com.absio.crypto.mac

Class MacHelper

java.lang.Object

com.absio.crypto.mac.MacHelper

public class MacHelper
extends Object

This is a helper class for dealing with Keyed-Hash Message Authentication Codes (HMAC) operations. This helper will operate using a single algorithm that is passed in the constructor. By default it will use MacAlgorithm.DEFAULT (HMACSHA384). Under the hood the Mac class is used.

Constructor Summary

Constructors

Constructor and Description
MacHelper() Default constructor that creates a helper that uses MacAlgorithm.DEFAULT (HMACSHA384).
MacHelper(MacAlgorithm algorithm) Constructor that creates a helper that uses the provided algorithm.

Method Summary

Modifier and Type	Method and Description
byte[]	digest(SecretKey key, byte[] data) Creates the message digest using the helpers algorithm for the given data using the given key.
SecretKey	generateKey() This generates a new SecretKey using the helpers MacAlgorithm.
SecretKey	generateKey(byte[] encodedKey) This generates a SecretKey from the given key bytes using the helpers MacAlgorithm.
boolean	verify(SecretKey key, byte[] data, byte[] digest) This will check to see if the passed in digest matches the digest created from the passed in key and data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MacHelper

public MacHelper()
          throws NoSuchAlgorithmException

Default constructor that creates a helper that uses MacAlgorithm.DEFAULT (HMACSHA384).

Throws:

NoSuchAlgorithmException - thrown if the HMACSHA384 algorithm is not supported

MacHelper

public MacHelper(MacAlgorithm algorithm)
          throws NoSuchAlgorithmException

Constructor that creates a helper that uses the provided algorithm.

Parameters:

algorithm - the algorithm this helper will use

Throws:

NoSuchAlgorithmException - thrown if the algorithm is not supported

Method Detail

digest

public byte[] digest(SecretKey key,
                     byte[] data)
              throws InvalidKeyException

Creates the message digest using the helpers algorithm for the given data using the given key.

Parameters:

key - the key to generate the digest with

data - the data to generate the digest with

Returns:

the message digest using the helpers algorithm for the given data using the given key

Throws:

InvalidKeyException - thrown is the key is not the correct format

generateKey

public SecretKey generateKey(byte[] encodedKey)

This generates a SecretKey from the given key bytes using the helpers MacAlgorithm.

Parameters:

encodedKey - the HMAC key encoded bytes

Returns:

the SecretKey with the encoded bytes and algorithm

generateKey

public SecretKey generateKey()
                      throws NoSuchAlgorithmException

This generates a new SecretKey using the helpers MacAlgorithm.

Returns:

a new SecretKey with the helpers algorithm

Throws:

NoSuchAlgorithmException - thrown if the helpers algorithm is not supported

verify

public boolean verify(SecretKey key,
                      byte[] data,
                      byte[] digest)
               throws InvalidKeyException

This will check to see if the passed in digest matches the digest created from the passed in key and data. NOTE: this will create the digest using the digest(SecretKey, byte[]) method. That method will use the MacAlgorithm defined for this helper.

Parameters:

key - the key used to create the digest

data - the data use to create teh digest

digest - the digest to verify

Returns:

true if the digest created from the key and data match the passed in digest value

Throws:

InvalidKeyException - thrown is the key is not the correct format