传入要加密的字符串（通常应用于对URL的加密） 2. urlencode为双向加密，可以用urldecode来加密（严格意义上来说，不算真正的加密,更像是一种编码方式） 3. 返回字符串，此字符串中除了 -_. 之外的所有非字母数字字符都将被替换成百分号（%）后跟两位十六进制数，空格则编码为加号（+）。 */

<?php $pre_url_encode="zhougang.com?username=zhougang&password=zhou"; //在实际开发中，我们很多时候要构造这种URL，这是没有问题的 $url_decode ???="zhougang.com?username=zhou&gang&password=zhou";//但是这种情况下用$_GET()来接受是会出问题的; /* Array ( ??[username] => zhou ??[gang] => ???[password] => zhou ) ?*/ ??//如下解决问题: $username="zhou&gang"; $url_decode="zhougang.com?username=".urlencode($username)."&password=zhou"; ?>

$data=file_get_contents($filename); echo base64_encode($data); /*然后你查看网页源码就会得到一大串base64的字符串， 再用base64_decode()还原就可以得到图片。这也可以作为移动端上传图片的处理方案之一（但是不建议这样做哈） */

<?php function authcode($string, $operation = ‘DECODE‘, $key = ‘‘, $expiry = 0) { ???????// 动态密匙长度，相同的明文会生成不同密文就是依靠动态密匙 ???????$ckey_length = 4; ???????????????// 密匙 ???????$key = md5($key ? $key : $GLOBALS[‘discuz_auth_key‘]); ???????????????// 密匙a会参与加解密 ???????$keya = md5(substr($key, 0, 16)); ???????// 密匙b会用来做数据完整性验证 ???????$keyb = md5(substr($key, 16, 16)); ???????// 密匙c用于变化生成的密文 ???????$keyc = $ckey_length ? ($operation == ‘DECODE‘ ? substr($string, 0, $ckey_length): ?substr(md5(microtime()), -$ckey_length)) : ‘‘; ???????// 参与运算的密匙 ???????$cryptkey = $keya.md5($keya.$keyc); ???????$key_length = strlen($cryptkey); ???????// 明文，前10位用来保存时间戳，解密时验证数据有效性，10到26位用来保存$keyb(密匙b)， ?//解密时会通过这个密匙验证数据完整性 ???????// 如果是解码的话，会从第$ckey_length位开始，因为密文前$ckey_length位保存 动态密匙，以保证解密正确 ???????$string = $operation == ‘DECODE‘ ? base64_decode(substr($string, $ckey_length)) : ??sprintf(‘%010d‘, $expiry ? $expiry + time() : 0).substr(md5($string.$keyb), 0, 16).$string; ???????$string_length = strlen($string); ???????$result = ‘‘; ???????$box = range(0, 255); ???????$rndkey = array(); ???????// 产生密匙簿 ???????for($i = 0; $i <= 255; $i++) { ???????????$rndkey[$i] = ord($cryptkey[$i % $key_length]); ???????} ???????// 用固定的算法，打乱密匙簿，增加随机性，好像很复杂，实际上对并不会增加密文的强度 ???????for($j = $i = 0; $i < 256; $i++) { ???????????$j = ($j + $box[$i] + $rndkey[$i]) % 256; ???????????$tmp = $box[$i]; ???????????$box[$i] = $box[$j]; ???????????$box[$j] = $tmp; ???????} ???????// 核心加解密部分 ???????for($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] = $tmp; ???????????// 从密匙簿得出密匙进行异或，再转成字符 ???????????$result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256])); ???????} ???????if($operation == ‘DECODE‘) { ??????????// 验证数据有效性，请看未加密明文的格式 ???????????if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && ??substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) { ???????????????return substr($result, 26); ???????????} else { ???????????????return ‘‘; ???????????} ???????} else { ???????????// 把动态密匙保存在密文里，这也是为什么同样的明文，生产不同密文后能解密的原因 ???????????// 因为加密后的密文可能是一些特殊字符，复制过程可能会丢失，所以用base64编码 ???????????return $keyc.str_replace(‘=‘, ‘‘, base64_encode($result)); ???????} ???} 

<?php //$string：需要加密解密的字符串；$operation：判断是加密还是解密，E表示加密，D表示解密；$key：密匙 function encrypt($string,$operation,$key=‘‘){ ?????$key=md5($key); ?????$key_length=strlen($key); ???????$string=$operation==‘D‘?base64_decode($string):substr(md5($string.$key),0,8).$string; ?????$string_length=strlen($string); ?????$rndkey=$box=array(); ?????$result=‘‘; ?????for($i=0;$i<=255;$i++){ ????????????$rndkey[$i]=ord($key[$i%$key_length]); ?????????$box[$i]=$i; ?????} ?????for($j=$i=0;$i<256;$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($operation==‘D‘){ ?????????if(substr($result,0,8)==substr(md5(substr($result,8).$key),0,8)){ ?????????????return substr($result,8); ?????????}else{ ?????????????return‘‘; ?????????} ?????}else{ ?????????return str_replace(‘=‘,‘‘,base64_encode($result)); ?????} ?} ?>