OpenJDK 1.23 · java.security.KeyFactory · APIdia, the JavaDoc alternative

Key factories are used to convert keys (opaque cryptographic keys of type Key) into key specifications (transparent representations of the underlying key material), and vice versa.

Key factories are bidirectional. That is, they allow you to build an opaque key object from a given key specification (key material), or to retrieve the underlying key material of a key object in a suitable format.

Multiple compatible key specifications may exist for the same key. For example, a DSA public key may be specified using DSAPublicKeySpec or X509EncodedKeySpec. A key factory can be used to translate between compatible key specifications.

The following is an example of how to use a key factory in order to instantiate a DSA public key from its encoding. Assume Alice has received a digital signature from Bob. Bob also sent her his public key (in encoded format) to verify his signature. Alice then performs the following actions:

X509EncodedKeySpec bobPubKeySpec = new X509EncodedKeySpec(bobEncodedPubKey);
KeyFactory keyFactory = KeyFactory.getInstance("DSA");
PublicKey bobPubKey = keyFactory.generatePublic(bobPubKeySpec);
Signature sig = Signature.getInstance("DSA");
sig.initVerify(bobPubKey);
sig.update(data);
sig.verify(signature);

Every implementation of the Java platform is required to support the following standard KeyFactory algorithms:

DiffieHellman
DSA
RSA

These algorithms are described in the KeyFactory section of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other algorithms are supported.

Field Summary

Modifier and Type	Field and Description
private final String	algorithm
private static final Debug	debug
private final Object	lock
private Provider	provider
private Iterator<Provider.Service>	serviceIterator
private volatile KeyFactorySpi	spi

Constructor Summary

Access	Constructor and Description
protected	KeyFactory(KeyFactorySpi the delegate keyFacSpi, Provider the provider provider, String the name of the algorithm to associate with this `KeyFactory` algorithm) Creates a `KeyFactory` object.
private	KeyFactory(String algorithm)

Method Summary

Modifier and Type	Method and Description
public final PrivateKey	Returns: the private key. generatePrivate(KeySpec the specification (key material) of the private key. keySpec) Generates a private key object from the provided key specification (key material).
public final PublicKey	Returns: the public key. generatePublic(KeySpec the specification (key material) of the public key. keySpec) Generates a public key object from the provided key specification (key material).
public final String	Returns: the name of the algorithm associated with this `KeyFactory` getAlgorithm() Gets the name of the algorithm associated with this `KeyFactory`.
public static KeyFactory	Returns: the new `KeyFactory` object getInstance(String the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. algorithm) Returns a `KeyFactory` object that converts public/private keys of the specified algorithm.
public static KeyFactory	Returns: the new `KeyFactory` object getInstance(String the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. algorithm, String the name of the provider. provider) Returns a `KeyFactory` object that converts public/private keys of the specified algorithm.
public static KeyFactory	Returns: the new `KeyFactory` object getInstance(String the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. algorithm, Provider the provider. provider) Returns a `KeyFactory` object that converts public/private keys of the specified algorithm.
public final < the type of the key specification to be returned T extends KeySpec> T	Returns: the underlying key specification (key material) in an instance of the requested specification class. getKeySpec(Key the key. key, Class<T> the specification class in which the key material should be returned. keySpec) Returns a specification (key material) of the given key object.
public final Provider	Returns: the provider of this key factory object getProvider() Returns the provider of this key factory object.
private KeyFactorySpi	nextSpi(KeyFactorySpi oldSpi) Update the active `KeyFactorySpi` of this class and return the next implementation for failover.
public final Key	Returns: the translated key. translateKey(Key the key whose provider is unknown or untrusted. key) Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this key factory.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

algorithm	back to summary
private final String algorithm

debug	back to summary
private static final Debug debug

lock	back to summary
private final Object lock

provider	back to summary
private Provider provider

serviceIterator	back to summary
private Iterator<Provider.Service> serviceIterator

spi	back to summary
private volatile KeyFactorySpi spi

Constructor Detail

KeyFactory back to summary

KeyFactory	back to summary
protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider, String algorithm) Creates a `KeyFactory` object. Parameters keyFacSpi:KeyFactorySpi the delegate provider:Provider the provider algorithm:String the name of the algorithm to associate with this `KeyFactory`

protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider, String algorithm)

Creates a KeyFactory object.

Parameters

keyFacSpi:KeyFactorySpi: the delegate
provider:Provider: the provider
algorithm:String: the name of the algorithm to associate with this KeyFactory

KeyFactory	back to summary
private KeyFactory(String algorithm) throws NoSuchAlgorithmException

Method Detail

generatePrivate	back to summary
public final PrivateKey generatePrivate(KeySpec keySpec) throws InvalidKeySpecException Generates a private key object from the provided key specification (key material). Parameters keySpec:KeySpec the specification (key material) of the private key. Returns:PrivateKey the private key. Exceptions InvalidKeySpecException: if the given key specification is inappropriate for this key factory to produce a private key.

generatePrivate

back to summary

public final PrivateKey generatePrivate(KeySpec keySpec) throws InvalidKeySpecException

Generates a private key object from the provided key specification (key material).

Parameters

keySpec:KeySpec: the specification (key material) of the private key.

Returns:PrivateKey

the private key.

Exceptions

InvalidKeySpecException:: if the given key specification is inappropriate for this key factory to produce a private key.

generatePublic	back to summary
public final PublicKey generatePublic(KeySpec keySpec) throws InvalidKeySpecException Generates a public key object from the provided key specification (key material). Parameters keySpec:KeySpec the specification (key material) of the public key. Returns:PublicKey the public key. Exceptions InvalidKeySpecException: if the given key specification is inappropriate for this key factory to produce a public key.

generatePublic

back to summary

public final PublicKey generatePublic(KeySpec keySpec) throws InvalidKeySpecException

Generates a public key object from the provided key specification (key material).

Parameters

keySpec:KeySpec: the specification (key material) of the public key.

Returns:PublicKey

the public key.

Exceptions

InvalidKeySpecException:: if the given key specification is inappropriate for this key factory to produce a public key.

getAlgorithm back to summary

getAlgorithm	back to summary
public final String getAlgorithm() Gets the name of the algorithm associated with this `KeyFactory`. Returns:String the name of the algorithm associated with this `KeyFactory`

public final String getAlgorithm()

Gets the name of the algorithm associated with this KeyFactory.

Returns:String: the name of the algorithm associated with this KeyFactory

getInstance back to summary

getInstance	back to summary
public static KeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException Returns a `KeyFactory` object that converts public/private keys of the specified algorithm. This method traverses the list of registered security providers, starting with the most preferred provider. A new `KeyFactory` object encapsulating the `KeyFactorySpi` implementation from the first provider that supports the specified algorithm is returned. Note that the list of registered providers may be retrieved via the `Security.getProviders()` method. Implementation Note The JDK Reference Implementation additionally uses the `jdk.security.provider.preferred` `Security` property to determine the preferred provider order for the specified algorithm. This may be different from the order of providers returned by `Security.getProviders()`. Parameters algorithm:String the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. Returns:KeyFactory the new `KeyFactory` object Exceptions NoSuchAlgorithmException: if no `Provider` supports a `KeyFactorySpi` implementation for the specified algorithm NullPointerException: if `algorithm` is `null` See Also `Provider`

public static KeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException

Returns a KeyFactory object that converts public/private keys of the specified algorithm.

This method traverses the list of registered security providers, starting with the most preferred provider. A new KeyFactory object encapsulating the KeyFactorySpi implementation from the first provider that supports the specified algorithm is returned.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

Implementation Note

The JDK Reference Implementation additionally uses the jdk.security.provider.preferred Security property to determine the preferred provider order for the specified algorithm. This may be different from the order of providers returned by Security.getProviders().

Parameters

algorithm:String: the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.

Returns:KeyFactory

the new KeyFactory object

Exceptions

NoSuchAlgorithmException:: if no Provider supports a KeyFactorySpi implementation for the specified algorithm
NullPointerException:: if algorithm is null

See Also

Provider

getInstance back to summary

getInstance	back to summary
public static KeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException Returns a `KeyFactory` object that converts public/private keys of the specified algorithm. A new `KeyFactory` object encapsulating the `KeyFactorySpi` implementation from the specified provider is returned. The specified provider must be registered in the security provider list. Note that the list of registered providers may be retrieved via the `Security.getProviders()` method. Parameters algorithm:String the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. provider:String the name of the provider. Returns:KeyFactory the new `KeyFactory` object Exceptions NoSuchAlgorithmException: if a `KeyFactorySpi` implementation for the specified algorithm is not available from the specified provider NoSuchProviderException: if the specified provider is not registered in the security provider list IllegalArgumentException: if the provider name is `null` or empty NullPointerException: if `algorithm` is `null` See Also `Provider`

public static KeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException

Returns a KeyFactory object that converts public/private keys of the specified algorithm.

A new KeyFactory object encapsulating the KeyFactorySpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

Parameters

algorithm:String: the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
provider:String: the name of the provider.

Returns:KeyFactory

the new KeyFactory object

Exceptions

NoSuchAlgorithmException:: if a KeyFactorySpi implementation for the specified algorithm is not available from the specified provider
NoSuchProviderException:: if the specified provider is not registered in the security provider list
IllegalArgumentException:: if the provider name is null or empty
NullPointerException:: if algorithm is null

See Also

Provider

getInstance back to summary

getInstance	back to summary
public static KeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException Returns a `KeyFactory` object that converts public/private keys of the specified algorithm. A new `KeyFactory` object encapsulating the `KeyFactorySpi` implementation from the specified provider is returned. Note that the specified provider does not have to be registered in the provider list. Parameters algorithm:String the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. provider:Provider the provider. Returns:KeyFactory the new `KeyFactory` object Exceptions NoSuchAlgorithmException: if a `KeyFactorySpi` implementation for the specified algorithm is not available from the specified `Provider` object IllegalArgumentException: if the specified provider is `null` NullPointerException: if `algorithm` is `null` Since 1.4 See Also `Provider`

public static KeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException

Returns a KeyFactory object that converts public/private keys of the specified algorithm.

A new KeyFactory object encapsulating the KeyFactorySpi implementation from the specified provider is returned. Note that the specified provider does not have to be registered in the provider list.

Parameters

algorithm:String: the name of the requested key algorithm. See the KeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
provider:Provider: the provider.

Returns:KeyFactory

the new KeyFactory object

Exceptions

NoSuchAlgorithmException:: if a KeyFactorySpi implementation for the specified algorithm is not available from the specified Provider object
IllegalArgumentException:: if the specified provider is null
NullPointerException:: if algorithm is null

Since

1.4

See Also

Provider

getKeySpec back to summary

getKeySpec	back to summary
public final <T extends KeySpec> T getKeySpec(Key key, Class<T> keySpec) throws InvalidKeySpecException Returns a specification (key material) of the given key object. `keySpec` identifies the specification class in which the key material should be returned. It could, for example, be `DSAPublicKeySpec.class`, to indicate that the key material should be returned in an instance of the `DSAPublicKeySpec` class. Parameters <T> the type of the key specification to be returned key:Key the key. keySpec:Class<T> the specification class in which the key material should be returned. Returns:T the underlying key specification (key material) in an instance of the requested specification class. Exceptions InvalidKeySpecException: if the requested key specification is inappropriate for the given key, or the given key cannot be processed (e.g., the given key has an unrecognized algorithm or format).

public final <T extends KeySpec> T getKeySpec(Key key, Class<T> keySpec) throws InvalidKeySpecException

Returns a specification (key material) of the given key object. keySpec identifies the specification class in which the key material should be returned. It could, for example, be DSAPublicKeySpec.class, to indicate that the key material should be returned in an instance of the DSAPublicKeySpec class.

Parameters

<T>: the type of the key specification to be returned
key:Key: the key.
keySpec:Class<T>: the specification class in which the key material should be returned.

Returns:T

the underlying key specification (key material) in an instance of the requested specification class.

Exceptions

InvalidKeySpecException:: if the requested key specification is inappropriate for the given key, or the given key cannot be processed (e.g., the given key has an unrecognized algorithm or format).

getProvider	back to summary
public final Provider getProvider() Returns the provider of this key factory object. Returns:Provider the provider of this key factory object

getProvider

back to summary

public final Provider getProvider()

Returns the provider of this key factory object.

Returns:Provider: the provider of this key factory object

nextSpi	back to summary
private KeyFactorySpi nextSpi(KeyFactorySpi oldSpi) Update the active `KeyFactorySpi` of this class and return the next implementation for failover. If no more implementations are available, this method returns null. However, the active spi of this class is never set to `null`.

translateKey	back to summary
public final Key translateKey(Key key) throws InvalidKeyException Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this key factory. Parameters key:Key the key whose provider is unknown or untrusted. Returns:Key the translated key. Exceptions InvalidKeyException: if the given key cannot be processed by this key factory.

translateKey

back to summary

public final Key translateKey(Key key) throws InvalidKeyException

Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this key factory.

Parameters

key:Key: the key whose provider is unknown or untrusted.

Returns:Key

the translated key.

Exceptions

InvalidKeyException:: if the given key cannot be processed by this key factory.

public Class KeyFactory

Field Summary

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Field Detail

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