java.lang.Object
java.security.KeyFactorySpi
net.i2p.crypto.elgamal.KeyFactory
public final class KeyFactoryextends KeyFactorySpi
Java Security Provider KeyFactory implementation for ElGamal public-key cryptosystem.

This class provides the bridge between ElGamal-specific key specifications and the standard Java Cryptography Architecture (JCA) KeyFactory interface. It enables conversion between different key representations and supports standard encoding formats for ElGamal operations within the I2P network.

Supported Operations:

  • Key Generation: Create ElGamal keys from specifications
  • Key Conversion: Translate between different key formats
  • Standard Encoding: Support for PKCS#8 and X.509 formats
  • Key Specification: Extract key parameters from existing keys

Supported Key Specifications:

Usage Example:

// Create KeyFactory instance
KeyFactory keyFactory = KeyFactory.getInstance("ElGamal", "I2P");

// Generate private key from specification
ElGamalParameterSpec params = new ElGamalParameterSpec(p, g);
ElGamalPrivateKeySpec privSpec = new ElGamalPrivateKeySpec(privateKey, params);
ElGamalPrivateKey privateKey = (ElGamalPrivateKey) keyFactory.generatePrivate(privSpec);

// Convert to standard PKCS#8 format
PKCS8EncodedKeySpec pkcs8Spec = keyFactory.getKeySpec(privateKey, PKCS8EncodedKeySpec.class);

Thread Safety: This class is thread-safe and can be used concurrently by multiple threads. Key objects created by this factory are immutable and thread-safe.

Security Considerations:

  • Private key material is handled securely during conversion
  • Standard encoding formats ensure interoperability with other providers
  • ElGamal parameters are validated during key creation
See Also:

  • Constructor Details

    • KeyFactory

      public KeyFactory()
      KeyFactory for ElGamal encryption keys.

  • Method Details

    • engineGeneratePrivate

      protected PrivateKey engineGeneratePrivate(KeySpec keySpec) throws InvalidKeySpecException
      Generates an ElGamal private key from the provided key specification.

      This method converts various key specification formats into ElGamal private keys, supporting both ElGamal-specific specifications and standard PKCS#8 encoding.

      Specified by:
      engineGeneratePrivate in class KeyFactorySpi
      Parameters:
      keySpec - the key specification to convert
      Returns:
      the generated ElGamal private key
      Throws:
      InvalidKeySpecException - if the key specification is unsupported or malformed

    • engineGeneratePublic

      protected PublicKey engineGeneratePublic(KeySpec keySpec) throws InvalidKeySpecException
      Generates an ElGamal public key from the provided key specification.

      This method converts various key specification formats into ElGamal public keys, supporting both ElGamal-specific specifications and standard X.509 encoding.

      Specified by:
      engineGeneratePublic in class KeyFactorySpi
      Parameters:
      keySpec - the key specification to convert
      Returns:
      the generated ElGamal public key
      Throws:
      InvalidKeySpecException - if the key specification is unsupported or malformed

    • engineGetKeySpec

      protected <T extends KeySpec> T engineGetKeySpec(Key key, Class<T> keySpec) throws InvalidKeySpecException
      Returns a specification (key material) of the given key object.

      This method extracts the underlying key parameters from ElGamal keys and converts them into the requested specification format.

      Specified by:
      engineGetKeySpec in class KeyFactorySpi
      Type Parameters:
      T - the type of the returned key specification
      Parameters:
      key - the ElGamal key to extract the parameters from
      keySpec - the requested specification class
      Returns:
      the corresponding key specification
      Throws:
      InvalidKeySpecException - if the requested specification type is unsupported or the key cannot be converted

    • engineTranslateKey

      protected Key engineTranslateKey(Key key) throws InvalidKeyException
      Translates a key object from one provider to another.

      This method would allow conversion between ElGamal keys from different security providers, but currently no other ElGamal providers are known or supported in the I2P environment.

      Specified by:
      engineTranslateKey in class KeyFactorySpi
      Parameters:
      key - the key to translate between providers
      Returns:
      the translated key
      Throws:
      InvalidKeyException - always, as no other ElGamal providers are supported