/// <summary>
/// Creates a new <see cref="SpongeState"/> specifying its size and rate.
/// </summary>
/// <param name="size">The size of the sponge state.</param>
/// <param name="rate">The rate of the sponge state, i.e. the number of bits which are impacted while absorbing
/// messages.</param>
/// <exception cref="ArgumentException"><paramref name="rate"/> is lower than one, or <paramref name="rate"/> is
/// greater than or equal to <paramref name="size"/>'s <see cref="SpongeSize.B"/>.</exception>
/// <remarks>
/// <para>The capacity of the state, i.e. the number of bits which are not impacted while absorbing messages, will
/// be <paramref name="size"/>.B - <paramref name="rate"/>.</para>
/// </remarks>
public SpongeState(SpongeSize size, int rate)
{
int b = size.B;
if ((rate < 1) || (rate >= b))
{
throw new ArgumentException($"Invalid rate {rate} for width {b}.", nameof(rate));
}
_size = size;
_rate = rate;
_bitstring = Bitstring.Zeroes(b);
}
/// <summary>
/// Creates a new <see cref="SpongeState"/> from an existing bitstring and specified rate.
/// </summary>
/// <param name="bitstring">The bitstring which holds the bits of the sponge state.</param>
/// <param name="rate">The number of bits which are impacted while aborbing messages.</param>
/// <exception cref="ArgumentNullException"><paramref name="bitstring"/> is null.</exception>
/// <exception cref="ArgumentException"><paramref name="bitstring"/> is empty, or <paramref name="rate"/> is lower
/// than one, or <paramref name="rate"/> is greater than or equal to <paramref>
/// <name>size</name>
/// </paramref>
/// 's
/// <see cref="SpongeSize.B"/>.</exception>
/// <remarks>
/// <para>The capacity of the state, i.e. the number of bits which are not impacted while absorbing messages, will
/// be <see cref="bitstring"/>.Length - <paramref name="rate"/>.</para>
/// </remarks>
public SpongeState(Bitstring bitstring, int rate)
{
_bitstring = bitstring ?? throw new ArgumentNullException(nameof(bitstring));
int length = _bitstring.Length;
if (length < 1)
{
throw new ArgumentException("Bitstring cannot be empty.", nameof(bitstring));
}
_size = new SpongeSize(length);
if ((rate < 1) || (rate >= _size.B))
{
throw new ArgumentException($"Invalid rate {rate} for width {_size.B}.", nameof(rate));
}
_rate = rate;
}
/// <summary>
/// Creates a new <see cref="SpongeState"/> from an existing one.
/// </summary>
/// <param name="state">The sponge state to copy.</param>
public SpongeState(SpongeState state)
{
_size = state._size;
_rate = state._rate;
_bitstring = new Bitstring(state._bitstring);
}
/// <summary>
/// Creates a new <see cref="KeccakPermutation"/> specifying its size, rate and number of iterations of a single
/// permutation.
/// </summary>
/// <param name="size">The size of the permutation.</param>
/// <param name="rate">The rate of the permutation.</param>
/// <param name="roundCount">The number of internal iterations of a single permutation.</param>
protected KeccakPermutation(SpongeSize size, int rate, int roundCount)
: base(size, rate)
{
_roundCount = roundCount;
}
/// <summary>
///
/// </summary>
/// <param name="size"></param>
/// <param name="rate"></param>
protected KeccakFunction(SpongeSize size, int rate)
: base(size, rate, 12 + (size.L << 1))
{
}
/// <summary>
/// Creates a new <see cref="SpongeConstruction"/>, specifying the size of the construction and its rate.
/// </summary>
/// <param name="size">The size of the sponge construction.</param>
/// <param name="rate">The rate of the sponge construction.</param>
protected SpongeConstruction(SpongeSize size, int rate)
{
State = new SpongeState(size, rate);
}