$mailcont = "邮件正文………超过1024字节………邮件正文";
    $crtpath = "/usr/nc-home/webpost/mailbox/d00/1/y/u/yushuai.niu/.user/certkey/wxd.crt";
    exec("chmod 777 {$crtpath}");
    $fp = fopen($crtpath, "r");
    $crt = fread($fp, 8192);
    fclose($fp);
    $pubKey = openssl_get_publickey($crt);
    //从证书中解析公钥
    $keyData = openssl_pkey_get_details($pubKey);
    $blocks = str_split($mailcont, 1000);
    foreach ($blocks as $block) {
    //公钥加密
    if (!openssl_public_encrypt($block, $chrtext, $keyData['key'])) {
    echo "<br/>" . openssl_error_string() . "<br/>";
    }
    $chrtext .= $chrtext;
    }
    echo "chrtext-->>>$chrtext<br/>";

    $keypath = "/usr/nc-home/webpost/mailbox/d00/1/y/u/yushuai.niu/.user/secretkey/wxd.key";
    exec("chmod 777 {$keypath}");
    $fp = fopen($keypath, "r");
    $key = fread($fp, 8192);
    fclose($fp);
    $cipher = openssl_pkey_get_private($key);
    openssl_private_decrypt($chrtext, $dcyCont, $cipher);
    echo "dcyCont-->>>$dcyCont<br/>";