项目中需要加密超长json内容才发现rsa加密长度有限制，于是换一种思路：我们将原本需要加密的内容拆分为多个字符串，一段一段的加密，解密端也是一段一段的解密即可完成。
(1).确认每次加密多少长度
首先我们要知道rsa加密长度是多少，1024位的rsa能加密的长度也是1024位。那么我们一次加密多长的字符串比较好？ 是不是1024/8呢？不是的！因为如果你每次能保证每次要加密的是1024位那就没事这样算是对，但是如果你要加密的字符串不足1024位，不足的部分会用你设置的padding方式去填充这部分内容。那么我们分段加密的长度的公式就是：证书位数/8-padding长度，例如1024的证书配合OPENSSL_PKCS1_PADDING 长度的公式：1024/8-11即可
(2).确认每次解密多少长度
解密不需要考虑填充，所以每次解密大小 = 证书位数/8
(3).我们封装了一个简单的类你可以直接使用，同事(刘平)编写，我整理完善了下。
<?php
class Openssl
{
/**
* 配置信息.
* publicKey => string.
* privateKey => string.
*
* @var mixed
*/
protected $config;
/**
* 初始化.
*
* @param array $config
*/
public function __construct($config)
{
$this->config = $config;
}
/**
* 获取密钥分段加密长度.
*
* @param Closure $keyClosure
*
* @return int
*
* @throws Exception
*/
protected function getEncryptBlockLen($keyClosure)
{
$key_info = openssl_pkey_get_details($keyClosure);
if (!$key_info)
{
throw new Exception('获取密钥信息失败' . openssl_error_string());
}
// bits数除以8 减去padding长度，OPENSSL_PKCS1_PADDING 长度是11
// php openssl 默认填充方式是 OPENSSL_PKCS1_PADDING
return $key_info['bits'] / 8 - 11;
}
/**
* 获取密钥分段解密长度.
*
* @param Closure $keyClosure
*
* @return int
*
* @throws Exception
*/
protected function getDecryptBlockLen($keyClosure)
{
$key_info = openssl_pkey_get_details($keyClosure);
if (!$key_info)
{
throw new Exception('获取密钥信息失败' . openssl_error_string());
}
// bits数除以8得到字符长度
return $key_info['bits'] / 8;
}
/**
* 数据加密.
*
* @param string $text 需要加密的文本
* @param int $type 加密方式:1.公钥加密 2.私钥加密
*
* @return string
*
* @throws Exception
*/
public function encrypt($text, $type)
{
//获取密钥资源
$keyClosure = 1 == $type ? openssl_pkey_get_public($this->config['publicKey']) : openssl_pkey_get_private($this->config['privateKey']);
if (!$keyClosure)
{
throw new Exception('获取密钥失败,请检查密钥是否合法');
}
//RSA进行加密
$encrypt = '';
$plainData = str_split($text, $this->getEncryptBlockLen($keyClosure));
foreach ($plainData as $key => $encrypt_item)
{
$isEncrypted = (1 == $type) ? openssl_public_encrypt($encrypt_item, $encrypted, $keyClosure) : openssl_private_encrypt($encrypt_item, $encrypted, $keyClosure);
if (!$isEncrypted)
{
throw new Exception('加密数据失败,请检查密钥是否合法,' . openssl_error_string());
}
$encrypt .= $encrypted;
}
$encrypt = base64_encode($encrypt);
//返回
return $encrypt;
}
/**
* 数据解密.
*
* @param string $text 需要加密的文本
* @param int $type 加密方式:1.公钥加密 2.私钥加密
*
* @return string
*
* @throws Exception
* @throws
*/
public function decrypt($text, $type)
{
//获取密钥资源
$keyClosure = 1 == $type ? openssl_pkey_get_public($this->config['publicKey']) : openssl_pkey_get_private($this->config['privateKey']);
if (!$keyClosure)
{
throw new Exception('获取密钥失败,请检查密钥是否合法');
}
//RSA进行解密
$data = base64_decode($text);
$data = str_split($data, $this->getDecryptBlockLen($keyClosure));
$decrypt = '';
foreach ($data as $key => $chunk)
{
$isDecrypted = (1 == $type) ? openssl_public_decrypt($chunk, $encrypted, $keyClosure) : openssl_private_decrypt($chunk, $encrypted, $keyClosure);
if (!$isDecrypted)
{
throw new Exception('解密数据失败,请检查密钥是否合法,' . openssl_error_string());
}
$decrypt .= $encrypted;
}
//返回
return $decrypt;
}
}
//01.配置公钥私钥
$config = [
'publicKey' => '-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDAsst/VK6RA+4tFTJtHUTEUY4E
uN/NdXBUc3Lbb9/P+SqvpTI7NCyvl/bSCSXGOeURzIKGffSTe7oKbAITO5GAKbxS
dz8bj8/rb7r9QUwzdvjY6/9x0M3M295GCwrH5ROXv/dGGh4FKcnl31pHuTJmuz4D
HugXS8FNnxlnHwZNLwIDAQAB
-----END PUBLIC KEY-----',
'privateKey' => '-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----',
];
//02.初始化
$openssl = new Openssl($config);
//03.私钥加密->公钥解密,加密5000长度的字符串A
$waitChar = str_repeat('A', 5000);
$privateEnData = $openssl->encrypt($waitChar, 2); //私钥加密
$publicDeData = $openssl->decrypt($privateEnData, 1); //公钥解密
//04.公钥加密->私钥解密,加密10000长度的字符串B
$waitChar = str_repeat('B', 10000);
$publicEnData = $openssl->encrypt($waitChar, 1); //公钥加密
$privateDeData = $openssl->decrypt($publicEnData, 2); //私钥解密
提示：你可以不用关注你的证书大小，因为我们的类已经帮您自动适配了证书大小和分段加密的大小，如果你要修改padding方式记得改掉11
