com.ibm.crypto.provider
Class HmacSHA256

java.lang.Object
  extended by javax.crypto.MacSpi
      extended by com.ibm.crypto.provider.HmacSHA256
All Implemented Interfaces:
Cloneable

public final class HmacSHA256
extends MacSpi
implements Cloneable

This is an implementation of the HMAC-SHA256 algorithm.


Constructor Summary
HmacSHA256()
          Standard constructor, creates a new HmacSHA256 instance.
 
Method Summary
 Object clone()
          Returns a clone if the implementation is cloneable.
protected  byte[] engineDoFinal()
          Completes the HMAC computation and resets the HMAC for further use, maintaining the secret key that the HMAC was initialized with.
protected  int engineGetMacLength()
          Returns the length of the HMAC in bytes.
protected  void engineInit(Key key, AlgorithmParameterSpec params)
          Initializes the HMAC with the given secret key and algorithm parameters.
protected  void engineReset()
          Resets the HMAC for further use, maintaining the secret key that the HMAC was initialized with.
protected  void engineUpdate(byte input)
          Processes the given byte.
protected  void engineUpdate(byte[] input, int offset, int len)
          Processes the first len bytes in input, starting at offset.
 
Methods inherited from class javax.crypto.MacSpi
engineUpdate
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

HmacSHA256

public HmacSHA256()
           throws NoSuchAlgorithmException
Standard constructor, creates a new HmacSHA256 instance. Verify the JCE framework in the constructor.

Throws:
SecurityException - if fails to verify the JCE framework.
NoSuchAlgorithmException
Method Detail

engineGetMacLength

protected int engineGetMacLength()
Returns the length of the HMAC in bytes.

Specified by:
engineGetMacLength in class MacSpi
Returns:
the HMAC length in bytes.

engineInit

protected void engineInit(Key key,
                          AlgorithmParameterSpec params)
                   throws InvalidKeyException,
                          InvalidAlgorithmParameterException
Initializes the HMAC with the given secret key and algorithm parameters.

Specified by:
engineInit in class MacSpi
Parameters:
key - the secret key.
params - 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.

engineUpdate

protected void engineUpdate(byte input)
Processes the given byte.

Specified by:
engineUpdate in class MacSpi
Parameters:
input - the input byte to be processed.

engineUpdate

protected void engineUpdate(byte[] input,
                            int offset,
                            int len)
Processes the first len bytes in input, starting at offset.

Specified by:
engineUpdate in class MacSpi
Parameters:
input - the input buffer.
offset - the offset in input where the input starts.
len - the number of bytes to process.

engineDoFinal

protected byte[] engineDoFinal()
Completes the HMAC computation and resets the HMAC for further use, maintaining the secret key that the HMAC was initialized with.

Specified by:
engineDoFinal in class MacSpi
Returns:
the HMAC result.

engineReset

protected void engineReset()
Resets the HMAC for further use, maintaining the secret key that the HMAC was initialized with.

Specified by:
engineReset in class MacSpi

clone

public Object clone()
Description copied from class: MacSpi
Returns a clone if the implementation is cloneable.

Overrides:
clone in class MacSpi
Returns:
a clone if the implementation is cloneable.