Class DhKeyGenBuilder

java.lang.Object

zeroecho.core.alg.dh.DhKeyGenBuilder

All Implemented Interfaces:

AsymmetricKeyPairGenerator<DhSpec>

public final class DhKeyGenBuilder
extends Object
implements AsymmetricKeyPairGenerator<DhSpec>

DH key pair builder

Builds Diffie-Hellman key pairs using the JCA providers available at runtime. This builder targets the JCA algorithm name "DiffieHellman" and accepts a DhSpec describing the desired parameter set.

How it works

• If DhSpec.params() is non-null, those DH parameters are used.
• Otherwise, the builder creates parameters with AlgorithmParameterGenerator for the requested bit length, then initializes a KeyPairGenerator to produce the key pair.

Security note: Prefer named, vetted groups such as the RFC 7919 FFDHE sets exposed by DhSpec (for example DhSpec.ffdhe2048()) over ad-hoc parameter generation.

Thread-safety: Instances are stateless and can be shared across threads.

Example

DhKeyGenBuilder builder = new DhKeyGenBuilder();

// Use a standard FFDHE group
KeyPair kp1 = builder.generateKeyPair(DhSpec.ffdhe2048());

// Or request parameters by size when DhSpec.params() is null
DhSpec sized = DhSpec.ofBits(3072); // example factory returning size-only spec
KeyPair kp2 = builder.generateKeyPair(sized);

Constructor Summary

Constructors

Constructor	Description
DhKeyGenBuilder()	Creates a stateless Diffie-Hellman key-pair generator.

Method Summary

Modifier and Type	Method	Description
KeyPair	generateKeyPair(DhSpec spec)	Generates a Diffie-Hellman key pair for the given specification.

Methods inherited from class Object

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

Constructor Details

DhKeyGenBuilder

public DhKeyGenBuilder()

Creates a stateless Diffie-Hellman key-pair generator.

Method Details

generateKeyPair

public KeyPair generateKeyPair(DhSpec spec)
                        throws GeneralSecurityException

Generates a Diffie-Hellman key pair for the given specification.

If spec.params() is non-null, the contained DHParameterSpec is used directly. Otherwise, parameters are generated with AlgorithmParameterGenerator using spec.sizeBits(), and the resulting parameters are applied to a KeyPairGenerator for "DiffieHellman".

Performance note: On some providers, ad-hoc parameter generation can be slow for large sizes. When possible, pass a DhSpec that supplies a known-good DHParameterSpec.

Example

KeyPair kp = new DhKeyGenBuilder().generateKeyPair(DhSpec.ffdhe3072());

Specified by:

generateKeyPair in interface AsymmetricKeyPairGenerator<DhSpec>

Parameters:

spec - the DH specification indicating either a concrete DHParameterSpec or the target bit length for parameter generation; must not be null

Returns:

a newly generated DH KeyPair

Throws:

GeneralSecurityException - if the JCA provider does not support Diffie-Hellman, parameter generation fails, or key pair generation cannot be completed