SeedDerive
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Utilities;
using Org.BouncyCastle.Utilities;
using System;
namespace Org.BouncyCastle.Pqc.Crypto.Lms
{
public sealed class SeedDerive
{
private readonly byte[] m_I;
private readonly byte[] m_masterSeed;
private readonly IDigest m_digest;
public int J { get; set; }
public int Q { get; set; }
[Obsolete("Use 'GetI' instead")]
public byte[] I {
get {
return m_I;
}
}
[Obsolete("Use 'GetMasterSeed' instead")]
public byte[] MasterSeed {
get {
return m_masterSeed;
}
}
public SeedDerive(byte[] I, byte[] masterSeed, IDigest digest)
{
m_I = I;
m_masterSeed = masterSeed;
m_digest = digest;
}
public byte[] GetI()
{
return Arrays.Clone(m_I);
}
public byte[] GetMasterSeed()
{
return Arrays.Clone(m_masterSeed);
}
public unsafe byte[] DeriveSeed(bool incJ, byte[] target, int offset)
{
if (target.Length - offset < m_digest.GetDigestSize())
throw new ArgumentException("target length is less than digest size.", "target");
int q = Q;
int j = J;
m_digest.BlockUpdate(I, 0, I.Length);
Span<byte> span = new Span<byte>(stackalloc byte[7], 7);
Pack.UInt32_To_BE((uint)q, span);
Pack.UInt16_To_BE((ushort)j, span.Slice(4, span.Length - 4));
span[6] = byte.MaxValue;
m_digest.BlockUpdate(span);
m_digest.BlockUpdate(m_masterSeed, 0, m_masterSeed.Length);
m_digest.DoFinal(target, offset);
if (incJ) {
int num = ++J;
}
return target;
}
}
}