PHP的學習--RSA加密解密

PHP服務端與客戶端交互或者提供開放API時，通常需要對敏感的數據進行加密，這時候rsa非對稱加密就能派上用處了。

舉個通俗易懂的例子，假設我們再登錄一個網站，發送賬號和密碼，請求被攔截了。

密碼沒加密，那攻擊者就直接拿到了密碼，這是最搓的。
密碼加密了，是不可逆加密，那攻擊者只需要模擬那個請求即可登錄。
密碼加密了，是可逆加密，其中攜帶有時間等參數，后臺可以根據時間等參數來判斷是否有效，但因為是在前端加密，其加密方式也能在代碼中找到，找到加密方式就可以得出解密方式。

但是如果我們使用非對稱加密就可以避免以上問題。

非對稱加密算法需要兩個密鑰來進行加密和解密，這兩個秘鑰是公開密鑰（public key，簡稱公鑰）和私有密鑰（private key，簡稱私鑰）。

工作過程如下，甲乙之間使用非對稱加密的方式完成了重要信息的安全傳輸。

非對稱加密工作過程簡要示意圖

乙方生成一對密鑰（公鑰和私鑰）并將公鑰向其它方公開。
得到該公鑰的甲方使用該密鑰對機密信息進行加密后再發送給乙方。
乙方再用自己保存的另一把專用密鑰（私鑰）對加密后的信息進行解密。乙方只能用其專用密鑰（私鑰）解密由對應的公鑰加密后的信息。

在傳輸過程中，即使攻擊者截獲了傳輸的密文，并得到了乙的公鑰，也無法破解密文，因為只有乙的私鑰才能解密密文。
同樣，如果乙要回復加密信息給甲，那么需要甲先公布甲的公鑰給乙用于加密，甲自己保存甲的私鑰用于解密。

在非對稱加密中使用的主要算法有：RSA、Elgamal、背包算法、Rabin、D-H、ECC（橢圓曲線加密算法）等。

下面我們通過一個例子來說明如何用PHP來實現RSA的加密解密。

<?php
class Rsa
{public $privateKey = '';public $publicKey = '';public function __construct(){$resource = openssl_pkey_new();openssl_pkey_export($resource, $this->privateKey);$detail = openssl_pkey_get_details($resource);$this->publicKey = $detail['key'];}public function publicEncrypt($data, $publicKey){openssl_public_encrypt($data, $encrypted, $publicKey);return $encrypted;}public function publicDecrypt($data, $publicKey){openssl_public_decrypt($data, $decrypted, $publicKey);return $decrypted;}public function privateEncrypt($data, $privateKey){openssl_private_encrypt($data, $encrypted, $privateKey);return $encrypted;}public function privateDecrypt($data, $privateKey){openssl_private_decrypt($data, $decrypted, $privateKey);return $decrypted;}
}$rsa = new Rsa();
echo "公鑰：\n", $rsa->publicKey, "\n";
echo "私鑰：\n", $rsa->privateKey, "\n";// 使用公鑰加密
$str = $rsa->publicEncrypt('hello', $rsa->publicKey);
// 這里使用base64是為了不出現亂碼，默認加密出來的值有亂碼
$str = base64_encode($str);
echo "公鑰加密（base64處理過）：\n", $str, "\n";
$str = base64_decode($str);
$pubstr = $rsa->publicDecrypt($str, $rsa->publicKey);
echo "公鑰解密：\n", $pubstr, "\n";
$privstr = $rsa->privateDecrypt($str, $rsa->privateKey);
echo "私鑰解密：\n", $privstr, "\n";// 使用私鑰加密
$str = $rsa->privateEncrypt('world', $rsa->privateKey);
// 這里使用base64是為了不出現亂碼，默認加密出來的值有亂碼
$str = base64_encode($str);
echo "私鑰加密（base64處理過）：\n", $str, "\n";
$str = base64_decode($str);
$pubstr = $rsa->publicDecrypt($str, $rsa->publicKey);
echo "公鑰解密：\n", $pubstr, "\n";
$privstr = $rsa->privateDecrypt($str, $rsa->privateKey);
echo "私鑰解密：\n", $privstr, "\n";

大家執行一下可以看到公鑰加密的數據，只有私鑰能解密，反之亦然，私鑰加密的數據只有公鑰能解碼。

執行結果如下：

這是PHP端的實現，可用在第三方跟平臺之間的數據傳輸，但如果是前端傳到后端該怎么辦呢，搜索了一下，發現了這個庫jsencrypt。

使用jsencrypt加密解密的例子如下：

<!DOCTYPE html>
<html>
<head><title>JSEncrypt Example</title><base id="basetag" href="/jsencrypt-2.3.0/"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><script src="jquery.js"></script><script type="text/javascript" src="bin/jsencrypt.js"></script>
</head>
<body><div class="container"><script type="text/javascript">// Call this code when the page is done loading.$(function() {// Run a quick encryption/decryption when they click.$('#testme').click(function() {// Encrypt with the public key...var encrypt = new JSEncrypt();encrypt.setPublicKey($('#pubkey').val());var encrypted = encrypt.encrypt($('#input').val());console.log(encrypted)// Decrypt with the private key...var decrypt = new JSEncrypt();decrypt.setPrivateKey($('#privkey').val());var uncrypted = decrypt.decrypt(encrypted);console.log(uncrypted)// Now a simple check to see if the round-trip worked.if (uncrypted == $('#input').val()) {alert('It works!!!');} else {alert('Something went wrong....');}});});
</script><label for="privkey">Private Key</label><br/>
<textarea id="privkey" rows="15" cols="65">-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----</textarea><br/>
<label for="pubkey">Public Key</label><br/>
<textarea id="pubkey" rows="15" cols="65">-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA5GkymwBEbyRhNIxrHT11
CNRaTtbg5AZLrkFOC0b9ELsPa/I/n1TZDfa2VVzFezIhjoG/NGdJPc0cWeSljqjJ
0pa6cjt1o4RaQyXkpqmeMCzBcJsa699QI2mw+TZH/XUO0YhCLjOPYNu/jNzhb3SD
3C4Asl55JfBcAXHgbN/EGwl2OTK8JWa9d8lmZ8o+n22xvLeGrQMyem549xWbr8pw
t0JzGlYumJ0yJQTlDh7arf47FEzglpMCqpGYfkWRdn8dyBZEqSQDjIE+aY0p3xCZ
CuROCSR6Gy6P3RTtCexr3vqm/5XyfVKZ2Xu/DdUwL2yYjWaDdtoIW7iAFjOaqiKj
swIDAQAB
-----END PUBLIC KEY-----</textarea><br/>
<label for="input">Text to encrypt:</label><br/>
<textarea id="input" name="input" type="text" rows=4 cols=70>This is a test!</textarea><br/>
<input id="testme" type="button" value="Test Me!!!" /><br/></div>
</body>
</html>

其中的公鑰和私鑰都是上面PHP代碼中生成的，這邊好像只有公鑰加密，私鑰解密。

拿到其中打印出的加密后的數據，嘗試在PHP中進行解密，可以看到也能解密成功。代碼如下：

<?php
class Rsa
{public $privateKey = '-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----';public $publicKey = '-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA5GkymwBEbyRhNIxrHT11
CNRaTtbg5AZLrkFOC0b9ELsPa/I/n1TZDfa2VVzFezIhjoG/NGdJPc0cWeSljqjJ
0pa6cjt1o4RaQyXkpqmeMCzBcJsa699QI2mw+TZH/XUO0YhCLjOPYNu/jNzhb3SD
3C4Asl55JfBcAXHgbN/EGwl2OTK8JWa9d8lmZ8o+n22xvLeGrQMyem549xWbr8pw
t0JzGlYumJ0yJQTlDh7arf47FEzglpMCqpGYfkWRdn8dyBZEqSQDjIE+aY0p3xCZ
CuROCSR6Gy6P3RTtCexr3vqm/5XyfVKZ2Xu/DdUwL2yYjWaDdtoIW7iAFjOaqiKj
swIDAQAB
-----END PUBLIC KEY-----';public function __construct(){}public function publicEncrypt($data, $publicKey){openssl_public_encrypt($data, $encrypted, $publicKey);return $encrypted;}public function publicDecrypt($data, $publicKey){openssl_public_decrypt($data, $decrypted, $publicKey);return $decrypted;}public function privateEncrypt($data, $privateKey){openssl_private_encrypt($data, $encrypted, $privateKey);return $encrypted;}public function privateDecrypt($data, $privateKey){openssl_private_decrypt($data, $decrypted, $privateKey);return $decrypted;}
}$rsa = new Rsa();// 使用公鑰加密的內容
$str = 'IUMBGcLwJECdxUu3LMbeEhGQdoRjCLqFwfZQBO/Odh3tClbq76Tva7yYqTVxexXLmZ3uY8DrOk/XwcVVRr6g9rBnv/zxBxUShCdN0CwkoguvI+6Oju2aUBlM4FhUp+gmasa5YfqylEp1RpsVAp67GMGlxZvp0ekfhFXkjSqAguPd7dKq5YjftP12xOyuJHAzzg7U+eHxffxnneKqXkK7QrfQD6VrLpbYmayPSjMza/RbjXF+d85UeUZUaF25PZ7Y7kD4Yo7/hY/L6peeOkI5//tpl6U4QY9VsFsjAbIpNMsZuNjE/cZ57Kc5WScPsmy0o9wsp5DUEJmu+YYmr6adoA==';
$str = base64_decode($str);
$pubstr = $rsa->publicDecrypt($str, $rsa->publicKey);
echo "公鑰解密：\n", $pubstr, "\n";
$privstr = $rsa->privateDecrypt($str, $rsa->privateKey);
echo "私鑰解密：\n", $privstr, "\n";

解碼結果如下：