求一段.net 转成php 谢谢啦

public static string KeyOrNoKey(string m_Str, string m_key, uint flag)
{
hint outLen = b64_size(m_Str.Length, flag);
StringBuilder Result = new StringBuilder(0xff);
Result.Capacity = outLen;
Result.Length = outLen;
StringBuilder Source = new StringBuilder(m_Str);
b64_des(Source, Result, m_key, m_Str.Length, flag);
string s = Result.ToString().Trim();
return Result.ToString().Trim();
}
以上是.NET 里的代码 有些代码应该是函数内置和程序内的
但我对.net不是很了解，所以想咨询一下怎么样改法 或者能否提供这个.NET 每句的功能注释

我尝试改了一下PHP 大家帮我改改看吧
functionKeyOrNoKey($m_Str,$m_key,$flag)
{
$outLen = b64_size(m_Str.Length, flag);
$StringBuilder= new StringBuilder(0xff);
$Result.Capacity = outLen;
$Result.Length = outLen;
$StringBuilder = new StringBuilder(m_Str);
$b64_des = b64_des(Source, Result, m_key, m_Str.Length, flag);
$string = Result.ToString().Trim();
return Result.ToString().Trim();
}
还是不太懂，希望大家能帮帮我

相关了解……