Class Tree

java.lang.Object

io.crums.util.mrkl.Tree

Direct Known Subclasses:

DeltaTree, FixedLeafTree, FreeLeafTree

public abstract class Tree
extends Object

The Merkle tree. Instances are immutable. This class abstracts away the memory layout for the tree.

See Also:

• Builder
• FixedLeafTree
• FreeLeafTree

Field Summary

Fields

Modifier and Type	Field	Description
static final byte	BRANCH_PAD
static final byte	LEAF_PAD

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Tree(int leaves, String algo)	Base constructor creates an index and locks down the algo.
protected	Tree(Tree copy)	Copy constructor.

Method Summary

Modifier and Type	Method	Description
protected StringBuilder	appendToStringDetail(StringBuilder string)
abstract byte[]	data(int level, int index)	Returns [a copy of] the data for the node at the specified coordinates.
final String	getHashAlgo()	Returns the hashing algorithm that the tree's internal nodes use.
final byte[]	hash()	Returns the hash of the root of the tree.
final int	hashAlgoWidth()	Returns the byte width of the hashing algorithm by observing the width of the node at coordinates (1, 0), which is the first internal node constructed in a tree.
static byte[]	hashInternals(byte[] left, byte[] right, MessageDigest digest)
static byte[]	hashInternals(ByteBuffer left, ByteBuffer right, MessageDigest digest)	Computes and returns the hash of the given merkle nodes.
static byte[]	hashLeaves(byte[] left, byte[] right, MessageDigest digest)
static byte[]	hashLeaves(ByteBuffer left, ByteBuffer right, MessageDigest digest)	Computes and returns the hash of the given leaf nodes.
static byte[]	hashUncommon(byte[] leftInternal, byte[] rightLeaf, MessageDigest digest)	Computes and returns the hash of the given merkle nodes.
static byte[]	hashUncommon(ByteBuffer leftInternal, ByteBuffer rightLeaf, MessageDigest digest)	Computes and returns the hash of the given merkle nodes.
final TreeIndex<Node>	idx()	Returns the random access index into tree structure.
final boolean	isLeafWidthFixed()	Determines whether the width of the leaves is fixed.
final boolean	isOmniWidth()	Determines whether the width of the leaves is the same as the byte width of the hashing algorithm.
abstract int	leafWidth()	Returns the leaf width in bytes if fixed; -1, otherwise (variable).
final Proof	proof(int leafIndex)	Returns a cryptographic path to the root of the Merkle tree.
final Node	root()	Returns the root node of the tree.
String	toString()	For debug use.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

LEAF_PAD

public static final byte LEAF_PAD

See Also:

• Constant Field Values

BRANCH_PAD

public static final byte BRANCH_PAD

See Also:

• Constant Field Values

Constructor Details

Tree

protected Tree(int leaves,
 String algo)

Base constructor creates an index and locks down the algo.

Parameters:

leaves - the number of leaf nodes in the tree

algo - the hash algo used for the trees internal nodes.

Tree

protected Tree(Tree copy)

Copy constructor.

Method Details

hashLeaves

public static byte[] hashLeaves(byte[] left,
 byte[] right,
 MessageDigest digest)

hashLeaves

public static byte[] hashLeaves(ByteBuffer left,
 ByteBuffer right,
 MessageDigest digest)

Computes and returns the hash of the given leaf nodes. On return, the given buffers have no remaining bytes.

hashInternals

public static byte[] hashInternals(byte[] left,
 byte[] right,
 MessageDigest digest)

hashInternals

public static byte[] hashInternals(ByteBuffer left,
 ByteBuffer right,
 MessageDigest digest)

Computes and returns the hash of the given merkle nodes. On return, the given buffers have no remaining bytes.

hashUncommon

public static byte[] hashUncommon(byte[] leftInternal,
 byte[] rightLeaf,
 MessageDigest digest)

Computes and returns the hash of the given merkle nodes.

hashUncommon

public static byte[] hashUncommon(ByteBuffer leftInternal,
 ByteBuffer rightLeaf,
 MessageDigest digest)

Computes and returns the hash of the given merkle nodes. On return, the given buffers have no remaining bytes.

root

public final Node root()

Returns the root node of the tree.

See Also:

• hash()

hash

public final byte[] hash()

Returns the hash of the root of the tree.

getHashAlgo

public final String getHashAlgo()

Returns the hashing algorithm that the tree's internal nodes use. The data for internal nodes (level > 0) is a hash whose value is computed using this algorithm. (The data for leaf nodes can be anything and is independent of this algorithm.)

Returns:

a name compatible with MessageDigest.getInstance(String)

idx

public final TreeIndex<Node> idx()

Returns the random access index into tree structure.

data

public abstract byte[] data(int level,
 int index)

Returns [a copy of] the data for the node at the specified coordinates. For internal nodes, this is just the node's hash, which is computed from the hash of its child nodes; for leaf nodes, the node's data may generally be anything, but more often than not it's the hash of a source object.

See Also:

• Node.data()

leafWidth

public abstract int leafWidth()

Returns the leaf width in bytes if fixed; -1, otherwise (variable).

isLeafWidthFixed

public final boolean isLeafWidthFixed()

Determines whether the width of the leaves is fixed.

Returns:

true iff the leaf width is not variable

isOmniWidth

public final boolean isOmniWidth()

Determines whether the width of the leaves is the same as the byte width of the hashing algorithm.

hashAlgoWidth

public final int hashAlgoWidth()

Returns the byte width of the hashing algorithm by observing the width of the node at coordinates (1, 0), which is the first internal node constructed in a tree.

proof

public final Proof proof(int leafIndex)

Returns a cryptographic path to the root of the Merkle tree.

toString

public String toString()

For debug use.

Overrides:

toString in class Object

appendToStringDetail

protected StringBuilder appendToStringDetail(StringBuilder string)