/**
* add the pad bytes to the passed in block, returning the
* number of bytes added.
*/
public int AddPadding(
byte[] input,
int inOff)
{
var code = (byte)(input.Length - inOff);
while (inOff < (input.Length - 1))
{
input[inOff] = (byte)_random.NextInt();
inOff++;
}
input[inOff] = code;
return(code);
}
private byte[] EncodeBlock(byte[] input, int inOff, int inLen)
{
if (inLen > GetInputBlockSize())
{
throw new ArgumentException(@"input data too large", "inLen");
}
var block = new byte[_engine.GetInputBlockSize()];
if (_forPrivateKey)
{
block[0] = 0x01; // type code 1
for (var i = 1; i != block.Length - inLen - 1; i++)
{
block[i] = (byte)0xFF;
}
}
else
{
_random.NextBytes(block); // random fill
block[0] = 0x02; // type code 2
//
// a zero byte marks the end of the padding, so all
// the pad bytes must be non-zero.
//
for (var i = 1; i != block.Length - inLen - 1; i++)
{
while (block[i] == 0)
{
block[i] = (byte)_random.NextInt();
}
}
}
block[block.Length - inLen - 1] = 0x00; // mark the end of the padding
Array.Copy(input, inOff, block, block.Length - inLen, inLen);
return(_engine.ProcessBlock(block, 0, block.Length));
}
