Detailed explanation of php generating signature and verifying signature

<?php
 　/**
   * 根据原文生成签名内容
   *
   * @param string $data 原文内容
   *
   * @return string
   * @author confu
   */
  function sign($data)
  {
    $filePath = &#39;test.p12&#39;;
    if(!file_exists($filePath)) {
      return false;
    }
 
    $pkcs12 = file_get_contents($filePath);
    if (openssl_pkcs12_read($pkcs12, $certs, &#39;读取证书所需要的密码&#39;)) {
      $privateKey = $certs[&#39;pkey&#39;]; //根据实际情况键值可能不同
      $publicKey = $certs[&#39;cert&#39;];　//根据实际情况键值可能不同
      $binary_signature = "";
      if (openssl_sign($data, $binarySignature, $privateKey, OPENSSL_ALGO_SHA1)) {
        return $binarySignature;
      } else {
        return &#39;&#39;;
      }
    } else {
      return &#39;&#39;;
    }
  }
 
  /**
   * 验证签名自己生成的是否正确
   *
   * @param string $data 签名的原文
   * @param string $signature 签名
   *
   * @return bool
   * @author confu
   */
  function verifySign($data, $signature)
  {
    $filePath = &#39;test.p12&#39;;
    if(!file_exists($filePath)) {
      return false;
    }
 
    $pkcs12 = file_get_contents($filePath);
    if (openssl_pkcs12_read($pkcs12, $certs, &#39;读取证书所需要的密码&#39;)) {
      $publicKey = $certs[&#39;cert&#39;];
      $ok = openssl_verify($data, $signature, $publicKey);
      if ($ok == 1) {
        return true;
      }
    }
    return false;
  }
 
  /**
   * 验证返回的签名是否正确
   *
   * @param string $data　要验证的签名原文
   * @param string $signature 签名内容
   *
   * @return bool
   * @author confu
   */
  function verifyRespondSign($data, $signature)
  {
    $filePath = &#39;allinpay-pds.pem&#39;;
    if(!file_exists($filePath)) {
      return false;
    }
 
    $fp = fopen($filePath, "r");
    $cert = fread($fp, 8192);
    fclose($fp);
    $pubkeyid = openssl_get_publickey($cert);
 
    if(!is_resource($pubkeyid)) {
      return false;
    }
 
    $ok = openssl_verify($data, $signature, $pubkeyid);
    if ($ok == 1) {
      openssl_free_key($pubkeyid);
      return true;
    }
    return false;
  }
?>