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

Class XMSSParameters

java.lang.Object

de.hda.fbi.ucs.eucrite.parameters.XMSSParameters

All Implemented Interfaces:

AlgorithmParameters

public class XMSSParameters
extends Object
implements AlgorithmParameters

The parameters required for the XMSS signature scheme. XMSS 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 XMSS 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 one time signature keys use a treeDigest for signing. The available values for treeDigest are defined as static values in this class, e.g. XMSSParameters.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
XMSSParameters(int height, String treeDigest)	Creates a new XMSSParameters object with the given height and treeDigest.

Method Summary

Modifier and Type	Method	Description
int	getHeight()	Returns the height of the Merkle tree.
String	getTreeDigest()	Returns the treeDigest.
AlgorithmParameters.Type	getType()	Return the type of the cryptographic scheme.
static XMSSParameters	XMSSforSmallSignatures()	Use XMSS to prioritize signature size over signing speed.

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

XMSSParameters

public XMSSParameters(int height,
String treeDigest)

Creates a new XMSSParameters object with the given height and treeDigest. XMSS 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 XMSSforSmallSignatures() 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.

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.

XMSSforSmallSignatures

public static XMSSParameters XMSSforSmallSignatures()

Use XMSS to prioritize signature size over signing speed. For this, a height of 20 is used together with SHA256 as tree digest.

If signing speed is more important, you should use XMSSMTParameters.XMSSMTforFastSigning() instead.

Returns:

An XMSSParameters 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 of the Merkle tree.

Returns:

The height of the Merkle tree.