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Added in API level 1

Summary: Protected Ctors | Methods | Inherited Methods | [Expand All]

Mac

public class Mac
extends Object implements Cloneable

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.

Android provides the following Mac algorithms

Name	Supported (API Levels)
DESedeMAC	1–8
DESedeMAC/CFB8	1–8
DESedeMAC64	1–8
DESMAC	1–8
DESMAC/CFB8	1–8
DESwithISO9797	1–8
HmacMD5	1+
HmacSHA1	1+
HmacSHA224	1–8, 22+
HmacSHA256	1+
HmacSHA384	1+
HmacSHA512	1+
ISO9797ALG3MAC	1–8
PBEwithHmacSHA	1+
PBEwithHmacSHA1	1+

These algorithms are described in the Mac section of the Java Cryptography Architecture Standard Algorithm Name Documentation.

Summary

Protected constructors
`Mac(MacSpi macSpi, Provider provider, String algorithm)` Creates a MAC object.

Public methods
`final Object`	`clone()` Returns a clone if the provider implementation is cloneable.
`final byte[]`	`doFinal(byte[] input)` Processes the given array of bytes and finishes the MAC operation.
`final void`	`doFinal(byte[] output, int outOffset)` Finishes the MAC operation.
`final byte[]`	`doFinal()` Finishes the MAC operation.
`final String`	`getAlgorithm()` Returns the algorithm name of this `Mac` object.
`static final Mac`	`getInstance(String algorithm)` Returns a `Mac` object that implements the specified MAC algorithm.
`static final Mac`	`getInstance(String algorithm, String provider)` Returns a `Mac` object that implements the specified MAC algorithm.
`static final Mac`	`getInstance(String algorithm, Provider provider)` Returns a `Mac` object that implements the specified MAC algorithm.
`final int`	`getMacLength()` Returns the length of the MAC in bytes.
`final Provider`	`getProvider()` Returns the provider of this `Mac` object.
`final void`	`init(Key key, AlgorithmParameterSpec params)` Initializes this `Mac` object with the given key and algorithm parameters.
`final void`	`init(Key key)` Initializes this `Mac` object with the given key.
`final void`	`reset()` Resets this `Mac` object.
`final void`	`update(byte[] input)` Processes the given array of bytes.
`final void`	`update(byte[] input, int offset, int len)` Processes the first `len` bytes in `input`, starting at `offset` inclusive.
`final void`	`update(ByteBuffer input)` Processes `input.remaining()` bytes in the ByteBuffer `input`, starting at `input.position()`.
`final void`	`update(byte input)` Processes the given byte.

Inherited methods

From class


  
    java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long millis, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void`	`wait(long millis)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void`	`wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

Protected constructors

Mac

Added in API level 1

Mac (MacSpi macSpi, 
                Provider provider, 
                String algorithm)

Creates a MAC object.

Parameters
`macSpi`	`MacSpi`: the delegate
`provider`	`Provider`: the provider
`algorithm`	`String`: the algorithm

Public methods

clone

Added in API level 1

Object clone ()

Returns a clone if the provider implementation is cloneable.

Returns
`Object`	a clone if the provider implementation is cloneable.

Throws
`CloneNotSupportedException`	if this is called on a delegate that does not support `Cloneable`.

doFinal

Added in API level 1

byte[] doFinal (byte[] input)

Processes the given array of bytes and finishes the MAC operation.

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).

Parameters
`input`	`byte`: data in bytes

Returns
`byte[]`	the MAC result.

Throws
`IllegalStateException`	if this `Mac` has not been initialized.

doFinal

Added in API level 1

void doFinal (byte[] output, 
                int outOffset)

Finishes the MAC operation.

The MAC result is stored in output, starting at outOffset inclusive.

Parameters
`output`	`byte`: the buffer where the MAC result is stored
`outOffset`	`int`: the offset in `output` where the MAC is stored

Throws
`ShortBufferException`	if the given output buffer is too small to hold the result
`IllegalStateException`	if this `Mac` has not been initialized.

doFinal

Added in API level 1

byte[] doFinal ()

Finishes the MAC operation.

Returns
`byte[]`	the MAC result.

Throws
`IllegalStateException`	if this `Mac` has not been initialized.

getAlgorithm

Added in API level 1

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
`String`	the algorithm name of this `Mac` object.

getInstance

Added in API level 1

Mac getInstance (String algorithm)

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.

Parameters
`algorithm`	`String`: the standard name of the requested MAC algorithm. See the Mac section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.

Returns
`Mac`	the new `Mac` object.

Throws
`NoSuchAlgorithmException`	if no Provider supports a MacSpi implementation for the specified algorithm.

See also:

Provider

getInstance

Added in API level 1

Mac getInstance (String algorithm, 
                String provider)

Returns a Mac object that implements the specified MAC algorithm.

A new Mac object encapsulating the MacSpi 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`	`String`: the standard name of the requested MAC algorithm. See the Mac section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.
`provider`	`String`: the name of the provider.

Returns
`Mac`	the new `Mac` object.

Throws
`NoSuchAlgorithmException`	if a MacSpi 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.
`IllegalArgumentException`	if the `provider` is null or empty.

See also:

Provider

getInstance

Added in API level 1

Mac getInstance (String algorithm, 
                Provider provider)

Returns a Mac object that implements the specified MAC algorithm.

A new Mac object encapsulating the MacSpi 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`	`String`: the standard name of the requested MAC algorithm. See the Mac section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.
`provider`	`Provider`: the provider.

Returns
`Mac`	the new `Mac` object.

Throws
`NoSuchAlgorithmException`	if a MacSpi implementation for the specified algorithm is not available from the specified Provider object.
`IllegalArgumentException`	if the `provider` is null.

See also:

Provider

getMacLength

Added in API level 1

int getMacLength ()

Returns the length of the MAC in bytes.

Returns
`int`	the MAC length in bytes.

getProvider

Added in API level 1

Provider getProvider ()

Returns the provider of this Mac object.

Returns
`Provider`	the provider of this `Mac` object.

init

Added in API level 1

void init (Key key, 
                AlgorithmParameterSpec params)

Initializes this Mac object with the given key and algorithm parameters.

Parameters
`key`	`Key`: the key.
`params`	`AlgorithmParameterSpec`: the algorithm parameters.

Throws
`InvalidKeyException`	if the given key is inappropriate for initializing this MAC.
`InvalidAlgorithmParameterException`	if the given algorithm parameters are inappropriate for this MAC.

init

Added in API level 1

void init (Key key)

Initializes this Mac object with the given key.

Parameters
`key`	`Key`: the key.

Throws
`InvalidKeyException`	if the given key is inappropriate for initializing this MAC.

reset

Added in API level 1

void reset ()

Resets this Mac object.

update

Added in API level 1

void update (byte[] input)

Processes the given array of bytes.

Parameters
`input`	`byte`: the array of bytes to be processed.

Throws
`IllegalStateException`	if this `Mac` has not been initialized.

update

Added in API level 1

void update (byte[] input, 
                int offset, 
                int len)

Processes the first len bytes in input, starting at offset inclusive.

Parameters
`input`	`byte`: the input buffer.
`offset`	`int`: the offset in `input` where the input starts.
`len`	`int`: the number of bytes to process.

Throws
`IllegalStateException`	if this `Mac` has not been initialized.

update

Added in API level 1

void update (ByteBuffer input)

Processes input.remaining() bytes in the ByteBuffer input, starting at input.position(). Upon return, the buffer's position will be equal to its limit; its limit will not have changed.

Parameters
`input`	`ByteBuffer`: the ByteBuffer

Throws
`IllegalStateException`	if this `Mac` has not been initialized.

update

Added in API level 1

void update (byte input)

Processes the given byte.

Parameters
`input`	`byte`: the input byte to be processed.

Throws
`IllegalStateException`	if this `Mac` has not been initialized.

Interfaces

Classes

Exceptions

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Protected constructors

Mac

Public methods

clone

doFinal

doFinal

doFinal

getAlgorithm

getInstance

getInstance

getInstance

getMacLength

getProvider

init

init

reset

update

update

update

update