// From email with Scott Fluhrer:
// To generate the SEED for a child LMS tree, we will adapt algorithm A by using the
// I value of the parent LMS tree the q value to be the LMS index of the child, and the i value to be 65534.
// Algorithm A:
// x_q[i] = H(I || u32str(q) || u16str(i) || u8str(0xff) || SEED).
// UPDATE: Generate child I from algorithm A using the I value of the parent LMS tree, the q value
// to be the LMS index of the child, and the i value to be 65535; the I value will be the first 128 bits of the hash.
public Hss(int layers, LmsType[] lmsTypes, LmotsType[] lmotsTypes,
EntropyProviderTypes entropyType = EntropyProviderTypes.Random, BitString seed = null, BitString rootI = null)
{
_entropyType = entropyType;
_entropyProvider = _entropyFactory.GetEntropyProvider(entropyType);
_entropyProvider.AddEntropy(seed);
SEED = _entropyProvider.GetEntropy(256); // for now will only be 256 bits (m = 256)
_entropyProvider.AddEntropy(rootI);
RootI = _entropyProvider.GetEntropy(128);
_sha256 = new NativeFastSha2_256();
_lms = new Lms[layers];
_lmsTypes = lmsTypes;
_lmotsTypes = lmotsTypes;
_lms[0] = new Lms(lmsTypes[0], lmotsTypes[0], entropyType, SEED, rootI);
var parentSeed = SEED;
var parentI = RootI;
for (int i = 1; i < layers; i++)
{
var childSeed = _sha256.HashMessage(parentI
.ConcatenateBits(new BitString(0, 32))
.ConcatenateBits(new BitString(65534, 16))
.ConcatenateBits(new BitString("ff", 8))
.ConcatenateBits(parentSeed)).Digest;
var I = _sha256.HashMessage(parentI
.ConcatenateBits(new BitString(0, 32))
.ConcatenateBits(new BitString(65535, 16))
.ConcatenateBits(new BitString("ff", 8))
.ConcatenateBits(parentSeed)).Digest.MSBSubstring(0, 128);
_lms[i] = new Lms(lmsTypes[i], lmotsTypes[i], entropyType, childSeed, I);
parentSeed = childSeed;
parentI = I;
}
}
private const int H25_PIECE_SIZE = 32768; // creates 1024 threads
#endregion Fields
#region Constructors
// From an email from Scott Fluhrer:
// To generate the I value for the LMS tree, we will adapt algorithm A,
// by setting the I value input to be the all-zeros value, the q value
// to be 0 and the i value to be 65535; we will use the first 16 bytes of the hash output.
// Algorithm A:
// x_q[i] = H(I || u32str(q) || u16str(i) || u8str(0xff) || SEED).
// UPDATE: I value is now generated separate from SEED. Child I values still computed the same
public Lms(LmsType lmsType, LmotsType lmotsType,
EntropyProviderTypes entropyType = EntropyProviderTypes.Random, BitString seed = null, BitString I = null)
{
var(m, h, typecode) = LmsModeMapping.GetValsFromType(lmsType);
_m = m;
_h = h;
_typecode = typecode;
var param = LmotsModeMapping.GetValsFromType(lmotsType);
_lmotsTypecode = param.typecode;
_entropyProvider = _entropyFactory.GetEntropyProvider(entropyType);
_entropyProvider.AddEntropy(seed);
SEED = _entropyProvider.GetEntropy(_m * 8);
_entropyProvider.AddEntropy(I);
_I = _entropyProvider.GetEntropy(128);
_lmots = new Lmots(lmotsType, entropyType);
_isRandom = entropyType == EntropyProviderTypes.Random;
_sha256 = new NativeFastSha2_256();
// For optimization the balance between interop calls and asynchronization
if (_h == 5)
{
_pieceSize = H5_PIECE_SIZE;
}
else if (_h == 10)
{
_pieceSize = H10_PIECE_SIZE;
}
else if (_h == 15)
{
_pieceSize = H15_PIECE_SIZE;
}
else if (_h == 20)
{
_pieceSize = H20_PIECE_SIZE;
}
else
{
_pieceSize = H25_PIECE_SIZE;
}
}
public void AddEntropy(BigInteger entropy)
{
_entropyProvider.AddEntropy(entropy);
}
public void AddEntropy(BitString entropy)
{
_entropy.AddEntropy(entropy);
}
