public BitString GetNextIV()
{
if (_iv.BitLength < _blockSize)
{
_iv = BitString.Zeroes(_blockSize - _iv.BitLength).ConcatenateBits(_iv);
}
var currentIV = _iv.GetLeastSignificantBits(_blockSize).GetDeepCopy();
// Avoid throwing an exception by subtracting from 000...0
if (currentIV.Equals(BitString.Zeroes(_blockSize)))
{
_iv = BitString.Ones(_blockSize);
}
else
{
_iv = _iv.BitStringSubtraction(BitString.One());
}
return(currentIV);
}