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package org.bouncycastle.pqc.crypto.gmss;
import java.util.Vector;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.pqc.crypto.gmss.util.GMSSRandom;
import org.bouncycastle.util.Integers;
import org.bouncycastle.util.encoders.Hex;
/**
* This class implements a treehash instance for the Merkle tree traversal
* algorithm. The first node of the stack is stored in this instance itself,
* additional tail nodes are stored on a tailstack.
*/
public class Treehash
{
/**
* max height of current treehash instance.
*/
private int maxHeight;
/**
* Vector element that stores the nodes on the stack
*/
private Vector tailStack;
/**
* Vector element that stores the height of the nodes on the stack
*/
private Vector heightOfNodes;
/**
* the first node is stored in the treehash instance itself, not on stack
*/
private byte[] firstNode;
/**
* seedActive needed for the actual node
*/
private byte[] seedActive;
/**
* the seed needed for the next re-initialization of the treehash instance
*/
private byte[] seedNext;
/**
* number of nodes stored on the stack and belonging to this treehash
* instance
*/
private int tailLength;
/**
* the height in the tree of the first node stored in treehash
*/
private int firstNodeHeight;
/**
* true if treehash instance was already initialized, false otherwise
*/
private boolean isInitialized;
/**
* true if the first node's height equals the maxHeight of the treehash
*/
private boolean isFinished;
/**
* true if the nextSeed has been initialized with index 3*2^h needed for the
* seed scheduling
*/
private boolean seedInitialized;
/**
* denotes the Message Digest used by the tree to create nodes
*/
private Digest messDigestTree;
/**
* This constructor regenerates a prior treehash object
*
* @param name an array of strings, containing the name of the used hash
* function and PRNG and the name of the corresponding provider
* @param statByte status bytes
* @param statInt status ints
*/
public Treehash(Digest name, byte[][] statByte, int[] statInt)
{
this.messDigestTree = name;
// decode statInt
this.maxHeight = statInt[0];
this.tailLength = statInt[1];
this.firstNodeHeight = statInt[2];
if (statInt[3] == 1)
{
this.isFinished = true;
}
else
{
this.isFinished = false;
}
if (statInt[4] == 1)
{
this.isInitialized = true;
}
else
{
this.isInitialized = false;
}
if (statInt[5] == 1)
{
this.seedInitialized = true;
}
else
{
this.seedInitialized = false;
}
this.heightOfNodes = new Vector();
for (int i = 0; i < tailLength; i++)
{
this.heightOfNodes.addElement(Integers.valueOf(statInt[6 + i]));
}
// decode statByte
this.firstNode = statByte[0];
this.seedActive = statByte[1];
this.seedNext = statByte[2];
this.tailStack = new Vector();
for (int i = 0; i < tailLength; i++)
{
this.tailStack.addElement(statByte[3 + i]);
}
}
/**
* Constructor
*
* @param tailStack a vector element where the stack nodes are stored
* @param maxHeight maximal height of the treehash instance
* @param digest an array of strings, containing the name of the used hash
* function and PRNG and the name of the corresponding provider
*/
public Treehash(Vector tailStack, int maxHeight, Digest digest)
{
this.tailStack = tailStack;
this.maxHeight = maxHeight;
this.firstNode = null;
this.isInitialized = false;
this.isFinished = false;
this.seedInitialized = false;
this.messDigestTree = digest;
this.seedNext = new byte[messDigestTree.getDigestSize()];
this.seedActive = new byte[messDigestTree.getDigestSize()];
}
/**
* Method to initialize the seeds needed for the precomputation of right
* nodes. Should be initialized with index 3*2^i for treehash_i
*
* @param seedIn
*/
public void initializeSeed(byte[] seedIn)
{
System.arraycopy(seedIn, 0, this.seedNext, 0, this.messDigestTree
.getDigestSize());
this.seedInitialized = true;
}
/**
* initializes the treehash instance. The seeds must already have been
* initialized to work correctly.
*/
public void initialize()
{
if (!this.seedInitialized)
{
throw new IllegalStateException("Seed " + this.maxHeight + " not initialized");
}
this.heightOfNodes = new Vector();
this.tailLength = 0;
this.firstNode = null;
this.firstNodeHeight = -1;
this.isInitialized = true;
System.arraycopy(this.seedNext, 0, this.seedActive, 0, messDigestTree
.getDigestSize());
}
/**
* Calculates one update of the treehash instance, i.e. creates a new leaf
* and hashes if possible
*
* @param gmssRandom an instance of the PRNG
* @param leaf The byte value of the leaf needed for the update
*/
public void update(GMSSRandom gmssRandom, byte[] leaf)
{
if (this.isFinished)
{
System.err
.println("No more update possible for treehash instance!");
return;
}
if (!this.isInitialized)
{
System.err
.println("Treehash instance not initialized before update");
return;
}
byte[] help = new byte[this.messDigestTree.getDigestSize()];
int helpHeight = -1;
gmssRandom.nextSeed(this.seedActive);
// if treehash gets first update
if (this.firstNode == null)
{
this.firstNode = leaf;
this.firstNodeHeight = 0;
}
else
{
// store the new node in help array, do not push it on the stack
help = leaf;
helpHeight = 0;
// hash the nodes on the stack if possible
while (this.tailLength > 0
&& helpHeight == ((Integer)heightOfNodes.lastElement())
.intValue())
{
// put top element of the stack and help node in array
// 'tobehashed'
// and hash them together, put result again in help array
byte[] toBeHashed = new byte[this.messDigestTree
.getDigestSize() << 1];
// pop element from stack
System.arraycopy(this.tailStack.lastElement(), 0, toBeHashed,
0, this.messDigestTree.getDigestSize());
this.tailStack.removeElementAt(this.tailStack.size() - 1);
this.heightOfNodes
.removeElementAt(this.heightOfNodes.size() - 1);
System.arraycopy(help, 0, toBeHashed, this.messDigestTree
.getDigestSize(), this.messDigestTree
.getDigestSize());
messDigestTree.update(toBeHashed, 0, toBeHashed.length);
help = new byte[messDigestTree.getDigestSize()];
messDigestTree.doFinal(help, 0);
// increase help height, stack was reduced by one element
helpHeight++;
this.tailLength--;
}
// push the new node on the stack
this.tailStack.addElement(help);
this.heightOfNodes.addElement(Integers.valueOf(helpHeight));
this.tailLength++;
// finally check whether the top node on stack and the first node
// in treehash have same height. If so hash them together
// and store them in treehash
if (((Integer)heightOfNodes.lastElement()).intValue() == this.firstNodeHeight)
{
byte[] toBeHashed = new byte[this.messDigestTree
.getDigestSize() << 1];
System.arraycopy(this.firstNode, 0, toBeHashed, 0,
this.messDigestTree.getDigestSize());
// pop element from tailStack and copy it into help2 array
System.arraycopy(this.tailStack.lastElement(), 0, toBeHashed,
this.messDigestTree.getDigestSize(),
this.messDigestTree.getDigestSize());
this.tailStack.removeElementAt(this.tailStack.size() - 1);
this.heightOfNodes
.removeElementAt(this.heightOfNodes.size() - 1);
// store new element in firstNode, stack is then empty
messDigestTree.update(toBeHashed, 0, toBeHashed.length);
this.firstNode = new byte[messDigestTree.getDigestSize()];
messDigestTree.doFinal(this.firstNode, 0);
this.firstNodeHeight++;
// empty the stack
this.tailLength = 0;
}
}
// check if treehash instance is completed
if (this.firstNodeHeight == this.maxHeight)
{
this.isFinished = true;
}
}
/**
* Destroys a treehash instance after the top node was taken for
* authentication path.
*/
public void destroy()
{
this.isInitialized = false;
this.isFinished = false;
this.firstNode = null;
this.tailLength = 0;
this.firstNodeHeight = -1;
}
/**
* Returns the height of the lowest node stored either in treehash or on the
* stack. It must not be set to infinity (as mentioned in the paper) because
* this cases are considered in the computeAuthPaths method of
* JDKGMSSPrivateKey
*
* @return Height of the lowest node
*/
public int getLowestNodeHeight()
{
if (this.firstNode == null)
{
return this.maxHeight;
}
else if (this.tailLength == 0)
{
return this.firstNodeHeight;
}
else
{
return Math.min(this.firstNodeHeight, ((Integer)heightOfNodes
.lastElement()).intValue());
}
}
/**
* Returns the top node height
*
* @return Height of the first node, the top node
*/
public int getFirstNodeHeight()
{
if (firstNode == null)
{
return maxHeight;
}
return firstNodeHeight;
}
/**
* Method to check whether the instance has been initialized or not
*
* @return true if treehash was already initialized
*/
public boolean wasInitialized()
{
return this.isInitialized;
}
/**
* Method to check whether the instance has been finished or not
*
* @return true if treehash has reached its maximum height
*/
public boolean wasFinished()
{
return this.isFinished;
}
/**
* returns the first node stored in treehash instance itself
*
* @return the first node stored in treehash instance itself
*/
public byte[] getFirstNode()
{
return this.firstNode;
}
/**
* returns the active seed
*
* @return the active seed
*/
public byte[] getSeedActive()
{
return this.seedActive;
}
/**
* This method sets the first node stored in the treehash instance itself
*
* @param hash
*/
public void setFirstNode(byte[] hash)
{
if (!this.isInitialized)
{
this.initialize();
}
this.firstNode = hash;
this.firstNodeHeight = this.maxHeight;
this.isFinished = true;
}
/**
* updates the nextSeed of this treehash instance one step needed for the
* schedulng of the seeds
*
* @param gmssRandom the prng used for the seeds
*/
public void updateNextSeed(GMSSRandom gmssRandom)
{
gmssRandom.nextSeed(seedNext);
}
/**
* Returns the tailstack
*
* @return the tailstack
*/
public Vector getTailStack()
{
return this.tailStack;
}
/**
* Returns the status byte array used by the GMSSPrivateKeyASN.1 class
*
* @return The status bytes
*/
public byte[][] getStatByte()
{
byte[][] statByte = new byte[3 + tailLength][this.messDigestTree
.getDigestSize()];
statByte[0] = firstNode;
statByte[1] = seedActive;
statByte[2] = seedNext;
for (int i = 0; i < tailLength; i++)
{
statByte[3 + i] = (byte[])tailStack.elementAt(i);
}
return statByte;
}
/**
* Returns the status int array used by the GMSSPrivateKeyASN.1 class
*
* @return The status ints
*/
public int[] getStatInt()
{
int[] statInt = new int[6 + tailLength];
statInt[0] = maxHeight;
statInt[1] = tailLength;
statInt[2] = firstNodeHeight;
if (this.isFinished)
{
statInt[3] = 1;
}
else
{
statInt[3] = 0;
}
if (this.isInitialized)
{
statInt[4] = 1;
}
else
{
statInt[4] = 0;
}
if (this.seedInitialized)
{
statInt[5] = 1;
}
else
{
statInt[5] = 0;
}
for (int i = 0; i < tailLength; i++)
{
statInt[6 + i] = ((Integer)heightOfNodes.elementAt(i)).intValue();
}
return statInt;
}
/**
* returns a String representation of the treehash instance
*/
public String toString()
{
String out = "Treehash : ";
for (int i = 0; i < 6 + tailLength; i++)
{
out = out + this.getStatInt()[i] + " ";
}
for (int i = 0; i < 3 + tailLength; i++)
{
if (this.getStatByte()[i] != null)
{
out = out + new String(Hex.encode((this.getStatByte()[i]))) + " ";
}
else
{
out = out + "null ";
}
}
out = out + " " + this.messDigestTree.getDigestSize();
return out;
}
}
