iaik.security.ecc.ecdh
Class ECDH

java.lang.Object
  javax.crypto.KeyAgreementSpi
      iaik.security.ecc.ecdh.ECDH

Direct Known Subclasses:

ECDHwithCofactor

public class ECDH

extends javax.crypto.KeyAgreementSpi

DLSVDP-DH is Discrete Logarithm Secret Value Derivation Primitive, Diffie-Hellman version, compliant with IEEE 1363 and DLSVDP-DHC is Discrete Logarithm Secret Value Derivation Primitive, Diffie-Hellman version with cofactor multiplication.

This implementation doesn't perform a parameter check. Both, the private and the public key have to use the same parameter set.

Field Summary

protected ECDSAParams	parameter_ The used parameter set.
protected ECDSAPrivateKey	privateKey_ The private key for this key agreement.
protected byte[]	secret_ The generated shared secret.
protected boolean	withCoFactor_ if true the algorithm uses cofactor multiplication.

Constructor Summary

	ECDH() Constructor used by provider.
protected	ECDH(boolean withCoFactorMultiplication) Creates a new ECDH instance.

Method Summary

protected java.security.Key	engineDoPhase(java.security.Key publicKey, boolean lastPhase) Performs the shared secret calculation, which is the x coordinate of the point p = puplicKey * privateKey (*cofactor).
protected byte[]	engineGenerateSecret() The result of this key agreement scheme, which is the x coordinate of the new ec point.
protected int	engineGenerateSecret(byte[] sharedSecret, int offset) After the last phase, this method copies the result in the provided buffer.
protected javax.crypto.SecretKey	engineGenerateSecret(java.lang.String algorithm) Describe engineGenerateSecret method here.
protected void	engineInit(java.security.Key privateKey, java.security.spec.AlgorithmParameterSpec param, java.security.SecureRandom random) Initializes this key agreement with a private key and an parameter set.
protected void	engineInit(java.security.Key privateKey, java.security.SecureRandom secureRandom) Initializes this with a given private key.
protected boolean	equalParameters(ECDSAParams p1, ECDSAParams p2) Compares 2 domain parameter sets.

Methods inherited from class java.lang.Object

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

Field Detail

parameter_

protected ECDSAParams parameter_

The used parameter set.

privateKey_

protected ECDSAPrivateKey privateKey_

The private key for this key agreement.

secret_

protected byte[] secret_

The generated shared secret.

withCoFactor_

protected boolean withCoFactor_

if true the algorithm uses cofactor multiplication.

Constructor Detail

ECDH

public ECDH()

Constructor used by provider. It simply calls this(flase). Don't try to get an instance of this class but use the provider.

ECDH

protected ECDH(boolean withCoFactorMultiplication)

Creates a new ECDH instance. Don't try to get an instance of this class but use the provider.

Parameters:

withCoFactorMultiplication - a boolean value, if true cofactor multiplication is used.

Method Detail

engineDoPhase

protected java.security.Key engineDoPhase(java.security.Key publicKey,
                                          boolean lastPhase)
                                   throws java.lang.IllegalStateException,
                                          java.security.InvalidKeyException

Performs the shared secret calculation, which is the x coordinate of the point p = puplicKey * privateKey (*cofactor).

Parameters:

publicKey - a Key value which is the peers public key and MUST use the same domain parameter as the used private key.

lastPhase - a boolean value indicates if this is the last phase in this scheme.

Returns:

a Key value, which is null if the lastPhase parameter is true.

Throws:

java.lang.IllegalStateException - if an error occurs

java.security.InvalidKeyException - if an error occurs

engineGenerateSecret

protected byte[] engineGenerateSecret()
                               throws java.lang.IllegalStateException

The result of this key agreement scheme, which is the x coordinate of the new ec point.

Returns:

a byte[] value which is the result of this key agreement.

Throws:

java.lang.IllegalStateException - never occurs.

engineGenerateSecret

protected int engineGenerateSecret(byte[] sharedSecret,
                                   int offset)
                            throws javax.crypto.ShortBufferException,
                                   java.lang.IllegalStateException

After the last phase, this method copies the result in the provided buffer.

Parameters:

sharedSecret - a byte[] value to hold the secret

offset - an int value specifies the buffer offset

Returns:

an int value, which is the length of the secret

Throws:

javax.crypto.ShortBufferException - if the provided buffer is too small

java.lang.IllegalStateException - never thrown.

engineGenerateSecret

protected javax.crypto.SecretKey engineGenerateSecret(java.lang.String algorithm)
                                               throws java.security.InvalidKeyException,
                                                      java.security.NoSuchAlgorithmException,
                                                      java.lang.IllegalStateException

Describe engineGenerateSecret method here.

Parameters:

algorithm - a String value value describing the secret key algorithm.

Returns:

a SecretKey value of the specified type.

Throws:

java.security.InvalidKeyException - if an error occurs

java.security.NoSuchAlgorithmException - if an error occurs

java.lang.IllegalStateException - if an error occurs

engineInit

protected void engineInit(java.security.Key privateKey,
                          java.security.spec.AlgorithmParameterSpec param,
                          java.security.SecureRandom random)
                   throws java.security.InvalidAlgorithmParameterException,
                          java.security.InvalidKeyException

Initializes this key agreement with a private key and an parameter set. ATTENTION the private key must be intended for this parameter set. This property will not be checked.

Throws:

java.security.InvalidAlgorithmParameterException

java.security.InvalidKeyException

engineInit

protected void engineInit(java.security.Key privateKey,
                          java.security.SecureRandom secureRandom)
                   throws java.security.InvalidKeyException

Initializes this with a given private key. The secure random parameter is ignored.

Parameters:

privateKey - a Key value, which must be a private ec key

secureRandom - a SecureRandom value

Throws:

java.security.InvalidKeyException - if the provided key is invalid.

equalParameters

protected boolean equalParameters(ECDSAParams p1,
                                  ECDSAParams p2)

Compares 2 domain parameter sets. The base points and the orders must be equal. If a cofactor is defined in both sets it must be equal as well.

Parameters:

p1 - parameters to be compared

p2 - parameters to be compared

Returns:

a boolean value if the parameters are equal.