public class SecretKeyFactory extends Object
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.
Secret key factories operate only on secret (symmetric) keys.
Key factories are bi-directional, i.e., they allow 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.
Application developers should refer to their provider's documentation
to find out which key specifications are supported by the
generateSecret
and
getKeySpec
methods.
For example, the DES secret-key factory supplied by the "SunJCE" provider
supports DESKeySpec
as a transparent representation of DES
keys, and that provider's secret-key factory for Triple DES keys supports
DESedeKeySpec
as a transparent representation of Triple DES
keys.
Every implementation of the Java platform is required to support the
following standard SecretKeyFactory
algorithms:
DES
DESede
SecretKey
,
DESKeySpec
,
DESedeKeySpec
,
PBEKeySpec
Modifier | Constructor and Description |
---|---|
protected |
SecretKeyFactory(SecretKeyFactorySpi keyFacSpi,
Provider provider,
String algorithm)
Creates a SecretKeyFactory object.
|
Modifier and Type | Method and Description |
---|---|
SecretKey |
generateSecret(KeySpec keySpec)
Generates a
SecretKey object from the provided key
specification (key material). |
String |
getAlgorithm()
Returns the algorithm name of this
SecretKeyFactory object. |
static SecretKeyFactory |
getInstance(String algorithm)
Returns a
SecretKeyFactory object that converts
secret keys of the specified algorithm. |
static SecretKeyFactory |
getInstance(String algorithm,
Provider provider)
Returns a
SecretKeyFactory object that converts
secret keys of the specified algorithm. |
static SecretKeyFactory |
getInstance(String algorithm,
String provider)
Returns a
SecretKeyFactory object that converts
secret keys of the specified algorithm. |
KeySpec |
getKeySpec(SecretKey key,
Class<?> keySpec)
Returns a specification (key material) of the given key object
in the requested format.
|
Provider |
getProvider()
Returns the provider of this
SecretKeyFactory object. |
SecretKey |
translateKey(SecretKey key)
Translates a key object, whose provider may be unknown or potentially
untrusted, into a corresponding key object of this secret-key factory.
|
protected SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)
keyFacSpi
- the delegateprovider
- the provideralgorithm
- the secret-key algorithmpublic static final SecretKeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException
SecretKeyFactory
object that converts
secret keys of the specified algorithm.
This method traverses the list of registered security Providers, starting with the most preferred Provider. A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi 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.
algorithm
- the standard name of the requested secret-key
algorithm.
See the SecretKeyFactory section in the
Java Cryptography Architecture Standard Algorithm Name Documentation
for information about standard algorithm names.SecretKeyFactory
object.NullPointerException
- if the specified algorithm
is null.NoSuchAlgorithmException
- if no Provider supports a
SecretKeyFactorySpi implementation for the
specified algorithm.Provider
public static final SecretKeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
SecretKeyFactory
object that converts
secret keys of the specified algorithm.
A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi 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.
algorithm
- the standard name of the requested secret-key
algorithm.
See the SecretKeyFactory section in the
Java Cryptography Architecture Standard Algorithm Name Documentation
for information about standard algorithm names.provider
- the name of the provider.SecretKeyFactory
object.NoSuchAlgorithmException
- if a SecretKeyFactorySpi
implementation for the specified algorithm is not
available from the specified provider.NullPointerException
- if the specified algorithm
is null.NoSuchProviderException
- if the specified provider is not
registered in the security provider list.IllegalArgumentException
- if the provider
is null or empty.Provider
public static final SecretKeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
SecretKeyFactory
object that converts
secret keys of the specified algorithm.
A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
algorithm
- the standard name of the requested secret-key
algorithm.
See the SecretKeyFactory section in the
Java Cryptography Architecture Standard Algorithm Name Documentation
for information about standard algorithm names.provider
- the provider.SecretKeyFactory
object.NullPointerException
- if the specified algorithm
is null.NoSuchAlgorithmException
- if a SecretKeyFactorySpi
implementation for the specified algorithm is not available
from the specified Provider object.IllegalArgumentException
- if the provider
is null.Provider
public final Provider getProvider()
SecretKeyFactory
object.SecretKeyFactory
objectpublic final String getAlgorithm()
SecretKeyFactory
object.
This is the same name that was specified in one of the
getInstance
calls that created this
SecretKeyFactory
object.
SecretKeyFactory
object.public final SecretKey generateSecret(KeySpec keySpec) throws InvalidKeySpecException
SecretKey
object from the provided key
specification (key material).keySpec
- the specification (key material) of the secret keyInvalidKeySpecException
- if the given key specification
is inappropriate for this secret-key factory to produce a secret key.public final KeySpec getKeySpec(SecretKey key, Class<?> keySpec) throws InvalidKeySpecException
key
- the keykeySpec
- the requested format in which the key material shall be
returnedInvalidKeySpecException
- if the requested key specification is
inappropriate for the given key (e.g., the algorithms associated with
key
and keySpec
do not match, or
key
references a key on a cryptographic hardware device
whereas keySpec
is the specification of a software-based
key), or the given key cannot be dealt with
(e.g., the given key has an algorithm or format not supported by this
secret-key factory).public final SecretKey translateKey(SecretKey key) throws InvalidKeyException
key
- the key whose provider is unknown or untrustedInvalidKeyException
- if the given key cannot be processed
by this secret-key factory. Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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