info.pppc.base.plugin.security.dh

Class AbstractExchange

java.lang.Object

info.pppc.base.plugin.security.dh.AbstractExchange

Direct Known Subclasses:

DHExchange, ECDHExchange

public abstract class AbstractExchange
extends java.lang.Object

The abstract class for all types of DH key-exchanges. A DH key-exchange creates a shared secret between two parties. Both parties need to first call the create method, then to send the created integer to the corresponding communication partner. After receiving this message, they call the get secret method and obtain a shared secret (a SHA256 hash) that can be directly used for key creation.

Author:

Wolfgang Apolinarski

Field Summary

Fields

Modifier and Type	Field and Description
static short	PERFORM_ECDH The identifier that is used to signal that normal ECDH should be performed.
static short	PERFORM_FAST_ECDH The identifier that is used to signal that fast ECDH should be performed, this is ignored in the j2se version.
static short	PERFORM_NORMAL_DH The identifier that is used to signal that normal DH should be performed.

Constructor Summary

Constructors

Constructor and Description
AbstractExchange()

Method Summary

Methods

Modifier and Type	Method and Description
static AbstractExchange	createInstance() Backup instance creation.
static AbstractExchange	createInstance(short exchangeSemanticType) Creates a new instance of the DH-Key-Exchange either using the fast ECDH (only with SECP160R1), ECDH or the normal DH.
abstract byte[]	createLocalSecret() Creates the the BigInteger of this communication end-point.
abstract byte[]	getSharedSecret(byte[] integer) Creates the shared secret out of the public BigInteger from the communication partner.
static java.lang.Class<? extends AbstractExchange>	registerInstance(short semantic, java.lang.Class<? extends AbstractExchange> exchangeClass) Registers a particular exchange class for handling the exchange of a certain type.

Methods inherited from class java.lang.Object

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

Field Detail

PERFORM_NORMAL_DH

public static final short PERFORM_NORMAL_DH

The identifier that is used to signal that normal DH should be performed.

See Also:

Constant Field Values

PERFORM_ECDH

public static final short PERFORM_ECDH

The identifier that is used to signal that normal ECDH should be performed.

See Also:

Constant Field Values

PERFORM_FAST_ECDH

public static final short PERFORM_FAST_ECDH

The identifier that is used to signal that fast ECDH should be performed, this is ignored in the j2se version.

See Also:

Constant Field Values

Constructor Detail

AbstractExchange

public AbstractExchange()

Method Detail

createLocalSecret

public abstract byte[] createLocalSecret()
                                  throws java.io.IOException

Creates the the BigInteger of this communication end-point. This integer should be transferred to the communication partner.

Returns:

A BigInteger (g^a). This message can be read by anybody without revealing the shared secret.

Throws:

java.io.IOException

getSharedSecret

public abstract byte[] getSharedSecret(byte[] integer)
                                throws java.io.IOException

Creates the shared secret out of the public BigInteger from the communication partner. The returned bytes can directly be transformed into a shared secret key.

Parameters:

integer - The BigInteger that was obtained from the communication partner, i.e. the partners public key

Returns:

32 bytes that can directly be used to create a shared symmetric key.

Throws:

java.io.IOException

registerInstance

public static java.lang.Class<? extends AbstractExchange> registerInstance(short semantic,
                                                           java.lang.Class<? extends AbstractExchange> exchangeClass)

Registers a particular exchange class for handling the exchange of a certain type.

Parameters:

semantic -

exchangeClass -

Returns:

createInstance

public static AbstractExchange createInstance()

Backup instance creation. Please implement a identical static method, if you override this class.

Returns:

A DHExchange object.

createInstance

public static AbstractExchange createInstance(short exchangeSemanticType)

Creates a new instance of the DH-Key-Exchange either using the fast ECDH (only with SECP160R1), ECDH or the normal DH.

Parameters:

exchangeSemanticType - A constant that shows which type of DH should be used, e.g. ExchangeSemantic#PERFORM_NORMAL_DH

Returns:

An instance of the DH-Key-Exchange that fits the given certificate

See Also:

ExchangeSemantic