/**
 * RSA私钥加密
 * @param string $private_key 私钥
 * @param string $data 要加密的字符串
 * @return string $encrypted 返回加密后的字符串
 * @author mosishu
 */
function privateEncrypt($private_key,$data){
 $encrypted = '';
 $pi_key = openssl_pkey_get_private($private_key);//这个函数可用来判断私钥是否是可用的，可用返回资源id Resource id
 //最大允许加密长度为117，得分段加密
 $plainData = str_split($data, 100);//生成密钥位数 1024 bit key
 foreach($plainData as $chunk){
  $partialEncrypted = '';
  $encryptionOk = openssl_private_encrypt($chunk,$partialEncrypted,$pi_key);//私钥加密
  if($encryptionOk === false){
   return false;
  }
  $encrypted .= $partialEncrypted;
 }
 
 $encrypted = base64_encode($encrypted);//加密后的内容通常含有特殊字符，需要编码转换下，在网络间通过url传输时要注意base64编码是否是url安全的
 return $encrypted;
}

/**
 * RSA公钥解密(私钥加密的内容通过公钥可以解密出来)
 * @param string $public_key 公钥
 * @param string $data 私钥加密后的字符串
 * @return string $decrypted 返回解密后的字符串
 * @author mosishu
 */
function publicDecrypt($public_key,$data){
 $decrypted = '';
 $pu_key = openssl_pkey_get_public($public_key);//这个函数可用来判断公钥是否是可用的
 $plainData = str_split(base64_decode($data), 128);//生成密钥位数 1024 bit key
 foreach($plainData as $chunk){
  $str = '';
  $decryptionOk = openssl_public_decrypt($chunk,$str,$pu_key);//公钥解密
  if($decryptionOk === false){
   return false;
  }
  $decrypted .= $str;
 }
 return $decrypted;
}

//RSA公钥加密
function publicEncrypt($public_key,$data){
 $encrypted = '';
 $pu_key = openssl_pkey_get_public($public_key);
 $plainData = str_split($data, 100);
 foreach($plainData as $chunk){
  $partialEncrypted = '';
  $encryptionOk = openssl_public_encrypt($chunk,$partialEncrypted,$pu_key);//公钥加密
  if($encryptionOk === false){
   return false;
  }
  $encrypted .= $partialEncrypted;
 }
 $encrypted = base64_encode($encrypted);
 return $encrypted;
}

//RSA私钥解密
function privateDecrypt($private_key,$data){
 $decrypted = '';
 $pi_key = openssl_pkey_get_private($private_key);
 $plainData = str_split(base64_decode($data), 128); 
 foreach($plainData as $chunk){
  $str = '';
  $decryptionOk = openssl_private_decrypt($chunk,$str,$pi_key);//私钥解密
  if($decryptionOk === false){
   return false;
  }
  $decrypted .= $str;
 }
 return $decrypted;
}