iaik.security.elgamal

Class ElGamalPublicKey

java.lang.Object

iaik.x509.PublicKeyInfo

iaik.security.elgamal.ElGamalPublicKey

All Implemented Interfaces:

ASN1Type, java.io.Serializable, java.lang.Cloneable, java.security.Key, java.security.PublicKey

public class ElGamalPublicKey
extends PublicKeyInfo

This class implements a ElGamal public key and supports ASN.1 encoding.

See Also:

Serialized Form

Field Summary

Fields inherited from class iaik.x509.PublicKeyInfo

public_key_algorithm

Constructor Summary

Constructors

Constructor and Description
ElGamalPublicKey(ASN1Object obj) Creates a new ElGamalPublicKey from the given ASN.1 object.
ElGamalPublicKey(java.math.BigInteger y, ElGamalParameterSpec parameters) Creates a new ElGamalPublicKey from public key value and ElGamal parameter specification
ElGamalPublicKey(byte[] pk) Creates a new ElGamalPublicKey from the given DER encoded byte array.
ElGamalPublicKey(ElGamalPublicKeySpec keySpec) Creates a new ElGamalPublicKey from the given ElGamalPublicKeySpec representing the ElGamal public key value y, and the public values p, g and l.
ElGamalPublicKey(java.io.InputStream is) Creates a new ElGamalPublicKey from an InputStream.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	decode(byte[] publicKey) Decodes a ElGamalPublicKey, encoded in DER format.
byte[]	encode() Returns the raw ElGamal public key (not wrapped in a X.509 PublicKeyInfo) as DER encoded ASN.1 object.
java.lang.String	getAlgorithm() Returns the name of the appertaining algorithm.
byte[]	getFingerprint() Returns the fingerprint of this ElGamal public key.
ElGamalParameterSpec	getParams() Returns the key parameters.
java.math.BigInteger	getY() Returns the public value y as BigInteger.
int	hashCode() Returns a hash code for this object.
java.lang.String	toString() Returns a string that represents the contents of this public key.

Methods inherited from class iaik.x509.PublicKeyInfo

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

Methods inherited from class java.lang.Object

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

Constructor Detail

ElGamalPublicKey

public ElGamalPublicKey(java.math.BigInteger y,
                ElGamalParameterSpec parameters)

Creates a new ElGamalPublicKey from public key value and ElGamal parameter specification

Parameters:

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

parameters - the ElGamal parameters p (prime modulus), g (base generator) and l (length of the private value x) as ElGamalParameterSpec

ElGamalPublicKey

public ElGamalPublicKey(ElGamalPublicKeySpec keySpec)

Creates a new ElGamalPublicKey from the given ElGamalPublicKeySpec representing the ElGamal public key value y, and the public values p, g and l.

Parameters:

keySpec - the ElGamalPublicKeySpec representing the public key value y, the prime modulus p, the base generator g, and the length l of the private value

ElGamalPublicKey

public ElGamalPublicKey(byte[] pk)
                 throws java.security.InvalidKeyException

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

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

Parameters:

pk - the byte array holding the DER encoded public key info

Throws:

java.security.InvalidKeyException - if something is wrong with the key encoding

ElGamalPublicKey

public ElGamalPublicKey(ASN1Object obj)
                 throws java.security.InvalidKeyException

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

Parameters:

obj - the public key ASN.1 data structure

Throws:

java.security.InvalidKeyException - if something is wrong with the key encoding

ElGamalPublicKey

public ElGamalPublicKey(java.io.InputStream is)
                 throws java.io.IOException,
                        java.security.InvalidKeyException

Creates a new ElGamalPublicKey from an InputStream.

This constructor may be used for parsing an already existing ElGamal 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:

java.io.IOException - if an I/O error occurs

java.security.InvalidKeyException - if something is wrong with the key encoding

Method Detail

decode

protected void decode(byte[] publicKey)
               throws java.security.InvalidKeyException

Decodes a ElGamalPublicKey, 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 ElGamal parameters prime p and base g, and - if included - the length l of the private value x.

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 ElGamal public key.

Specified by:

decode in class PublicKeyInfo

Parameters:

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

Throws:

java.security.InvalidKeyException - if the given key is not a ElGamal public key

encode

public byte[] encode()

Returns the raw ElGamal public key (not wrapped in a X.509 PublicKeyInfo) as DER encoded ASN.1 object.

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

Specified by:

encode in class PublicKeyInfo

Returns:

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

getAlgorithm

public java.lang.String getAlgorithm()

Returns the name of the appertaining algorithm.

Specified by:

getAlgorithm in interface java.security.Key

Specified by:

getAlgorithm in class PublicKeyInfo

Returns:

the string "ElGamal"

getY

public java.math.BigInteger getY()

Returns the public value y as BigInteger.

Returns:

the public value y as BigInteger

getParams

public ElGamalParameterSpec getParams()

Returns the key parameters.

Returns:

the key parameters as ElGamalParameterSpec

getFingerprint

public byte[] getFingerprint()

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

Overrides:

getFingerprint in class PublicKeyInfo

Returns:

the fingerprint of this ElGamal public key

hashCode

public int hashCode()

Returns a hash code for this object.

Overrides:

hashCode in class PublicKeyInfo

Returns:

the hash code

toString

public java.lang.String toString()

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

Overrides:

toString in class PublicKeyInfo

Returns:

the string representation