iaik.x509
Class PublicKeyInfo

java.lang.Object
  |
  +--iaik.x509.PublicKeyInfo

Direct Known Subclasses:

DHPublicKey, DSAPublicKey, RSAPublicKey

public abstract class PublicKeyInfo

extends java.lang.Object

implements ASN1Type, java.io.Serializable, PublicKey

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 the PKIX internet draft draft-ietf-pkix-ipki-part1-07:

 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, de- 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);
 

See Also:

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

Field Summary

protected AlgorithmID

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

Fields inherited from interface java.security.PublicKey

serialVersionUID

Fields inherited from interface java.security.Key

serialVersionUID

Constructor Summary

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

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 appertaining algorithm.
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 PublicKey	getPublicKey(ASN1Object publicKey) Creates a PublicKey from an ASN1Object.
static PublicKey	getPublicKey(byte[] publicKeyInfo) Creates a PublicKey from a DER encoded byte array.
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

clone, finalize, getClass, hashCode, 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 InvalidKeyException

Creates a new PublicKeyInfo from an ASN1Object.

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

Parameters:

obj - the PublicKeyInfo as ASN1Object

Throws:

InvalidKeyException - if the data can not be parsed

PublicKeyInfo

public PublicKeyInfo(java.io.InputStream is)
              throws 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:

InvalidKeyException - if the data can not be parsed

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

PublicKeyInfo

public PublicKeyInfo(byte[] arr)
              throws InvalidKeyException

Creates a new PublicKeyInfo from a DER byte array.

This constructor may be used for parsing an already exisiting 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:

InvalidKeyException - if the data can not be parsed

Method Detail

decode

protected abstract void decode(byte[] publicKey)
                        throws 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:

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 appertaining algorithm.

Returns:

the name of the algorithm

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 in the PKIX internet draft draft-ietf-pkix-ipki-part1-07:

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

getPublicKey

public static PublicKey getPublicKey(ASN1Object publicKey)
                              throws InvalidKeyException

Creates a PublicKey from an ASN1Object.

This is a static method and therefore may be called for creating a PublicKeyInfo from the given ASN1Object without explicitly instantiating this class, e.g:

 PublicKey pub_ki = PublicKeyInfo.getPublicKey(asn1_obj);
 

The given ASN1Object represents an already exisiting PrublicKeyInfo object, and may have been created by calling toASN1Object.

Parameters:

publicKey - the PublicKey as ASN1Object

Returns:

an instance of java.security.PublicKey, parsed from the supplied ASN1Object

Throws:

InvalidKeyException - if the ASN1Object cannot be parsed or the inherent AlgorithmID does not match to any implemented public-key algorithm

getPublicKey

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

Creates a PublicKey from a DER encoded byte array.

This is a static method and therefore may be called for creating a PublicKeyInfo from the given DER encoded ASN1Object without explicitly instantiating this class, e.g:

 PublicKey pub_key = PublicKeyInfo.getPublicKey(key_array);
 

The given DER encoded ASN1Object represents an already exisiting PublicKeyInfo object, and may have been created by calling getEncoded.

Parameters:

publicKeyInfo - the PublicKey as DER encoded byte array

Returns:

an instance of java.security.PublicKey, parsed from the supplied DER encoding

Throws:

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 der DER encoded version of the keys.

Overrides:

equals in class java.lang.Object

Returns:

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

getEncoded

public byte[] getEncoded()

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

Returns:

this PublicKeyInfo as DER encoded byte array

getFormat

public java.lang.String getFormat()

Returns the name of the encoding format.

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