手机短信PDU字符串中用到的7bit加密解密函数

原文参考:http://www.cnblogs.com/Engin/archive/2010/11/07/1871154.html

整理的代码如下:

/// <summary>
/// PDU字符串用到的7bit的加密函数
/// </summary>
/// <param name="len">用户数据长度</param>
/// <param name="strUserData">数据部分PDU字符串</param>
/// <returns></returns>
public string PDU7bitContentEncoder(string strUserData)
{
string result = string.Empty;
string resultLength = strUserData.Length.ToString("X2"); //7bit编码 用户数据长度：源字符串长度

Encoding encodingAsscii = Encoding.ASCII;
byte[] bytes = encodingAsscii.GetBytes(strUserData);

string temp = string.Empty; //存储中间字符串 二进制串
string tmp;
for (int i = strUserData.Length; i > 0; i--) //高低交换 二进制串
{
tmp = Convert.ToString(bytes[i - 1], 2);
while (tmp.Length < 7) //不够7位，补齐
{
tmp = "0" + tmp;
}
temp += tmp;
}

for (int i = temp.Length; i > 0; i -= 8) //每8位取位为一个字符 即完成编码
{
if (i > 8)
{
result += Convert.ToInt32(temp.Substring(i - 8, 8), 2).ToString("X2");
}
else
{
result += Convert.ToInt32(temp.Substring(0, i), 2).ToString("X2");
}
}

return result;
}

/// <summary>
/// PDU字符串用到的7bit的解密函数
/// </summary>
/// <param name="len">用户数据长度</param>
/// <param name="strUserData">数据部分PDU字符串</param>
/// <returns></returns>
public string PDU7bitContentDecoder(string strUserData)
{
string result = string.Empty;
byte[] b;

b = Hex2Bin(strUserData);

Array.Reverse(b); //字节串翻转

result = Bin2BinStringof8Bit(b);

result = BinStringof8Bit2AsciiwithReverse(result);

return result;
}