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java.lang.Object | +----java.security.KeyFactory
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);
Constructor Summary | |
KeyFactory(KeyFactorySpi keyFacSpi,
Provider provider,
String algorithm)
|
Method Summary | |
PrivateKey | generatePrivate(KeySpec keySpec)
|
PublicKey | generatePublic(KeySpec keySpec)
|
String | getAlgorithm()
|
static KeyFactory | getInstance(String algorithm)
|
static KeyFactory | getInstance(String algorithm,
String provider)
|
KeySpec | getKeySpec(Key key,
Class keySpec)
|
Provider | getProvider()
|
Key | translateKey(Key key)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider, String algorithm)
keyFacSpi
- the delegate
provider
- the provider
Method Detail |
public static final KeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException
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.
public static final KeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
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.
provider
- the name of the provider.
public final Provider getProvider()
public final String getAlgorithm()
public final PublicKey generatePublic(KeySpec keySpec) throws InvalidKeySpecException
keySpec
- the specification (key material) of the public key.
public final PrivateKey generatePrivate(KeySpec keySpec) throws InvalidKeySpecException
keySpec
- the specification (key material) of the private key.
public final KeySpec getKeySpec(Key key, Class keySpec) throws InvalidKeySpecException
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.
key
- the key.
keySpec
- the specification class in which
the key material should be returned.
public final Key translateKey(Key key) throws InvalidKeyException
key
- the key whose provider is unknown or untrusted.
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