Mac (Java SE 11 & JDK 11 )

java.lang.Object
- javax.crypto.Mac

All Implemented Interfaces:

Cloneable
```
public class Mac
extends Object
implements Cloneable
```
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., SHA256 or SHA384, in combination with a secret shared key. HMAC is specified in RFC 2104.
Every implementation of the Java platform is required to support the following standard Mac algorithms:
- HmacMD5
- HmacSHA1
- HmacSHA256
These algorithms are described in the Mac section of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other algorithms are supported.
Since:

1.4

Constructor Summary

Constructors
Modifier Constructor Description

protected Mac(MacSpi macSpi, Provider provider, String algorithm)
Creates a MAC object.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`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)`	Returns a `Mac` object that implements the specified MAC algorithm.
`static Mac`	`getInstance(String algorithm, String provider)`	Returns a `Mac` object that implements the specified MAC algorithm.
`static Mac`	`getInstance(String algorithm, Provider provider)`	Returns a `Mac` object that implements the specified MAC algorithm.
`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 input)`	Processes `input.remaining()` bytes in the ByteBuffer `input`, starting at `input.position()`.

Methods declared in class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Mac
```
protected Mac(MacSpi macSpi,
              Provider provider,
              String algorithm)
```
    Creates a MAC object.
    
    Parameters:
    
    macSpi - the delegate
    
    provider - the provider
    
    algorithm - the algorithm
- Method Detail
  - getAlgorithm
```
public final String getAlgorithm()
```
    Returns the algorithm name of this Mac object.
    This is the same name that was specified in one of the getInstance calls that created this Mac object.
    
    Returns:
    
    the algorithm name of this Mac object.
  - getInstance
```
public static final Mac getInstance(String algorithm)
                             throws NoSuchAlgorithmException
```
    Returns a Mac object that implements the specified MAC algorithm.
    This method traverses the list of registered security Providers, starting with the most preferred Provider. A new Mac object encapsulating the MacSpi 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