Package de.hda.fbi.ucs.eucrite.parameters

Class XMSSMTParameters

java.lang.Object

de.hda.fbi.ucs.eucrite.parameters.XMSSMTParameters

All Implemented Interfaces:

AlgorithmParameters

public class XMSSMTParameters
extends Object
implements AlgorithmParameters

The parameters required for the XMSSMT signature scheme. XMSSMT is a stateful signature scheme where the private key needs to be updated after every signature. Multiple usage of the same state will render the scheme insecure. Therefore, the private key should never be copied to prevent multiple usage of a single state.

Another quantum-safe and hash-based, but stateless, signature scheme is SPHINCS.

A XMSSMT private key is a Merkle tree with given height with a one time signature key at every leaf. The number of possible signatures is 2^height. Increasing the height will increase the number of possible signature, but also the size of the private key and the signatures. The tree is divided into subtrees given by the number of layers. The parameters height and layers must be chosen in a way that the reminder of height/layers is zero. The one time signature keys use a treeDigest for signing. The available values for treeDigest are defined as static values in this class, e.g. XMSSMTParameters.SHA512.

Author:

Alexander Zeier

Nested Class Summary

Nested classes/interfaces inherited from interface de.hda.fbi.ucs.eucrite.parameters.AlgorithmParameters

AlgorithmParameters.Algorithm, AlgorithmParameters.Template, AlgorithmParameters.Type

Field Summary

Fields

Modifier and Type	Field	Description
static String	SHA256	Use SHA-256 for the tree generation function.
static String	SHA512	Use SHA512 for the tree generation function.
static String	SHAKE128	Use SHAKE128 for the tree generation function.
static String	SHAKE256	Use SHAKE256 for the tree generation function.

Constructor Summary

Constructors

Constructor	Description
XMSSMTParameters(int height, int layers, String treeDigest)	Creates a new XMSSParameters object with the given height, layers and treeDigest.

Method Summary

Modifier and Type	Method	Description
int	getHeight()	Returns the height.
int	getLayers()	Return the number of layers
String	getTreeDigest()	Returns the treeDigest.
AlgorithmParameters.Type	getType()	Return the type of the cryptographic scheme.
static XMSSMTParameters	XMSSMTforFastSigning()	Use XMSSMT to prioritize signing speed over signature size.

Methods inherited from class java.lang.Object

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

Field Details

SHA256

public static final String SHA256

Use SHA-256 for the tree generation function.

See Also:

Constant Field Values

SHA512

public static final String SHA512

Use SHA512 for the tree generation function.

See Also:

Constant Field Values

SHAKE128

public static final String SHAKE128

Use SHAKE128 for the tree generation function.

See Also:

Constant Field Values

SHAKE256

public static final String SHAKE256

Use SHAKE256 for the tree generation function.

See Also:

Constant Field Values

Constructor Details

XMSSMTParameters

public XMSSMTParameters(int height,
int layers,
String treeDigest)

Creates a new XMSSParameters object with the given height, layers and treeDigest. XMSSMT is a stateful signature scheme where the private key needs to be updated after every signature. Multiple usage of the same state will render the scheme insecure. Therefore, the private key should never be copied to prevent multiple usage of a single state.

Use XMSSMTforFastSigning() to get recommended values for the parameters.

Parameters:

height - The height of the Merkle tree. A higher height results in more doable signatures, but also in a larger private key and signature.

layers - The number of layers. Must divide the height without reminder.

treeDigest - The hash algorithm used for signing.

Method Details

getType

public AlgorithmParameters.Type getType()

Description copied from interface: AlgorithmParameters

Return the type of the cryptographic scheme.

Specified by:

getType in interface AlgorithmParameters

Returns:

The type of the cryptographic scheme.

XMSSMTforFastSigning

public static XMSSMTParameters XMSSMTforFastSigning()

Use XMSSMT to prioritize signing speed over signature size. For this, a height of 20 and 4 layers are used together with SHA256 as tree digest.

If signing speed is more important, you should use XMSSParameters.XMSSforSmallSignatures() instead.

Returns:

An XMSSMTParameters object with predefined values.

getTreeDigest

public String getTreeDigest()

Returns the treeDigest.

Returns:

The hash algorithm used for signing.

getHeight

public int getHeight()

Returns the height.

Returns:

The height of the Merkle tree.

getLayers

public int getLayers()

Return the number of layers

Returns:

The number of layers of Merkle trees.