同样是一道面试答错的问题，面试官问我非对称加密算法中有哪些经典的算法？ 当时我愣了一下，因为我把非对称加密与单项散列加密的概念弄混淆了，所以更不用说什么非对称加密算法中有什么经典算法，结果当然也让面试官愣了一下，所以今天就花点时间说说PHP中的信息加密技术
信息加密技术的分类
单项散列加密技术(不可逆的加密)
属于摘要算法，不是一种加密算法，作用是把任意长的输入字符串变化成固定长的输出串的一种函数
MD5
string md5 ( string $str [, bool $raw_output = false ] ); //MD5加密,输入任意长度字符串返回一个唯一的32位字符
md5()为单向加密，没有逆向解密算法，但是还是可以对一些常见的字符串通过收集，枚举，碰撞等方法破解;所以为了让其破解起来更麻烦一些,所以我们一般加一点盐值(salt)并双重MD5;
md5(md5($password).'sdva');
sdva就是盐值,该盐值应该是随机的,比如md5常用在密码加密上,所以在注册的时候我会随机生成这个字符串,然后通过上面的方法来双重加密一下;
Crypt
很少看到有人用这个函数,如果要用的话有可能是用在对称或非对称的算法里面,了解一下既可;
string crypt ( string $str [, string $salt ] ) //第一个为需要加密的字符串，第二个为盐值就是加密干扰值，如果没有提供，则默认由PHP自动生成）；返回散列后的字符串或一个少于 13 字符的字符串，后者为了区别盐值
<ol class="dp-j"><li class="alt"><span><span><?php </span></span></li><li><span>$password=<span class="string">'testtest.com'</span><span>; </span></span></li><li class="alt"><span>echo crypt($password); </span></li><li><span><span class="comment">//输出:$1$DZ3.QX2.$CQZ8I.OfeepKYrWp0oG8L1</span><span> </span></span></li><li class="alt"><span><span class="comment">/*第二个$与第三个$之间的八个字符是由PHP生成的，每刷新一次就变一次</span> </span></li><li><span><span class="comment">*/</span><span> </span></span></li><li class="alt"><span>echo <span class="string">"<hr>"</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span>echo crypt($password,<span class="string">"testtest"</span><span>); </span></span></li><li><span><span class="comment">//输出：tesGeyALKYm3A</span><span> </span></span></li><li class="alt"><span><span class="comment">//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</span><span> </span></span></li><li><span>echo <span class="string">"<hr>"</span><span>; </span></span></li><li class="alt"><span> </span></li><li><span>echo crypt($password,<span class="string">'$1$testtest$'</span><span>); </span></span></li><li class="alt"><span><span class="comment">//输出：$1$testtest$DsiRAWGTHiVH3O0HSHGoL1</span><span> </span></span></li><li><span><span class="comment">/*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</span> </span></li><li class="alt"><span><span class="comment">盐值以$1$$的形式加入，如例子中的testtest加在后两个$符之间，</span> </span></li><li><span><span class="comment">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。</span> </span></li><li class="alt"><span><span class="comment">*/</span><span> </span></span></li><li><span>echo <span class="string">"<hr>"</span><span>; </span></span></li><li class="alt"><span><span class="comment">//crypt还有多种盐值加密支持,详见手册</span><span> </span></span></li><li><span> </span></li><li class="alt"><span>Sha1加密： </span></li><li><span> </span></li><li class="alt"><span>string sha1 ( string $str [, bool $raw_output = <span class="keyword">false</span><span> ]); </span><span class="comment">//跟md5很像，不同的是sha1()默认情况下返回40个字符的散列值，传入参数性质一样，第一个为加密的字符串，第二个为raw_output的布尔值，默认为false，如果设置为true，sha1()则会返回原始的20 位原始格式报文摘要</span><span> </span></span></li><li><span><?php </span></li><li class="alt"><span>$my_intro=<span class="string">"zhouxiaogang"</span><span>; </span></span></li><li><span>echo sha1($my_intro); <span class="comment">// b6773e8c180c693d9f875bcf77c1202a243e8594</span><span> </span></span></li><li class="alt"><span>echo <span class="string">"<hr>"</span><span>; </span></span></li><li><span><span class="comment">//当然，可以将多种加密算法混合使用</span><span> </span></span></li><li class="alt"><span>echo md5(sha1($my_intro)); </span></li><li><span><span class="comment">//输出：54818bd624d69ac9a139bf92251e381d</span><span> </span></span></li><li class="alt"><span><span class="comment">//这种方式的双重加密也可以提高数据的安全性</span><span> </span></span></li></ol>
非对称加密
非对称加密算法需要两个密钥来进行加密和解密，这两个秘钥是公开密钥public key，简称公钥）和私有密钥private key，简称私钥）;
如图所示，甲乙之间使用非对称加密的方式完成了重要信息的安全传输。
在传输过程中，即使攻击者截获了传输的密文，并得到了乙的公钥，也无法破解密文，因为只有乙的私钥才能解密密文
同样，如果乙要回复加密信息给甲，那么需要甲先公布甲的公钥给乙用于加密，甲自己保存甲的私钥用于解密。
在非对称加密中使用的主要算法有：RSA、Elgamal、背包算法、Rabin、D-H、ECC椭圆曲线加密算法）等。 其中我们最见的算法是RSA算法
以下是从网上摘抄的一段PHP通过openssl实现非对称加密的算法
<ol class="dp-c"><li class="alt"><span><span><?php </span></span></li><li><span><span class="comment">/**</span> </span></li><li class="alt"><span><span class="comment">* 使用openssl实现非对称加密</span> </span></li><li><span><span class="comment">* @since 2010-07-08</span> </span></li><li class="alt"><span><span class="comment">*/</span><span> </span></span></li><li><span><span class="keyword">class</span><span> Rsa { </span></span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * private key</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">private</span><span> </span><span class="vars">$_privKey</span><span>; </span></span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * public key</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">private</span><span> </span><span class="vars">$_pubKey</span><span>; </span></span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * the keys saving path</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">private</span><span> </span><span class="vars">$_keyPath</span><span>; </span></span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * the construtor,the param $path is the keys saving path</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> __construct(</span><span class="vars">$path</span><span>) { </span></span></li><li class="alt"><span> <span class="keyword">if</span><span> (</span><span class="func">empty</span><span class="keyword">empty</span><span>(</span><span class="vars">$path</span><span>) || !</span><span class="func">is_dir</span><span>(</span><span class="vars">$path</span><span>)) { </span></span></li><li><span> <span class="keyword">throw</span><span> </span><span class="keyword">new</span><span> Exception(</span><span class="string">'Must set the keys save path'</span><span>); </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="vars">$this</span><span>->_keyPath = </span><span class="vars">$path</span><span>; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="comment">/**</span> </span></li><li class="alt"><span><span class="comment"> * create the key pair,save the key to $this->_keyPath</span> </span></li><li><span><span class="comment"> */</span><span> </span></span></li><li class="alt"><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> createKey() { </span></span></li><li><span> <span class="vars">$r</span><span> = openssl_pkey_new(); </span></span></li><li class="alt"><span> openssl_pkey_export(<span class="vars">$r</span><span>, </span><span class="vars">$privKey</span><span>); </span></span></li><li><span> <span class="func">file_put_contents</span><span>(</span><span class="vars">$this</span><span>->_keyPath . DIRECTORY_SEPARATOR . </span><span class="string">'priv.key'</span><span>, </span><span class="vars">$privKey</span><span>); </span></span></li><li class="alt"><span> <span class="vars">$this</span><span>->_privKey = openssl_pkey_get_public(</span><span class="vars">$privKey</span><span>); </span></span></li><li><span> <span class="vars">$rp</span><span> = openssl_pkey_get_details(</span><span class="vars">$r</span><span>); </span></span></li><li class="alt"><span> <span class="vars">$pubKey</span><span> = </span><span class="vars">$rp</span><span>[</span><span class="string">'key'</span><span>]; </span></span></li><li><span> <span class="func">file_put_contents</span><span>(</span><span class="vars">$this</span><span>->_keyPath . DIRECTORY_SEPARATOR . </span><span class="string">'pub.key'</span><span>, </span><span class="vars">$pubKey</span><span>); </span></span></li><li class="alt"><span> <span class="vars">$this</span><span>->_pubKey = openssl_pkey_get_public(</span><span class="vars">$pubKey</span><span>); </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * setup the private key</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> setupPrivKey() { </span></span></li><li class="alt"><span> <span class="keyword">if</span><span> (</span><span class="func">is_resource</span><span>(</span><span class="vars">$this</span><span>->_privKey)) { </span></span></li><li><span> <span class="keyword">return</span><span> true; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="vars">$file</span><span> = </span><span class="vars">$this</span><span>->_keyPath . DIRECTORY_SEPARATOR . </span><span class="string">'priv.key'</span><span>; </span></span></li><li class="alt"><span> <span class="vars">$prk</span><span> = </span><span class="func">file_get_contents</span><span>(</span><span class="vars">$file</span><span>); </span></span></li><li><span> <span class="vars">$this</span><span>->_privKey = openssl_pkey_get_private(</span><span class="vars">$prk</span><span>); </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> true; </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * setup the public key</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> setupPubKey() { </span></span></li><li class="alt"><span> <span class="keyword">if</span><span> (</span><span class="func">is_resource</span><span>(</span><span class="vars">$this</span><span>->_pubKey)) { </span></span></li><li><span> <span class="keyword">return</span><span> true; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="vars">$file</span><span> = </span><span class="vars">$this</span><span>->_keyPath . DIRECTORY_SEPARATOR . </span><span class="string">'pub.key'</span><span>; </span></span></li><li class="alt"><span> <span class="vars">$puk</span><span> = </span><span class="func">file_get_contents</span><span>(</span><span class="vars">$file</span><span>); </span></span></li><li><span> <span class="vars">$this</span><span>->_pubKey = openssl_pkey_get_public(</span><span class="vars">$puk</span><span>); </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> true; </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * encrypt with the private key</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> privEncrypt(</span><span class="vars">$data</span><span>) { </span></span></li><li class="alt"><span> <span class="keyword">if</span><span> (!</span><span class="func">is_string</span><span>(</span><span class="vars">$data</span><span>)) { </span></span></li><li><span> <span class="keyword">return</span><span> null; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="vars">$this</span><span>->setupPrivKey(); </span></span></li><li class="alt"><span> <span class="vars">$r</span><span> = openssl_private_encrypt(</span><span class="vars">$data</span><span>, </span><span class="vars">$encrypted</span><span>, </span><span class="vars">$this</span><span>->_privKey); </span></span></li><li><span> <span class="keyword">if</span><span> (</span><span class="vars">$r</span><span>) { </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> </span><span class="func">base64_encode</span><span>(</span><span class="vars">$encrypted</span><span>); </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="keyword">return</span><span> null; </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="comment">/**</span> </span></li><li><span><span class="comment"> * decrypt with the private key</span> </span></li><li class="alt"><span><span class="comment"> */</span><span> </span></span></li><li><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> privDecrypt(</span><span class="vars">$encrypted</span><span>) { </span></span></li><li class="alt"><span> <span class="keyword">if</span><span> (!</span><span class="func">is_string</span><span>(</span><span class="vars">$encrypted</span><span>)) { </span></span></li><li><span> <span class="keyword">return</span><span> null; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="vars">$this</span><span>->setupPrivKey(); </span></span></li><li class="alt"><span> <span class="vars">$encrypted</span><span> = </span><span class="func">base64_decode</span><span>(</span><span class="vars">$encrypted</span><span>); </span></span></li><li><span> <span class="vars">$r</span><span> = openssl_private_decrypt(</span><span class="vars">$encrypted</span><span>, </span><span class="vars">$decrypted</span><span>, </span><span class="vars">$this</span><span>->_privKey); </span></span></li><li class="alt"><span> <span class="keyword">if</span><span> (</span><span class="vars">$r</span><span>) { </span></span></li><li><span> <span class="keyword">return</span><span> </span><span class="vars">$decrypted</span><span>; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="keyword">return</span><span> null; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="comment">/**</span> </span></li><li class="alt"><span><span class="comment"> * encrypt with public key</span> </span></li><li><span><span class="comment"> */</span><span> </span></span></li><li class="alt"><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> pubEncrypt(</span><span class="vars">$data</span><span>) { </span></span></li><li><span> <span class="keyword">if</span><span> (!</span><span class="func">is_string</span><span>(</span><span class="vars">$data</span><span>)) { </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> null; </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="vars">$this</span><span>->setupPubKey(); </span></span></li><li><span> <span class="vars">$r</span><span> = openssl_public_encrypt(</span><span class="vars">$data</span><span>, </span><span class="vars">$encrypted</span><span>, </span><span class="vars">$this</span><span>->_pubKey); </span></span></li><li class="alt"><span> <span class="keyword">if</span><span> (</span><span class="vars">$r</span><span>) { </span></span></li><li><span> <span class="keyword">return</span><span> </span><span class="func">base64_encode</span><span>(</span><span class="vars">$encrypted</span><span>); </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="keyword">return</span><span> null; </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="comment">/**</span> </span></li><li class="alt"><span><span class="comment"> * decrypt with the public key</span> </span></li><li><span><span class="comment"> */</span><span> </span></span></li><li class="alt"><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> pubDecrypt(</span><span class="vars">$crypted</span><span>) { </span></span></li><li><span> <span class="keyword">if</span><span> (!</span><span class="func">is_string</span><span>(</span><span class="vars">$crypted</span><span>)) { </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> null; </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="vars">$this</span><span>->setupPubKey(); </span></span></li><li><span> <span class="vars">$crypted</span><span> = </span><span class="func">base64_decode</span><span>(</span><span class="vars">$crypted</span><span>); </span></span></li><li class="alt"><span> <span class="vars">$r</span><span> = openssl_public_decrypt(</span><span class="vars">$crypted</span><span>, </span><span class="vars">$decrypted</span><span>, </span><span class="vars">$this</span><span>->_pubKey); </span></span></li><li><span> <span class="keyword">if</span><span> (</span><span class="vars">$r</span><span>) { </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> </span><span class="vars">$decrypted</span><span>; </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="keyword">return</span><span> null; </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="keyword">public</span><span> </span><span class="keyword">function</span><span> __destruct() { </span></span></li><li><span> @fclose(<span class="vars">$this</span><span>->_privKey); </span></span></li><li class="alt"><span> @fclose(<span class="vars">$this</span><span>->_pubKey); </span></span></li><li><span> } </span></li><li class="alt"><span>} </span></li><li><span><span class="comment">//以下是一个简单的测试demo，如果不需要请删除</span><span> </span></span></li><li class="alt"><span><span class="vars">$rsa</span><span> = </span><span class="keyword">new</span><span> Rsa(</span><span class="string">'ssl-key'</span><span>); </span></span></li><li><span><span class="comment">//私钥加密，公钥解密</span><span> </span></span></li><li class="alt"><span><span class="func">echo</span><span> </span><span class="string">'source：我是老鳖<br />'</span><span>; </span></span></li><li><span><span class="vars">$pre</span><span> = </span><span class="vars">$rsa</span><span>->privEncrypt(</span><span class="string">'我是老鳖'</span><span>); </span></span></li><li class="alt"><span><span class="func">echo</span><span> </span><span class="string">'private encrypted:<br />'</span><span> . </span><span class="vars">$pre</span><span> . </span><span class="string">'<br />'</span><span>; </span></span></li><li><span><span class="vars">$pud</span><span> = </span><span class="vars">$rsa</span><span>->pubDecrypt(</span><span class="vars">$pre</span><span>); </span></span></li><li class="alt"><span><span class="func">echo</span><span> </span><span class="string">'public decrypted:'</span><span> . </span><span class="vars">$pud</span><span> . </span><span class="string">'<br />'</span><span>; </span></span></li><li><span><span class="comment">//公钥加密，私钥解密</span><span> </span></span></li><li class="alt"><span><span class="func">echo</span><span> </span><span class="string">'source:干IT的<br />'</span><span>; </span></span></li><li><span><span class="vars">$pue</span><span> = </span><span class="vars">$rsa</span><span>->pubEncrypt(</span><span class="string">'干IT的'</span><span>); </span></span></li><li class="alt"><span><span class="func">echo</span><span> </span><span class="string">'public encrypt:<br />'</span><span> . </span><span class="vars">$pue</span><span> . </span><span class="string">'<br />'</span><span>; </span></span></li><li><span><span class="vars">$prd</span><span> = </span><span class="vars">$rsa</span><span>->privDecrypt(</span><span class="vars">$pue</span><span>); </span></span></li><li class="alt"><span><span class="func">echo</span><span> </span><span class="string">'private decrypt:'</span><span> . </span><span class="vars">$prd</span><span>; </span></span></li><li><span>?> </span></li></ol>对称加密算法
对称加密(也叫私钥加密)指加密和解密使用相同密钥的加密算法。有时又叫传统密码算法，就是加密密钥能够从解密密钥中推算出来，同时解密密钥也可以 从加密密钥中推算出来。而在大多数的对称算法中，加密密钥和解密密钥是相同的，所以也称这种加密算法为秘密密钥算法或单密钥算法。它要求发送方和接收方在 安全通信之前，商定一个密钥。对称算法的安全性依赖于密钥，泄漏密钥就意味着任何人都可以对他们发送或接收的消息解密，所以密钥的保密性对通信性至关重 要。
对称加密的常用算法有: DES算法，3DES算法，TDEA算法，Blowfish算法，RC5算法，IDEA算法。
在PHP中也有封装好的对称加密函数
<ol class="dp-j"><li class="alt"><span><span>Urlencode/Urldecode </span></span></li><li><span> </span></li><li class="alt"><span>string urlencode ( string $str ) </span></li><li><span><span class="comment">/*</span> </span></li><li class="alt"><span><span class="comment">1. 一个参数，传入要加密的字符串通常应用于对URL的加密）</span> </span></li><li><span><span class="comment">2. urlencode为双向加密，可以用urldecode来加密严格意义上来说，不算真正的加密,更像是一种编码方式）</span> </span></li><li class="alt"><span><span class="comment">3. 返回字符串，此字符串中除了 -_. 之外的所有非字母数字字符都将被替换成百分号%）后跟两位十六进制数，空格则编码为加号+）。</span> </span></li><li><span><span class="comment">*/</span><span> </span></span></li></ol>
通过Urlencode函数解决链接中带有&字符引起的问题:
<ol class="dp-j"><li class="alt"><span><span><?php </span></span></li><li><span>$pre_url_encode=<span class="string">"zhougang.com?username=zhougang&password=zhou"</span><span>; </span><span class="comment">//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</span><span> </span></span></li><li class="alt"><span>$url_decode =<span class="string">"zhougang.com?username=zhou&gang&password=zhou"</span><span>;</span><span class="comment">//但是这种情况下用$_GET()来接受是会出问题的;</span><span> </span></span></li><li><span><span class="comment">/*</span> </span></li><li class="alt"><span><span class="comment">Array</span> </span></li><li><span><span class="comment">(</span> </span></li><li class="alt"><span><span class="comment"> [username] => zhou</span> </span></li><li><span><span class="comment"> [gang] =></span> </span></li><li class="alt"><span><span class="comment"> [password] => zhou</span> </span></li><li><span><span class="comment">)</span> </span></li><li class="alt"><span><span class="comment">*/</span><span> </span></span></li><li><span> </span></li><li class="alt"><span><span class="comment">//如下解决问题:</span><span> </span></span></li><li><span>$username=<span class="string">"zhou&gang"</span><span>; </span></span></li><li class="alt"><span>$url_decode=<span class="string">"zhougang.com?username="</span><span>.urlencode($username).</span><span class="string">"&password=zhou"</span><span>; </span></span></li><li><span>?> </span></li><li class="alt"><span> </span></li><li><span>常见的urlencode()的转换字符 </span></li><li class="alt"><span> </span></li><li><span>？=> %3F </span></li><li class="alt"><span>= => %3D </span></li><li><span>% => %<span class="number">25</span><span> </span></span></li><li class="alt"><span>& => %<span class="number">26</span><span> </span></span></li><li><span>\ => %5C </span></li><li class="alt"><span> </span></li><li><span>base64 </span></li><li class="alt"><span> </span></li><li><span>string base64_decode ( string $encoded_data ) </span></li><li class="alt"><span> </span></li><li><span> base64_encode()接受一个参数，也就是要编码的数据这里不说字符串，是因为很多时候base64用来编码图片） </span></li><li class="alt"><span> </span></li><li><span> base64_encode()为双向加密，可用base64_decode()来解密 </span></li><li class="alt"><span> </span></li><li><span>$data=file_get_contents($filename); </span></li><li class="alt"><span>echo base64_encode($data); </span></li><li><span><span class="comment">/*然后你查看网页源码就会得到一大串base64的字符串，</span> </span></li><li class="alt"><span><span class="comment">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）</span> </span></li><li><span><span class="comment">*/</span><span> </span></span></li></ol>
严格的来说..这两个函数其实不算是加密,更像是一种格式的序列化
以下是我们PHP程序中常用到的对称加密算法
discuz经典算法
<ol class="dp-j"><li class="alt"><span><span><?php </span></span></li><li><span>function authcode($string, $operation = <span class="string">'DECODE'</span><span>, $key = </span><span class="string">''</span><span>, $expiry = </span><span class="number">0</span><span>) { </span></span></li><li class="alt"><span> <span class="comment">// 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 </span><span> </span></span></li><li><span> $ckey_length = <span class="number">4</span><span>; </span></span></li><li class="alt"><span> </span></li><li><span> <span class="comment">// 密匙 </span><span> </span></span></li><li class="alt"><span> $key = md5($key ? $key : $GLOBALS[<span class="string">'discuz_auth_key'</span><span>]); </span></span></li><li><span> </span></li><li class="alt"><span> <span class="comment">// 密匙a会参与加解密 </span><span> </span></span></li><li><span> $keya = md5(substr($key, <span class="number">0</span><span>, </span><span class="number">16</span><span>)); </span></span></li><li class="alt"><span> <span class="comment">// 密匙b会用来做数据完整性验证 </span><span> </span></span></li><li><span> $keyb = md5(substr($key, <span class="number">16</span><span>, </span><span class="number">16</span><span>)); </span></span></li><li class="alt"><span> <span class="comment">// 密匙c用于变化生成的密文 </span><span> </span></span></li><li><span> $keyc = $ckey_length ? ($operation == <span class="string">'DECODE'</span><span> ? substr($string, </span><span class="number">0</span><span>, $ckey_length): </span></span></li><li class="alt"><span>substr(md5(microtime()), -$ckey_length)) : <span class="string">''</span><span>; </span></span></li><li><span> <span class="comment">// 参与运算的密匙 </span><span> </span></span></li><li class="alt"><span> $cryptkey = $keya.md5($keya.$keyc); </span></li><li><span> $key_length = strlen($cryptkey); </span></li><li class="alt"><span> <span class="comment">// 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$keyb(密匙b)，</span><span> </span></span></li><li><span><span class="comment">//解密时会通过这个密匙验证数据完整性 </span><span> </span></span></li><li class="alt"><span> <span class="comment">// 如果是解码的话，会从第$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 </span><span> </span></span></li><li><span> $string = $operation == <span class="string">'DECODE'</span><span> ? base64_decode(substr($string, $ckey_length)) : </span></span></li><li class="alt"><span>sprintf(<span class="string">'%010d'</span><span>, $expiry ? $expiry + time() : </span><span class="number">0</span><span>).substr(md5($string.$keyb), </span><span class="number">0</span><span>, </span><span class="number">16</span><span>).$string; </span></span></li><li><span> $string_length = strlen($string); </span></li><li class="alt"><span> $result = <span class="string">''</span><span>; </span></span></li><li><span> $box = range(<span class="number">0</span><span>, </span><span class="number">255</span><span>); </span></span></li><li class="alt"><span> $rndkey = array(); </span></li><li><span> <span class="comment">// 产生密匙簿 </span><span> </span></span></li><li class="alt"><span> <span class="keyword">for</span><span>($i = </span><span class="number">0</span><span>; $i <= </span><span class="number">255</span><span>; $i++) { </span></span></li><li><span> $rndkey[$i] = ord($cryptkey[$i % $key_length]); </span></li><li class="alt"><span> } </span></li><li><span> <span class="comment">// 用固定的算法，打乱密匙簿，增加随机性，好像很复杂，实际上对并不会增加密文的强度 </span><span> </span></span></li><li class="alt"><span> <span class="keyword">for</span><span>($j = $i = </span><span class="number">0</span><span>; $i < </span><span class="number">256</span><span>; $i++) { </span></span></li><li><span> $j = ($j + $box[$i] + $rndkey[$i]) % <span class="number">256</span><span>; </span></span></li><li class="alt"><span> $tmp = $box[$i]; </span></li><li><span> $box[$i] = $box[$j]; </span></li><li class="alt"><span> $box[$j] = $tmp; </span></li><li><span> } </span></li><li class="alt"><span> <span class="comment">// 核心加解密部分 </span><span> </span></span></li><li><span> <span class="keyword">for</span><span>($a = $j = $i = </span><span class="number">0</span><span>; $i < $string_length; $i++) { </span></span></li><li class="alt"><span> $a = ($a + <span class="number">1</span><span>) % </span><span class="number">256</span><span>; </span></span></li><li><span> $j = ($j + $box[$a]) % <span class="number">256</span><span>; </span></span></li><li class="alt"><span> $tmp = $box[$a]; </span></li><li><span> $box[$a] = $box[$j]; </span></li><li class="alt"><span> $box[$j] = $tmp; </span></li><li><span> <span class="comment">// 从密匙簿得出密匙进行异或，再转成字符 </span><span> </span></span></li><li class="alt"><span> $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % <span class="number">256</span><span>])); </span></span></li><li><span> } </span></li><li class="alt"><span> <span class="keyword">if</span><span>($operation == </span><span class="string">'DECODE'</span><span>) { </span></span></li><li><span> <span class="comment">// 验证数据有效性，请看未加密明文的格式 </span><span> </span></span></li><li class="alt"><span> <span class="keyword">if</span><span>((substr($result, </span><span class="number">0</span><span>, </span><span class="number">10</span><span>) == </span><span class="number">0</span><span> || substr($result, </span><span class="number">0</span><span>, </span><span class="number">10</span><span>) - time() > </span><span class="number">0</span><span>) && </span></span></li><li><span>substr($result, <span class="number">10</span><span>, </span><span class="number">16</span><span>) == substr(md5(substr($result, </span><span class="number">26</span><span>).$keyb), </span><span class="number">0</span><span>, </span><span class="number">16</span><span>)) { </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> substr($result, </span><span class="number">26</span><span>); </span></span></li><li><span> } <span class="keyword">else</span><span> { </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> </span><span class="string">''</span><span>; </span></span></li><li><span> } </span></li><li class="alt"><span> } <span class="keyword">else</span><span> { </span></span></li><li><span> <span class="comment">// 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 </span><span> </span></span></li><li class="alt"><span> <span class="comment">// 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 </span><span> </span></span></li><li><span> <span class="keyword">return</span><span> $keyc.str_replace(</span><span class="string">'='</span><span>, </span><span class="string">''</span><span>, base64_encode($result)); </span></span></li><li class="alt"><span> } </span></li><li><span>} </span></li></ol>加解密函数encrypt()
<ol class="dp-j"><li class="alt"><span><span><?php </span></span></li><li><span><span class="comment">//$string：需要加密解密的字符串；$operation：判断是加密还是解密，E表示加密，D表示解密；$key：密匙</span><span> </span></span></li><li class="alt"><span>function encrypt($string,$operation,$key=<span class="string">''</span><span>){ </span></span></li><li><span> $key=md5($key); </span></li><li class="alt"><span> $key_length=strlen($key); </span></li><li><span> $string=$operation==<span class="string">'D'</span><span>?base64_decode($string):substr(md5($string.$key),</span><span class="number">0</span><span>,</span><span class="number">8</span><span>).$string; </span></span></li><li class="alt"><span> $string_length=strlen($string); </span></li><li><span> $rndkey=$box=array(); </span></li><li class="alt"><span> $result=<span class="string">''</span><span>; </span></span></li><li><span> <span class="keyword">for</span><span>($i=</span><span class="number">0</span><span>;$i<=</span><span class="number">255</span><span>;$i++){ </span></span></li><li class="alt"><span> $rndkey[$i]=ord($key[$i%$key_length]); </span></li><li><span> $box[$i]=$i; </span></li><li class="alt"><span> } </span></li><li><span> <span class="keyword">for</span><span>($j=$i=</span><span class="number">0</span><span>;$i<</span><span class="number">256</span><span>;$i++){ </span></span></li><li class="alt"><span> $j=($j+$box[$i]+$rndkey[$i])%<span class="number">256</span><span>; </span></span></li><li><span> $tmp=$box[$i]; </span></li><li class="alt"><span> $box[$i]=$box[$j]; </span></li><li><span> $box[$j]=$tmp; </span></li><li class="alt"><span> } </span></li><li><span> <span class="keyword">for</span><span>($a=$j=$i=</span><span class="number">0</span><span>;$i<$string_length;$i++){ </span></span></li><li class="alt"><span> $a=($a+<span class="number">1</span><span>)%</span><span class="number">256</span><span>; </span></span></li><li><span> $j=($j+$box[$a])%<span class="number">256</span><span>; </span></span></li><li class="alt"><span> $tmp=$box[$a]; </span></li><li><span> $box[$a]=$box[$j]; </span></li><li class="alt"><span> $box[$j]=$tmp; </span></li><li><span> $result.=chr(ord($string[$i])^($box[($box[$a]+$box[$j])%<span class="number">256</span><span>])); </span></span></li><li class="alt"><span> } </span></li><li><span> <span class="keyword">if</span><span>($operation==</span><span class="string">'D'</span><span>){ </span></span></li><li class="alt"><span> <span class="keyword">if</span><span>(substr($result,</span><span class="number">0</span><span>,</span><span class="number">8</span><span>)==substr(md5(substr($result,</span><span class="number">8</span><span>).$key),</span><span class="number">0</span><span>,</span><span class="number">8</span><span>)){ </span></span></li><li><span> <span class="keyword">return</span><span> substr($result,</span><span class="number">8</span><span>); </span></span></li><li class="alt"><span> }<span class="keyword">else</span><span>{ </span></span></li><li><span> <span class="keyword">return</span><span class="string">''</span><span>; </span></span></li><li class="alt"><span> } </span></li><li><span> }<span class="keyword">else</span><span>{ </span></span></li><li class="alt"><span> <span class="keyword">return</span><span> str_replace(</span><span class="string">'='</span><span>,</span><span class="string">''</span><span>,base64_encode($result)); </span></span></li><li><span> } </span></li><li class="alt"><span>} </span></li><li><span>?> </span></li></ol>
