Class EdDSAParameterSpec

java.lang.Object

org.bouncycastle.jcajce.spec.EdDSAParameterSpec

All Implemented Interfaces:

AlgorithmParameterSpec

public class EdDSAParameterSpec
extends Object
implements AlgorithmParameterSpec

ParameterSpec for EdDSA signature algorithms.

As well as selecting the curve (for key pair generation) the spec can carry the RFC 8032 instance selectors used when signing or verifying: the prehash flag (Ed25519ph / Ed448ph) and an optional context (Ed25519ctx, or the context permitted by Ed448 / the prehash variants). A context, when supplied, must be at most 255 bytes (RFC 8032 sec. 5.1 / 5.2). When neither prehash nor a non-empty context is supplied the spec selects the pure variant, matching BC's historical behaviour for the curve-name-only constructor.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	Ed25519
static final String	Ed448

Constructor Summary

Constructors

Constructor	Description
EdDSAParameterSpec(String curveName)	Base constructor - pure variant, no context.
EdDSAParameterSpec(String curveName, boolean prehash)	Constructor specifying the prehash (Ed25519ph / Ed448ph) selector.
EdDSAParameterSpec(String curveName, boolean prehash, byte[] context)	Constructor specifying the prehash selector and a context.

Method Summary

Modifier and Type	Method	Description
byte[]	getContext()	Return the RFC 8032 context, or null if none was specified.
String	getCurveName()	Return the curve name specified by this parameterSpec.
boolean	isPrehash()	Return whether the prehash (ph) variant is selected.

Methods inherited from class Object

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

Field Details

Ed25519

public static final String Ed25519

See Also:

• Constant Field Values

Ed448

public static final String Ed448

See Also:

• Constant Field Values

Constructor Details

EdDSAParameterSpec

public EdDSAParameterSpec(String curveName)

Base constructor - pure variant, no context.

Parameters:

curveName - name of the curve to specify.

EdDSAParameterSpec

public EdDSAParameterSpec(String curveName,
 boolean prehash)

Constructor specifying the prehash (Ed25519ph / Ed448ph) selector.

Parameters:

curveName - name of the curve to specify.

prehash - true to select the prehash (ph) variant.

EdDSAParameterSpec

public EdDSAParameterSpec(String curveName,
 boolean prehash,
 byte[] context)

Constructor specifying the prehash selector and a context.

Parameters:

curveName - name of the curve to specify.

prehash - true to select the prehash (ph) variant.

context - the RFC 8032 context (at most 255 bytes), or null for none.

Method Details

getCurveName

public String getCurveName()

Return the curve name specified by this parameterSpec.

Returns:

the name of the curve this parameterSpec specifies.

isPrehash

public boolean isPrehash()

Return whether the prehash (ph) variant is selected.

Returns:

true if Ed25519ph / Ed448ph is selected, false for the pure / ctx variant.

getContext

public byte[] getContext()

Return the RFC 8032 context, or null if none was specified.

Returns:

a copy of the context, or null.