iaik.security.dh
Class ESDHPublicKey

java.lang.Object
  |
  +--iaik.x509.PublicKeyInfo
        |
        +--iaik.security.dh.ESDHPublicKey

All Implemented Interfaces:

ASN1Type, Cloneable, DHKey, DHPublicKey, Key, PublicKey, Serializable

public class ESDHPublicKey

extends PublicKeyInfo

implements DHPublicKey, Serializable

This class implements an Ephemeral Static Diffie Hellman public key.

This class extends iaik.x509.PublicKeyInfo for supporting ESDH public keys to be used within X.509 certificates . An ESDH Hellman public key maybe generated using a proper key pair generator, e.g.:

 KeyPairGnerator esdh_key_gen = KeyPairGenerator.getInstance("ESDH");
 esdh_key_gen.initialize(1024);
 KeyPair esdh_key_pair = esdh_key_gen.generateKeyPair();
 ESDHPublicKey dh_priv_key = (ESDHPublicKey)esdh_key_pair.getPublic();
 

Version:

File Revision 17

See Also:

KeyPairGenerator, KeyPair, KeyAgreement, ESDHPublicKeySpec, ESDHPrivateKey, ESDHKeyPairGenerator, ESDHKeyFactory, ESDHParameters, ESDHParameterGenerator, ESDHKeyAgreement, PublicKeyInfo, Serialized Form

Fields inherited from class iaik.x509.PublicKeyInfo

public_key_algorithm

Fields inherited from interface java.security.PublicKey

serialVersionUID

Constructor Summary

ESDHPublicKey(ASN1Object obj)
Creates a new ESDHPublicKey from the given ASN.1 object.

ESDHPublicKey(BigInteger y, ESDHParameterSpec parameters)
Creates a new ESDHPublicKey from public key value and ESDH parameter specification

ESDHPublicKey(byte[] pk)
Creates a new ESDHPublicKey from the given DER encoded byte array.

ESDHPublicKey(ESDHPublicKeySpec keySpec)
Creates a new ESDHPublicKey from the given ESDHPublicKeySpec representing the ESDH public key value y, and the values p, g, q, j (if available) and seed and pgenCounter (if available).

ESDHPublicKey(InputStream is)
Creates a new ESDHPublicKey from an InputStream.

Method Summary

protected void	decode(byte[] publicKey) Decodes an ESDHPublicKey, encoded in DER format.
protected byte[]	encode() Returns this ESDH public key as DER encoded ASN.1 object.
String	getAlgorithm() Returns the name of the appertaining algorithm.
byte[]	getFingerprint() Returns the fingerprint of this ESDH public key.
DHParameterSpec	getParams() Returns the key parameters.
BigInteger	getY() Returns the public value y as BigInteger.
int	hashCode() Returns a hash code for this object.
String	toString() Returns a string that represents the contents of this public key.
static void	validatePublicKey(ESDHPublicKey esdhPublicKey) Validates an ESDH public key.

Methods inherited from class iaik.x509.PublicKeyInfo

clone, createPublicKeyInfo, decode, equals, getEncoded, getFormat, getPublicKey, getPublicKey, toASN1Object, writeTo

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.security.Key

getEncoded, getFormat

Constructor Detail

ESDHPublicKey

public ESDHPublicKey(BigInteger y,
                     ESDHParameterSpec parameters)

Creates a new ESDHPublicKey from public key value and ESDH parameter specification

Parameters:

y - the BigInteger value representing the ESDH public key value y

parameters - the ESDH parameters p (prime modulus), g (base generator), prime factor q, the subgroup factor j (if available) and the seed seed and pgenCounter pgenCounter (if available) as ESDHParameterSpec

ESDHPublicKey

public ESDHPublicKey(ESDHPublicKeySpec keySpec)

Creates a new ESDHPublicKey from the given ESDHPublicKeySpec representing the ESDH public key value y, and the values p, g, q, j (if available) and seed and pgenCounter (if available).

Parameters:

keySpec - the ESDHPublicKeySpec representing the public key value y, the prime modulus p, the base generator g, the subgroup factor j (if available) and the seed seed and pgenCounter pgenCounter (if available)

ESDHPublicKey

public ESDHPublicKey(byte[] pk)
              throws InvalidKeyException

Creates a new ESDHPublicKey from the given DER encoded byte array.

This constructor may be used for parsing an already exisiting ESDH public key, wrapped into a X.509 PublicKeyInfo that is supplied as DER encoded byte array.

Parameters:

the - byte array holding the DER encoded public key info

Throws:

InvalidKeyException - if something is wrong with the key encoding

ESDHPublicKey

public ESDHPublicKey(ASN1Object obj)
              throws InvalidKeyException

Creates a new ESDHPublicKey from the given ASN.1 object. The supplied ASN1Object represents a X.509 PublicKeyInfo holding the ESDH public key.

Parameters:

obj - the public key ASN.1 data structure

Throws:

InvalidKeyException - if something is wrong with the key encoding

ESDHPublicKey

public ESDHPublicKey(InputStream is)
              throws IOException,
                     InvalidKeyException

Creates a new ESDHPublicKey from an InputStream.

This constructor may be used for parsing an already exisiting ESDH public key, wrapped into a X.509 PublicKeyInfo that is supplied as DER encoded byte array.

Parameters:

is - the input stream with the data to be read to initialize the public key

Throws:

IOException - if an I/O error occurs

InvalidKeyException - if something is wrong with the key encoding

Method Detail

validatePublicKey

public static void validatePublicKey(ESDHPublicKey esdhPublicKey)
                              throws InvalidKeyException

Validates an ESDH public key. Note that this procedure may be subject to pending patents (see RFC 2631). For that reason and for performance reasons public keys are not validated automatically. An application itself may decide to do so.

Parameters:

esdhPublicKey - the public key to be validated

Throws:

InvalidKeyException - if validation fails

decode

protected void decode(byte[] publicKey)
               throws InvalidKeyException

Decodes an ESDHPublicKey, encoded in DER format.

From the given DER encoded byte array an ASN.1 object is created and parsed for the public key value y and the ESDH parameters prime p and base g, prime factor q, the subgroup factor j (if available) and the seed seed and pgenCounter pgenCounter (if available).

This method is protected and typically will not be used by an application. Rather it is used by the parent X.509 PublicKeyInfo class for decoding the inherent ESDH public key.

Overrides:

decode in class PublicKeyInfo

Parameters:

publicKey - the public key as DER encoded ASN.1 object

Throws:

InvalidKeyException - if the given key is not a ESDH public key

encode

protected byte[] encode()

Returns this ESDH public key as DER encoded ASN.1 object.

This method is protected and typically will not be used by an application. Rather it is used by the parent X.509 PublicKeyInfo class for encoding the inherent ESDH public key.

Overrides:

encode in class PublicKeyInfo

Returns:

a byte array holding the ESDH public key as a DER encoded ASN.1 data structure

getAlgorithm

public String getAlgorithm()

Returns the name of the appertaining algorithm.

Specified by:

getAlgorithm in interface Key

Overrides:

getAlgorithm in class PublicKeyInfo

Returns:

the string "ESDH"

getY

public BigInteger getY()

Returns the public value y as BigInteger.

Specified by:

getY in interface DHPublicKey

Returns:

the public value y as BigInteger

getParams

public DHParameterSpec getParams()

Returns the key parameters.

Specified by:

getParams in interface DHKey

Returns:

the key parameters as ESDHParameterSpec

getFingerprint

public byte[] getFingerprint()

Returns the fingerprint of this ESDH public key. This is a MD5 hash of the DER encoded SubjectPublicKey.

Overrides:

getFingerprint in class PublicKeyInfo

Returns:

the fingerprint of this ESDH public key

hashCode

public int hashCode()

Returns a hash code for this object.

Overrides:

hashCode in class PublicKeyInfo

Returns:

the hash code

toString

public String toString()

Returns a string that represents the contents of this public key.

Overrides:

toString in class PublicKeyInfo

Returns:

the string representation