}// end of SHA1
/// <summary>
/// SHA1算法的填充分组方法,将this对象的data按照sha1需要进行分组
/// </summary>
/// <returns>分组后的数据</returns>
private byte[][] SHA1FillGroups()
{
//划定分组
byte[][] groups;
if ((data.Length % (512 / 8)) >= (448 / 8))
{
groups = new byte[data.Length / (512 / 8) + 2][];
}
else
{
groups = new byte[data.Length / (512 / 8) + 1][];
}
// 填充分组
for (int i = 0; i < groups.Length; ++i)
{
groups[i] = new byte[512 / 8];
//填充分组i,当剩余数据不足以填满一个512bit分组时执行else
if (data.Length - i * (512 / 8) >= 512 / 8)
{
Array.Copy(data, 512 / 8 * i, groups[i], 0, 512 / 8);
}
else
{
Array.Copy(data, 512 / 8 * i, groups[i], 0, data.Length - i * (512 / 8));
//原文末尾添加1
groups[i][data.Length - i * (512 / 8)] = 0x80;
//若该分组不够64bit记录原文长度, 则再填充一个分组
if ((data.Length - i * (512 / 8)) >= (448 / 8))
{
groups[++i] = new byte[512 / 8];
}
//最后一个分组的最后8个字节填充数据长度(以bit为单位)
Array.Copy(MyBitConverter.GetBytes(Convert.ToUInt64(data.Length * 8)), 0, groups[i], 512 / 8 - 8, 8);
}
}
return(groups);
}
/// <summary>
/// SHA1算法计算指定分组的w0~w79数据的方法
/// </summary>
/// <param name="group">需要计算的分组</param>
/// <returns>计算得到的w0~w79</returns>
private byte[][] SHA1W0_W79(byte[] group)
{
byte[][] w0_w79 = new byte[80][];
//将输入分组的512bit作为w0_w15
for (int i = 0; i < 16; ++i)
{
w0_w79[i] = new byte[32 / 8];
Array.Copy(group, i * 4, w0_w79[i], 0, 32 / 8);
}
for (int i = 16; i < 80; ++i)
{
//异或求值后循环左移1bit
UInt32 wt =
MyBitConverter.ToUInt32(w0_w79[i - 16]) ^
MyBitConverter.ToUInt32(w0_w79[i - 14]) ^
MyBitConverter.ToUInt32(w0_w79[i - 8]) ^
MyBitConverter.ToUInt32(w0_w79[i - 3]);
wt = (wt << 1) | (wt >> 31);
//对W_t进行赋值
w0_w79[i] = MyBitConverter.GetBytes(wt);
}
return(w0_w79);
}
