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oracle.security.crypto.core
Class DiffieHellman

java.lang.Object
oracle.security.crypto.core.DiffieHellman

public final class DiffieHellman

extends java.lang.Object

Implementation of the Diffie-Hellman public key agreement algorithm, as defined in PKCS#3.

Once a DiffieHellman object has been instantiated, use the myValue() method to obtain the value to send to the peer (g^x). The method getKey(java.math.BigInteger) is used to compute the shared Diffie-Hellman key value.

Constructor Summary

DiffieHellman()
Creates a new, uninitialized DiffieHellman instance.

DiffieHellman(java.math.BigInteger p, java.math.BigInteger g, RandomBitsSource rbs)
Constructs a DiffieHellman object with the specified values for the prime (p) and generator (g), and creates a random value for x.

DiffieHellman(RandomBitsSource rbs, int len)
Constructs a DiffieHellman object, creating a random prime (p) of the given bit length, and a random value x; the generator (g) is set to 4.

Method Summary

void	erase() Erases the values for this key agreement.
void	finalize() Finalizes this instance by erasing all sensitive data.
protected void	generatePandG(RandomBitsSource rbs, int len) Generates a random prime (p) of the given bit length for this DiffieHellman and sets the generator (g) to 4.
protected void	generateValues(RandomBitsSource rbs) Generates a large random integer (x) for this DiffieHellman, and uses its prime (p) and generator (g) to compute the value g^x.
java.math.BigInteger	getGen() Returns the generator (g).
static DiffieHellman	getInstance() Returns an uninitialized DiffieHellman instance.
static DiffieHellman	getInstance(java.math.BigInteger p, java.math.BigInteger g, RandomBitsSource rbs) Returns an initialized DiffieHellman instance.
static DiffieHellman	getInstance(RandomBitsSource rbs, int len) Returns an initialized DiffieHellman instance.
java.math.BigInteger	getKey(java.math.BigInteger gy) Computes the shared DH key value g^(xy).
java.math.BigInteger	getPrime() Returns the prime (p).
void	initialize(java.math.BigInteger p, java.math.BigInteger g, RandomBitsSource rbs) Sets the prime (p) and generator (g) for this DiffieHellman, and invokes generateValues(oracle.security.crypto.core.RandomBitsSource).
void	initialize(RandomBitsSource rbs, int len) Generates the prime (p), generator (g) and values (x and g^x) by invoking generatePandG(oracle.security.crypto.core.RandomBitsSource, int) and generateValues(oracle.security.crypto.core.RandomBitsSource).
java.math.BigInteger	myValue() Returns the generated value g^x.
java.lang.String	toString() Returns a string representation of this object.

Methods inherited from class java.lang.Object

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

Constructor Detail

DiffieHellman

public DiffieHellman()

Creates a new, uninitialized DiffieHellman instance.

DiffieHellman

public DiffieHellman(RandomBitsSource rbs,
                     int len)
              throws java.lang.IllegalArgumentException

Constructs a DiffieHellman object, creating a random prime (p) of the given bit length, and a random value x; the generator (g) is set to 4.

Throws:

java.lang.IllegalArgumentException

DiffieHellman

public DiffieHellman(java.math.BigInteger p,
                     java.math.BigInteger g,
                     RandomBitsSource rbs)

Constructs a DiffieHellman object with the specified values for the prime (p) and generator (g), and creates a random value for x.

Method Detail

getInstance

public static DiffieHellman getInstance()
                                 throws AlgorithmIdentifierException

Returns an uninitialized DiffieHellman instance.

Throws:

AlgorithmIdentifierException

getInstance

public static DiffieHellman getInstance(RandomBitsSource rbs,
                                        int len)
                                 throws java.lang.IllegalArgumentException,
                                        AlgorithmIdentifierException

Returns an initialized DiffieHellman instance.

Parameters:

rbs - The RandomBitsSource to use in this DiffieHellman object.

len - The bit length of the prime.

Throws:

java.lang.IllegalArgumentException

AlgorithmIdentifierException

getInstance

public static DiffieHellman getInstance(java.math.BigInteger p,
                                        java.math.BigInteger g,
                                        RandomBitsSource rbs)
                                 throws AlgorithmIdentifierException

Returns an initialized DiffieHellman instance.

Parameters:

p - The BigInteger prime p.

g - The BigInteger generator g.

rbs - The RandomBitsSource to use in this DiffieHellman object.

Throws:

AlgorithmIdentifierException

initialize

public void initialize(RandomBitsSource rbs,
                       int len)

Generates the prime (p), generator (g) and values (x and g^x) by invoking generatePandG(oracle.security.crypto.core.RandomBitsSource, int) and generateValues(oracle.security.crypto.core.RandomBitsSource).

initialize

public void initialize(java.math.BigInteger p,
                       java.math.BigInteger g,
                       RandomBitsSource rbs)

Sets the prime (p) and generator (g) for this DiffieHellman, and invokes generateValues(oracle.security.crypto.core.RandomBitsSource).

generatePandG

protected void generatePandG(RandomBitsSource rbs,
                             int len)

Generates a random prime (p) of the given bit length for this DiffieHellman and sets the generator (g) to 4.

generateValues

protected void generateValues(RandomBitsSource rbs)

Generates a large random integer (x) for this DiffieHellman, and uses its prime (p) and generator (g) to compute the value g^x.

getPrime

public java.math.BigInteger getPrime()

Returns the prime (p).

getGen

public java.math.BigInteger getGen()

Returns the generator (g).

myValue

public java.math.BigInteger myValue()

Returns the generated value g^x.

getKey

public java.math.BigInteger getKey(java.math.BigInteger gy)

Computes the shared DH key value g^(xy).

Parameters:

gy - The generated value received from the peer.

toString

public java.lang.String toString()

Returns a string representation of this object.

Overrides:

toString in class java.lang.Object

erase

public void erase()

Erases the values for this key agreement.

finalize

public void finalize()

Finalizes this instance by erasing all sensitive data.

Overrides:

finalize in class java.lang.Object

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