关于c#:C-计算字符串-SHA1

private string SHA1(string str){    byte[] strRes = Encoding.Default.GetBytes(str);    HashAlgorithm iSha = new SHA1CryptoServiceProvider();    strRes = iSha.ComputeHash(strRes);    StringBuilder enText = new StringBuilder();    foreach (byte iByte in strRes)    {        enText.AppendFormat("{0:x2}", iByte);    }    return enText.ToString();}