Class SecretKeyFactory
- java.lang.Object
-
- javax.crypto.SecretKeyFactory
public class SecretKeyFactory extends Object
This class represents a factory for secret keys.
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
- Since:
- 1.4
- See Also:
-
SecretKey
,DESKeySpec
,DESedeKeySpec
,PBEKeySpec
Constructor Summary
Modifier | Constructor | Description |
---|---|---|
protected | SecretKeyFactory(SecretKeyFactorySpi keyFacSpi,
Provider provider,
String algorithm) | Creates a SecretKeyFactory object. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
SecretKey | generateSecret(KeySpec keySpec) | Generates a |
String | getAlgorithm() | Returns the algorithm name of this |
static SecretKeyFactory | getInstance(String algorithm) | Returns a |
static SecretKeyFactory | getInstance(String algorithm,
String provider) | Returns a |
static SecretKeyFactory | getInstance(String algorithm,
Provider provider) | Returns a |
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 |
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. |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
SecretKeyFactory
protected SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)
Creates a SecretKeyFactory object.
- Parameters:
-
keyFacSpi
- the delegate -
provider
- the provider -
algorithm
- the secret-key algorithm
Method Detail
getInstance
public static final SecretKeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException
Returns a 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.
- 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 than the order of providers returned bySecurity.getProviders()
. - Parameters:
-
algorithm
- the standard name of the requested secret-key algorithm. See the SecretKeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. - Returns:
- the new
SecretKeyFactory
object - Throws:
-
NoSuchAlgorithmException
- if noProvider
supports aSecretKeyFactorySpi
implementation for the specified algorithm -
NullPointerException
- ifalgorithm
isnull
- See Also:
Provider
getInstance
public static final SecretKeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
Returns a 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.
- Parameters:
-
algorithm
- the standard name of the requested secret-key algorithm. See the SecretKeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. -
provider
- the name of the provider. - Returns:
- the new
SecretKeyFactory
object - Throws:
-
IllegalArgumentException
- if theprovider
isnull
or empty -
NoSuchAlgorithmException
- if aSecretKeyFactorySpi
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 -
NullPointerException
- ifalgorithm
isnull
- See Also:
Provider
getInstance
public static final SecretKeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
Returns a 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.
- Parameters:
-
algorithm
- the standard name of the requested secret-key algorithm. See the SecretKeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. -
provider
- the provider. - Returns:
- the new
SecretKeyFactory
object - Throws:
-
IllegalArgumentException
- if theprovider
isnull
-
NoSuchAlgorithmException
- if aSecretKeyFactorySpi
implementation for the specified algorithm is not available from the specifiedProvider
object -
NullPointerException
- ifalgorithm
isnull
- See Also:
Provider
getProvider
public final Provider getProvider()
Returns the provider of this SecretKeyFactory
object.
- Returns:
- the provider of this
SecretKeyFactory
object
getAlgorithm
public final String getAlgorithm()
Returns the algorithm name of this SecretKeyFactory
object.
This is the same name that was specified in one of the getInstance
calls that created this SecretKeyFactory
object.
- Returns:
- the algorithm name of this
SecretKeyFactory
object.
generateSecret
public final SecretKey generateSecret(KeySpec keySpec) throws InvalidKeySpecException
Generates a SecretKey
object from the provided key specification (key material).
- Parameters:
-
keySpec
- the specification (key material) of the secret key - Returns:
- the secret key
- Throws:
-
InvalidKeySpecException
- if the given key specification is inappropriate for this secret-key factory to produce a secret key.
getKeySpec
public final KeySpec getKeySpec(SecretKey key, Class<?> keySpec) throws InvalidKeySpecException
Returns a specification (key material) of the given key object in the requested format.
- Parameters:
-
key
- the key -
keySpec
- the requested format in which the key material shall be returned - Returns:
- the underlying key specification (key material) in the requested format
- Throws:
-
InvalidKeySpecException
- if the requested key specification is inappropriate for the given key (e.g., the algorithms associated withkey
andkeySpec
do not match, orkey
references a key on a cryptographic hardware device whereaskeySpec
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).
translateKey
public final SecretKey translateKey(SecretKey key) throws InvalidKeyException
Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this secret-key factory.
- Parameters:
-
key
- the key whose provider is unknown or untrusted - Returns:
- the translated key
- Throws:
-
InvalidKeyException
- if the given key cannot be processed by this secret-key factory.