java.lang.Object javax.crypto.Mac
This class provides the functionality of a "Message Authentication Code" (MAC) algorithm.
A MAC provides a way to check the integrity of information transmitted over or stored in an unreliable medium, based on a secret key. Typically, message authentication codes are used between two parties that share a secret key in order to validate information transmitted between these parties.
A MAC mechanism that is based on cryptographic hash functions is referred to as HMAC. HMAC can be used with any cryptographic hash function, e.g., MD5 or SHA-1, in combination with a secret shared key. HMAC is specified in RFC 2104.
Constructor Summary | |
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protected |
Mac
(
MacSpi
macSpi,
Provider
provider,
String
algorithm) Creates a MAC object. |
Method Summary | |
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Object |
clone
() Returns a clone if the provider implementation is cloneable. |
byte[] |
doFinal
() Finishes the MAC operation. |
byte[] |
doFinal
(byte[] input) Processes the given array of bytes and finishes the MAC operation. |
void |
doFinal
(byte[] output, int outOffset) Finishes the MAC operation. |
String |
getAlgorithm
() Returns the algorithm name of this Mac object. |
static Mac |
getInstance
(
String
algorithm) Generates an Mac object that implements the specified MAC algorithm. |
static Mac |
getInstance
(
String
algorithm,
Provider
provider) Generates an Mac object for the specified MAC algorithm from the specified provider. |
static Mac |
getInstance
(
String
algorithm,
String
provider) Generates an Mac object for the specified MAC algorithm from the specified provider. |
int |
getMacLength
() Returns the length of the MAC in bytes. |
Provider |
getProvider
() Returns the provider of this Mac object. |
void |
init
(
Key
key) Initializes this Mac object with the given key. |
void |
init
(
Key
key,
AlgorithmParameterSpec
params) Initializes this Mac object with the given key and algorithm parameters. |
void |
reset
() Resets this Mac object. |
void |
update
(byte input) Processes the given byte. |
void |
update
(byte[] input) Processes the given array of bytes. |
void |
update
(byte[] input, int offset, int len) Processes the first len bytes in input, starting at offset inclusive. |
void |
update
(
ByteBuffer
Processes input.remaining() bytes in the ByteBuffer input, starting at input.position(). |
Methods inherited from class java.lang. Object |
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equals , finalize , getClass , hashCode , notify , notifyAll , toString , wait , wait , wait |
Constructor Detail |
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protected Mac(MacSpi macSpi, Provider provider, String algorithm)
Method Detail |
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public final String getAlgorithm()
This is the same name that was specified in one of the getInstance calls that created this Mac object.
public static final Mac getInstance(String algorithm) throws NoSuchAlgorithmException
public static final Mac getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
public static final Mac getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
public final Provider getProvider()
public final int getMacLength()
public final void init(Key key) throws InvalidKeyException
public final void init(Key key, AlgorithmParameterSpec params) throws InvalidKeyException, InvalidAlgorithmParameterException
public final void update(byte input) throws IllegalStateException
public final void update(byte[] input) throws IllegalStateException
public final void update(byte[] input, int offset, int len) throws IllegalStateException
public final void update ( ByteBuffer input)
public final byte[] doFinal() throws IllegalStateException
A call to this method resets this Mac object to the state it was in when previously initialized via a call to init(Key) or init(Key, AlgorithmParameterSpec). That is, the object is reset and available to generate another MAC from the same key, if desired, via new calls to update and doFinal. (In order to reuse this Mac object with a different key, it must be reinitialized via a call to init(Key) or init(Key, AlgorithmParameterSpec).
public final void doFinal(byte[] output, int outOffset) throws ShortBufferException, IllegalStateException
A call to this method resets this Mac object to the state it was in when previously initialized via a call to init(Key) or init(Key, AlgorithmParameterSpec). That is, the object is reset and available to generate another MAC from the same key, if desired, via new calls to update and doFinal. (In order to reuse this Mac object with a different key, it must be reinitialized via a call to init(Key) or init(Key, AlgorithmParameterSpec).
The MAC result is stored in output, starting at outOffset inclusive.
public final byte[] doFinal(byte[] input) throws IllegalStateException
A call to this method resets this Mac object to the state it was in when previously initialized via a call to init(Key) or init(Key, AlgorithmParameterSpec). That is, the object is reset and available to generate another MAC from the same key, if desired, via new calls to update and doFinal. (In order to reuse this Mac object with a different key, it must be reinitialized via a call to init(Key) or init(Key, AlgorithmParameterSpec).
public final void reset()
A call to this method resets this Mac object to the state it was in when previously initialized via a call to init(Key) or init(Key, AlgorithmParameterSpec). That is, the object is reset and available to generate another MAC from the same key, if desired, via new calls to update and doFinal. (In order to reuse this Mac object with a different key, it must be reinitialized via a call to init(Key) or init(Key, AlgorithmParameterSpec).
public final Object clone() throws CloneNotSupportedException