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浅谈 PHP 中的多种加密技术及代码示例_PHP教程

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2016-07-12 09:06:031288浏览

浅谈 PHP 中的多种加密技术及代码示例

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);

1b4c510fd9f9d72a79ac165bd72a2834359bbbaf.jpg-182.2kB

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>

 



www.bkjia.comtruehttp://www.bkjia.com/PHPjc/1067036.htmlTechArticle浅谈 PHP 中的多种加密技术及代码示例 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...
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