Class AbstractEncodedPrivateKeyBuilder<S extends AlgorithmKeySpec>

java.lang.Object

zeroecho.core.alg.common.eddsa.AbstractEncodedPrivateKeyBuilder<S>

Type Parameters:

S - the algorithm-specific key specification carrying PKCS#8 data

All Implemented Interfaces:

PrivateKeyImporter<S>

Direct Known Subclasses:

Ed25519PrivateKeyBuilder, Ed448PrivateKeyBuilder

public abstract class AbstractEncodedPrivateKeyBuilder<S extends AlgorithmKeySpec>
extends Object
implements PrivateKeyImporter<S>

Abstract EdDSA Encoded Private Key Builder

Base class for reconstructing EdDSA private keys (e.g., Ed25519, Ed448) from PKCS#8-encoded specifications.

Unlike AbstractEdDSAKeyGenBuilder, which is responsible for generating fresh key pairs, this class focuses on importing existing private keys from their encoded representation. Public key import and key pair generation are deliberately unsupported here.

Responsibilities

• Define jcaKeyFactoryAlg() to specify the canonical JCA algorithm name (e.g., "Ed25519" or "Ed448").
• Define encodedPkcs8(AlgorithmKeySpec) to extract the raw PKCS#8-encoded private key material from the given spec.
• Provide an importPrivate(AlgorithmKeySpec) implementation that rebuilds a PrivateKey using KeyFactory and the PKCS#8-encoded material.

Thread-safety

Stateless and safe for concurrent use. Each import operation creates a new KeyFactory instance internally.

Since:

1.0

Constructor Summary

Constructors

Constructor	Description
AbstractEncodedPrivateKeyBuilder()	Creates a stateless encoded-private-key importer base.

Method Summary

Modifier and Type	Method	Description
protected abstract byte[]	encodedPkcs8(S spec)	Extracts the raw PKCS#8-encoded private key bytes from the given spec.
PrivateKey	importPrivate(S spec)	Imports an EdDSA private key from its PKCS#8-encoded form.
protected abstract String	jcaKeyFactoryAlg()	Returns the canonical JCA algorithm identifier used by KeyFactory.getInstance(String).

Methods inherited from class Object

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

Constructor Details

AbstractEncodedPrivateKeyBuilder

public AbstractEncodedPrivateKeyBuilder()

Creates a stateless encoded-private-key importer base.

Method Details

jcaKeyFactoryAlg

protected abstract String jcaKeyFactoryAlg()

Returns the canonical JCA algorithm identifier used by KeyFactory.getInstance(String).

Must be one of the algorithm names recognized by the JDK (e.g., "Ed25519", "Ed448").

Returns:

the JCA algorithm identifier string

encodedPkcs8

protected abstract byte[] encodedPkcs8(S spec)

Extracts the raw PKCS#8-encoded private key bytes from the given spec.

Subclasses must implement this to pull the encoded material from their AlgorithmKeySpec representation.

Parameters:

spec - algorithm-specific key specification

Returns:

PKCS#8-encoded private key bytes

importPrivate

public PrivateKey importPrivate(S spec)
                         throws GeneralSecurityException

Imports an EdDSA private key from its PKCS#8-encoded form.

This method uses KeyFactory initialized with the algorithm returned by jcaKeyFactoryAlg() to parse the bytes provided by encodedPkcs8(AlgorithmKeySpec).

Specified by:

importPrivate in interface PrivateKeyImporter<S extends AlgorithmKeySpec>

Parameters:

spec - algorithm-specific key specification containing PKCS#8 bytes

Returns:

a reconstructed PrivateKey instance

Throws:

GeneralSecurityException - if the key material is invalid or the JCA provider does not support the algorithm