gnu.crypto.mac.IMac Maven / Gradle / Ivy
package gnu.crypto.mac;
// ----------------------------------------------------------------------------
// $Id: IMac.java,v 1.2 2002/11/07 17:17:45 raif Exp $
//
// Copyright (C) 2001, 2002, Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU Crypto is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING. If not, write to the
//
// Free Software Foundation Inc.,
// 59 Temple Place - Suite 330,
// Boston, MA 02111-1307
// USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module. An independent module is a module which is
// not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so. If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------
import java.util.Map;
import java.security.InvalidKeyException;
/**
* The basic visible methods of any MAC (Message Authentication Code)
* 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, MACs are used between two parties, that share a common
* secret key, in order to validate information transmitted between them.
*
* When a MAC algorithm is based on a cryptographic hash function, it
* is then called to a HMAC (Hashed Message Authentication Code) --see
* RFC-2104.
*
* Another type of MAC algorithms exist: UMAC or Universal Message
* Authentication Code, described in
*
* draft-krovetz-umac-01.txt.
*
* With UMACs, the sender and receiver share a common secret key (the
* MAC key) which determines:
*
*
* - The key for a universal hash function. This hash function is
* non-cryptographic, in the sense that it does not need to have any
* cryptographic hardness property. Rather, it needs to satisfy some
* combinatorial property, which can be proven to hold without relying on
* unproven hardness assumptions.
*
* - The key for a pseudorandom function. This is where one needs a
* cryptographic hardness assumption. The pseudorandom function may be
* obtained from a block cipher or a cryptographic hash function.
*
*
*
* References:
*
*
* - RFC 2104HMAC:
* Keyed-Hashing for Message Authentication.
* H. Krawczyk, M. Bellare, and R. Canetti.
*
* -
* UMAC: Message Authentication Code using Universal Hashing.
* T. Krovetz, J. Black, S. Halevi, A. Hevia, H. Krawczyk, and P. Rogaway.
*
*
* @version $Revision: 1.2 $
*/
public interface IMac extends Cloneable {
// Constants
// -------------------------------------------------------------------------
/**
* Property name of the user-supplied key material. The value associated to
* this property name is taken to be a byte array.
*/
String MAC_KEY_MATERIAL = "gnu.crypto.mac.key.material";
/**
* Property name of the desired truncated output size in bytes. The value
* associated to this property name is taken to be an integer. If no value
* is specified in the attributes map at initialisation time, then all bytes
* of the underlying hash algorithm's output are emitted.
*
* This implementation, follows the recommendation of the RFC 2104
* authors; specifically:
*
*
* We recommend that the output length t be not less than half the
* length of the hash output (to match the birthday attack bound)
* and not less than 80 bits (a suitable lower bound on the number
* of bits that need to be predicted by an attacker).
*
*/
String TRUNCATED_SIZE = "gnu.crypto.mac.truncated.size";
// Methods
// -------------------------------------------------------------------------
/**
* Returns the canonical name of this algorithm.
*
* @return the canonical name of this algorithm.
*/
String name();
/**
* Returns the output length in bytes of this MAC algorithm.
*
* @return the output length in bytes of this MAC algorithm.
*/
int macSize();
/**
* Initialises the algorithm with designated attributes. Permissible names
* and values are described in the class documentation above.
*
* @param attributes a set of name-value pairs that describe the desired
* future instance behaviour.
* @exception InvalidKeyException if the key data is invalid.
* @exception IllegalStateException if the instance is already initialised.
* @see #MAC_KEY_MATERIAL
*/
void init(Map attributes)
throws InvalidKeyException, IllegalStateException;
/**
* Continues a MAC operation using the input byte.
*
* @param b the input byte to digest.
*/
void update(byte b);
/**
* Continues a MAC operation, by filling the buffer, processing
* data in the algorithm's MAC_SIZE-bit block(s), updating the context and
* count, and buffering the remaining bytes in buffer for the next
* operation.
*
* @param in the input block.
* @param offset start of meaningful bytes in input block.
* @param length number of bytes, in input block, to consider.
*/
void update(byte[] in, int offset, int length);
/**
* Completes the MAC by performing final operations such as
* padding and resetting the instance.
*
* @return the array of bytes representing the MAC value.
*/
byte[] digest();
/**
* Resets the algorithm instance for re-initialisation and use with other
* characteristics. This method always succeeds.
*/
void reset();
/**
* A basic test. Ensures that the MAC of a pre-determined message is equal
* to a known pre-computed value.
*
* @return true if the implementation passes a basic self-test.
* Returns false otherwise.
*/
boolean selfTest();
/**
* Returns a clone copy of this instance.
*
* @return a clone copy of this instance.
*/
Object clone();
}