iaik.security.mac
Class HMacSha

java.lang.Object
  |
  +--javax.crypto.MacSpi
        |
        +--iaik.security.mac.HMac
              |
              +--iaik.security.mac.HMacSha

public class HMacSha

extends HMac

This class implements the HMAC(Keyed-Hashing for Message Authentication) algorithm as defined in RFC 2104 with Secure Hash Algorithm as message digest algorithm.

This class only instantiates the super HMac class and specifies SHA as hash algorithm to be used.

An application wishing to perform a MAC computation, at first has to create a MAC object by instantiating the MAC class through a proper getInstance factory method thereby specifying the MAC algorithm to be used. Calculating a HMAC based on the Sha hash algorithm, may be initiated as follows:

 MAC sha_HMAC = MAC.getInstance("HMAC/SHA");
 

After properly initializing the MAC object with one entity´s secret key, the data to be processed is applied by one (or more) calls to the update methods. The MAC computation is concluded by using doFinal. If the data can be processed without calling any update method, doFinal can be called immediately after initializing the MAC object:

 sha_HMAC.init(secret_key);
 byte[] mac_data = sha_HMAC.doFinal(data);
 

After the MAC finally has been calculated, the MAC object automatically is reset for being able to be used for further MAC computations, either by using the same secret key again, or using a new key by properly re-initializing this MAC object.

Version:

File Revision 13

See Also:

HMac, HMacMd5, SHA

Constructor Summary

HMacSha()
Default constructor.

Methods inherited from class iaik.security.mac.HMac

engineDoFinal, engineGetMacLength, engineInit, engineReset, engineUpdate, engineUpdate

Methods inherited from class javax.crypto.MacSpi

clone

Methods inherited from class java.lang.Object

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

Constructor Detail

HMacSha

public HMacSha()
        throws NoSuchAlgorithmException

Default constructor. This constructor only calls the constructor of super HMac class thereby specifying SHA as hash function to be used.

Throws:

NoSuchAlgorithmException - if there is no implementation for SHA