iaik.x509

Class PublicKeyInfo

java.lang.Object

iaik.x509.PublicKeyInfo

All Implemented Interfaces:

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

Direct Known Subclasses:

DHPublicKey, DSAPublicKey, ElGamalPublicKey, RawPublicKey, RSAPublicKey

public abstract class PublicKeyInfo
extends java.lang.Object
implements ASN1Type, java.security.PublicKey, java.lang.Cloneable

This class implements a PublicKeyInfo as used within X.509 certificates for representing the subject's public key in the SubjectPublicKeyInfo field. The subject is the entity claiming for certification of its public key. The subject's public key is of type subjectPublicKeyInfo including a BIT-STRING representation of the public key together with an identification of the public-key algorithm being used, as defined in RFC 3280:

 SubjectPublicKeyInfo  ::=  SEQUENCE  {
   algorithm            AlgorithmIdentifier,
   subjectPublicKey     BIT STRING  }
 

where:

 AlgorithmIdentifier  ::=  SEQUENCE  {
   algorithm               OBJECT IDENTIFIER,
   parameters              ANY DEFINED BY algorithm OPTIONAL  }
 
 

This class has to be extended by any class implementing some particular public key (e.g. RSAPublicKey, DSAPublicKey, DHPublicKey) for being used within the X.509 certificate environment.

This class provides a variety of methods for creating, parsing, decoding and encoding public key informations.

As an example, for creating an instance of java.security.PublicKey from an ASN1Object representation, or a DER encoding, use the static getPublicKey(ASN1Object) respectively getPublicKey(byte[]) methods, e.g.:

 byte[] encoding = ...;
 PublicKey publicKey = PublicKeyInfo(encoding);
 

Version:

File Revision 30

See Also:

X509Certificate, RSAPublicKey, DSAPublicKey, DHPublicKey, AlgorithmID, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected AlgorithmID	public_key_algorithm The algorithm identifier of the public key algorithm belonging to the particular public key implemeting this PublicKeyInfo.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	PublicKeyInfo() Default Constructor for derived classes.
	PublicKeyInfo(ASN1Object obj) Creates a new PublicKeyInfo from an ASN1Object.
	PublicKeyInfo(byte[] arr) Creates a new PublicKeyInfo from a DER byte array.
	PublicKeyInfo(java.io.InputStream is) Creates a new PublicKeyInfo from an InputStream.

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	clone() Return a clone of this private key object.
protected void	createPublicKeyInfo() Creates a PublicKeyInfo data structure (X.509).
void	decode(ASN1Object obj) Decodes the given ASN.1 PublicKeyInfo object for parsing the internal structure.
protected abstract void	decode(byte[] publicKey) Abstract method to be implemented for decoding a DER encoded public key.
protected abstract byte[]	encode() Abstract method to be implemented for DER encoding the particular public key extending this PublicKeyInfo.
boolean	equals(java.lang.Object obj) Compares this public key to another public key.
abstract java.lang.String	getAlgorithm() Returns the name of the key algorithm.
AlgorithmID	getAlgorithmID() Returns the key algorithm id.
byte[]	getEncoded() Returns this PublicKeyInfo as a DER encoded ASN.1 data structure.
byte[]	getFingerprint() Returns a fingerprint of the public key.
java.lang.String	getFormat() Returns the name of the encoding format.
static java.security.PublicKey	getPublicKey(ASN1Object publicKey) Creates a PublicKey from an ASN1Object.
static java.security.PublicKey	getPublicKey(ASN1Object publicKey, java.security.Provider provider) Creates a PublicKey of the given provider from an ASN1Object.
static java.security.PublicKey	getPublicKey(ASN1Object publicKey, java.lang.String providerName) Creates a PublicKey of the given provider from an ASN1Object.
static java.security.PublicKey	getPublicKey(byte[] publicKeyInfo) Creates a PublicKey from a DER encoded byte array.
static java.security.PublicKey	getPublicKey(byte[] publicKeyInfo, java.security.Provider provider) Creates a PublicKey of the given provider from a DER encoded byte array.
static java.security.PublicKey	getPublicKey(byte[] publicKeyInfo, java.lang.String providerName) Creates a PublicKey of the given provider from a DER encoded byte array.
int	hashCode() Returns a hash code for this object.
ASN1Object	toASN1Object() Returns this PublicKeyInfo as ASN1Object.
java.lang.String	toString() Returns a string that represents the contents of this public key.
void	writeTo(java.io.OutputStream os) Writes this public key to an output stream.

Methods inherited from class java.lang.Object

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

Field Detail

public_key_algorithm

protected AlgorithmID public_key_algorithm

The algorithm identifier of the public key algorithm belonging to the particular public key implemeting this PublicKeyInfo.

Constructor Detail

PublicKeyInfo

protected PublicKeyInfo()

Default Constructor for derived classes.

PublicKeyInfo

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

Creates a new PublicKeyInfo from an ASN1Object.

This constructor may be used for parsing an already existing PublicKeyInfo object, supplied as ASN1Object that may have been created by calling toASN1Object.

Parameters:

obj - the PublicKeyInfo as ASN1Object

Throws:

java.security.InvalidKeyException - if the data can not be parsed

PublicKeyInfo

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

Creates a new PublicKeyInfo from an InputStream.

This constructor reads a DER or PEM encoded PublicKeyInfo which previously may have been written with method writeTo(OutputStream). This constructor cannot be used to read a serialized object.

Parameters:

is - the input stream from where the encoded PublicKeyInfo shall be read

Throws:

java.security.InvalidKeyException - if the data can not be parsed

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

PublicKeyInfo

public PublicKeyInfo(byte[] arr)
              throws java.security.InvalidKeyException

Creates a new PublicKeyInfo from a DER byte array.

This constructor may be used for parsing an already existing PublicKeyInfo ASN1 object, supplied as DER encoded byte array, which may have been created by calling the getEncoded method.

Parameters:

arr - the array containing the encoded PublicKeyInfo

Throws:

java.security.InvalidKeyException - if the data can not be parsed

Method Detail

decode

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

Abstract method to be implemented for decoding a DER encoded public key.

Parameters:

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

Throws:

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

encode

protected abstract byte[] encode()

Abstract method to be implemented for DER encoding the particular public key extending this PublicKeyInfo.

Returns:

a byte array holding the public key implementation as a DER encoded ASN.1 datastructure

getAlgorithm

public abstract java.lang.String getAlgorithm()

Returns the name of the key algorithm.

Specified by:

getAlgorithm in interface java.security.Key

Returns:

the name of the key algorithm

getAlgorithmID

public AlgorithmID getAlgorithmID()

Returns the key algorithm id.

Returns:

the key algorithm id

clone

public java.lang.Object clone()

Return a clone of this private key object.

Overrides:

clone in class java.lang.Object

Returns:

A clone of this private key object.

decode

public void decode(ASN1Object obj)
            throws CodingException

Decodes the given ASN.1 PublicKeyInfo object for parsing the internal structure.

This method implements the ASN1Type interface.

Specified by:

decode in interface ASN1Type

Parameters:

obj - the PublicKeyInfo as ASN1Object

Throws:

CodingException - if the ASN1Object could not be parsed

createPublicKeyInfo

protected void createPublicKeyInfo()

Creates a PublicKeyInfo data structure (X.509).

This method is called by extending classes for creating a PublicKeyInfo. This method creates a PublicKeyInfo as an ASN.1 SEQUENCE object with components as specified in RFC 3280:

 SubjectPublicKeyInfo ::=  SEQUENCE  {
   algorithm            AlgorithmIdentifier,
   subjectPublicKey     BIT STRING  }
 

getPublicKey

public static java.security.PublicKey getPublicKey(ASN1Object publicKey)
                                            throws java.security.InvalidKeyException

Creates a PublicKey from an ASN1Object.

This method tries to instantiate a KeyFactory for the key algorithm. If no KeyFactory is available a generic public key is created allowing to get some information about the key (algorithm, encoding).

Parameters:

publicKey - the X.509 PublicKey as ASN1Object

Returns:

an instance of java.security.PublicKey, parsed from the supplied ASN1Object; if no KeyFactory is available for the key algorithm a RawPublicKey object is returned

Throws:

java.security.InvalidKeyException - if the ASN1Object cannot be parsed

getPublicKey

public static java.security.PublicKey getPublicKey(ASN1Object publicKey,
                                   java.lang.String providerName)
                                            throws java.security.InvalidKeyException

Creates a PublicKey of the given provider from an ASN1Object.

This method tries to instantiate a KeyFactory for the key algorithm. If no KeyFactory is available a generic public key is created allowing to get some information about the key (algorithm, encoding).

Parameters:

publicKey - the PublicKey as ASN1Object

providerName - the name of the provider from which to get a PublicKey object

Returns:

an instance of java.security.PublicKey, parsed from the supplied ASN1Object; if no KeyFactory is available for the key algorithm a RawPublicKey object is returned

Throws:

java.security.InvalidKeyException - if the ASN1Object cannot be parsed

getPublicKey

public static java.security.PublicKey getPublicKey(ASN1Object publicKey,
                                   java.security.Provider provider)
                                            throws java.security.InvalidKeyException

Creates a PublicKey of the given provider from an ASN1Object.

This method tries to instantiate a KeyFactory for the key algorithm. If no KeyFactory is available a generic public key is created allowing to get some information about the key (algorithm, encoding).

If Provider object based JCA/JCE KeyFactory engine instantiation is not available the Java VM in use (<1.4), this method tries to instantiate an implementation based on the provider name (if the Provider is installed within the Security Provider framework). I.e. if method KeyFactory.getInstance(algorithm,provider) is not available method KeyFactory.getInstance(algorithm,provider.getName()) is tried.

Parameters:

publicKey - the PublicKey as ASN1Object

provider - the provider from which to get a PublicKey object

Returns:

an instance of java.security.PublicKey, parsed from the supplied ASN1Object; if no KeyFactory is available for the key algorithm a RawPublicKey object is returned

Throws:

java.security.InvalidKeyException - if the ASN1Object cannot be parsed

getPublicKey

public static java.security.PublicKey getPublicKey(byte[] publicKeyInfo)
                                            throws java.security.InvalidKeyException

Creates a PublicKey from a DER encoded byte array.

This method tries to instantiate a KeyFactory for the key algorithm. If no KeyFactory is available a generic public key is created allowing to get some information about the key (algorithm, encoding).

Parameters:

publicKeyInfo - the PublicKey as DER encoded byte array

Returns:

an instance of java.security.PublicKey, parsed from the supplied DER encoding; if no KeyFactory is available for the key algorithm a RawPublicKey object is returned

Throws:

java.security.InvalidKeyException - if the publicKeyInfo cannot be parsed

getPublicKey

public static java.security.PublicKey getPublicKey(byte[] publicKeyInfo,
                                   java.lang.String providerName)
                                            throws java.security.InvalidKeyException

Creates a PublicKey of the given provider from a DER encoded byte array.

This method tries to instantiate a KeyFactory for the key algorithm. If no KeyFactory is available a generic public key is created allowing to get some information about the key (algorithm, encoding).

Parameters:

publicKeyInfo - the PublicKey as DER encoded byte array

providerName - the name of the provider from which to get a PublicKey object

Returns:

an instance of java.security.PublicKey, parsed from the supplied DER encoding; if no KeyFactory is available for the key algorithm a RawPublicKey object is returned

Throws:

java.security.InvalidKeyException - if the publicKeyInfo cannot be parsed

getPublicKey

public static java.security.PublicKey getPublicKey(byte[] publicKeyInfo,
                                   java.security.Provider provider)
                                            throws java.security.InvalidKeyException

Creates a PublicKey of the given provider from a DER encoded byte array.

This method tries to instantiate a KeyFactory for the key algorithm. If no KeyFactory is available a generic public key is created allowing to get some information about the key (algorithm, encoding).

If Provider object based JCA/JCE KeyFactory engine instantiation is not available the Java VM in use (<1.4), this method tries to instantiate an implementation based on the provider name (if the Provider is installed within the Security Provider framework). I.e. if method KeyFactory.getInstance(algorithm,provider) is not available method KeyFactory.getInstance(algorithm,provider.getName()) is tried.

Parameters:

publicKeyInfo - the PublicKey as DER encoded byte array

provider - the provider from which to get a PublicKey object

Returns:

an instance of java.security.PublicKey, parsed from the supplied DER encoding; if no KeyFactory is available for the key algorithm a RawPublicKey object is returned

Throws:

java.security.InvalidKeyException - if the publicKeyInfo cannot be parsed

toASN1Object

public ASN1Object toASN1Object()

Returns this PublicKeyInfo as ASN1Object.

Specified by:

toASN1Object in interface ASN1Type

Returns:

this PublicKeyInfo as ASN1Object

equals

public boolean equals(java.lang.Object obj)

Compares this public key to another public key. This method simply compares the DER encoded versions of the keys.

Overrides:

equals in class java.lang.Object

Returns:

true, if the 2 public keys are equal, false otherwise

hashCode

public int hashCode()

Returns a hash code for this object.

Overrides:

hashCode in class java.lang.Object

Returns:

the hash code

getEncoded

public byte[] getEncoded()

Returns this PublicKeyInfo as a DER encoded ASN.1 data structure.

Specified by:

getEncoded in interface java.security.Key

Returns:

this PublicKeyInfo as DER encoded byte array

getFormat

public java.lang.String getFormat()

Returns the name of the encoding format.

Specified by:

getFormat in interface java.security.Key

Returns:

the string "X.509"

getFingerprint

public byte[] getFingerprint()

Returns a fingerprint of the public key. This method only computes a MD5 hash over the DER encoded public key.

Returns:

a fingerprint of the public key

writeTo

public void writeTo(java.io.OutputStream os)
             throws java.io.IOException

Writes this public key to an output stream.

Parameters:

os - the output stream

Throws:

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

toString

public java.lang.String toString()

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

Overrides:

toString in class java.lang.Object

Returns:

the string representation