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| java.lang.Object
 java.security.KeyFactory
| KeyFactory | | public class KeyFactory (Code) | | 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 bi-directional. 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);
author:
Jan Luehe
version:
1.41, 05/05/07
See Also: Key
See Also: PublicKey
See Also: PrivateKey
See Also: java.security.spec.KeySpec
See Also: java.security.spec.DSAPublicKeySpec
See Also: java.security.spec.X509EncodedKeySpec
since:
1.2 |
| Method Summary | |
| final public PrivateKey | generatePrivate(KeySpec keySpec)
Generates a private key object from the provided key specification
(key material).
Parameters:
keySpec - the specification (key material) of the private key. | | final public PublicKey | generatePublic(KeySpec keySpec)
Generates a public key object from the provided key specification
(key material).
Parameters:
keySpec - the specification (key material) of the public key. | | final public String | getAlgorithm()
Gets the name of the algorithm
associated with this KeyFactory. | | public static KeyFactory | getInstance(String algorithm)
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 Security.getProviders() method.
Parameters:
algorithm - the name of the requested key algorithm. | | public static KeyFactory | getInstance(String algorithm, String provider)
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. | | public static KeyFactory | getInstance(String algorithm, Provider provider)
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
object is returned. | | final public T | getKeySpec(Key key, Class<T> keySpec)
Returns a specification (key material) of the given key object.
keySpec identifies the specification class in which
the key material should be returned. | | final public Provider | getProvider()
Returns the provider of this key factory object. | | final public Key | translateKey(Key key)
Translates a key object, whose provider may be unknown or potentially
untrusted, into a corresponding key object of this key factory.
Parameters:
key - the key whose provider is unknown or untrusted. |
| KeyFactory | | protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider, String algorithm)(Code) | | Creates a KeyFactory object.
Parameters:
keyFacSpi - the delegate
Parameters:
provider - the provider
Parameters:
algorithm - the name of the algorithmto associate with this KeyFactory |
| generatePrivate | | final public PrivateKey generatePrivate(KeySpec keySpec) throws InvalidKeySpecException(Code) | | Generates a private key object from the provided key specification
(key material).
Parameters:
keySpec - the specification (key material) of the private key. the private key.
exception:
InvalidKeySpecException - if the given key specificationis inappropriate for this key factory to produce a private key. |
| generatePublic | | final public PublicKey generatePublic(KeySpec keySpec) throws InvalidKeySpecException(Code) | | Generates a public key object from the provided key specification
(key material).
Parameters:
keySpec - the specification (key material) of the public key. the public key.
exception:
InvalidKeySpecException - if the given key specificationis inappropriate for this key factory to produce a public key. |
| getAlgorithm | | final public String getAlgorithm()(Code) | | Gets the name of the algorithm
associated with this KeyFactory.
the name of the algorithm associated with thisKeyFactory |
| getInstance | | public static KeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException(Code) | | 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 Security.getProviders() method.
Parameters:
algorithm - the name of the requested key algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names. the new KeyFactory object.
exception:
NoSuchAlgorithmException - if no Provider supports aKeyFactorySpi implementation for thespecified algorithm.
See Also: Provider |
| getInstance | | public static KeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException(Code) | | 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
object is returned. Note that the specified Provider object
does not have to be registered in the provider list.
Parameters:
algorithm - the name of the requested key algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
Parameters:
provider - the provider. the new KeyFactory object.
exception:
NoSuchAlgorithmException - if a KeyFactorySpiimplementation for the specified algorithm is not availablefrom the specified Provider object.
exception:
IllegalArgumentException - if the specified provider is null.
See Also: Provider
since:
1.4 |
| getKeySpec | | final public T getKeySpec(Key key, Class<T> keySpec) throws InvalidKeySpecException(Code) | | 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:
key - the key.
Parameters:
keySpec - the specification class in which the key material should be returned. the underlying key specification (key material) in an instanceof the requested specification class.
exception:
InvalidKeySpecException - if the requested key specification isinappropriate for the given key, or the given key cannot be processed(e.g., the given key has an unrecognized algorithm or format). |
| getProvider | | final public Provider getProvider()(Code) | | Returns the provider of this key factory object.
the provider of this key factory object |
| translateKey | | final public Key translateKey(Key key) throws InvalidKeyException(Code) | | Translates a key object, whose provider may be unknown or potentially
untrusted, into a corresponding key object of this key factory.
Parameters:
key - the key whose provider is unknown or untrusted. the translated key.
exception:
InvalidKeyException - if the given key cannot be processedby this key factory. |
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