PublicKeyInfo ("Entrust Authority Security Toolkit for the Java Platform")

java.lang.Object
- iaik.x509.PublicKeyInfo

All Implemented Interfaces:

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

Direct Known Subclasses:

DHPublicKey, DSAPublicKey, ECDSAPublicKey, EcOriginatorPublicKey, EcPublicKey, ESDHPublicKey, RSAPublicKey, WrappedPublicKey
```
public abstract class PublicKeyInfo
extends java.lang.Object
implements ASN1Type, java.io.Serializable, java.security.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 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, 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

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.

Fields inherited from interface java.security.PublicKey
serialVersionUID

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

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`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 java.security.PublicKey`	`getPublicKey(ASN1Object publicKey)` Creates a PublicKey from an ASN1Object.
`static java.security.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 java.security.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:
    
    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 appertaining algorithm.
    
    Specified by:
    
    getAlgorithm in interface java.security.Key
    
    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 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 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:
    
    java.security.InvalidKeyException - if the ASN1Object cannot be parsed or the inherent AlgorithmID does not match to any implemented public-key algorithm
  - getPublicKey
```
public static java.security.PublicKey getPublicKey(byte[] publicKeyInfo)
                                            throws java.security.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:
    
    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 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.
    
    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

Class PublicKeyInfo

Field Summary

Fields inherited from interface java.security.PublicKey

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

public_key_algorithm

Constructor Detail

PublicKeyInfo

PublicKeyInfo

PublicKeyInfo

PublicKeyInfo

Method Detail

decode

encode

getAlgorithm

decode

createPublicKeyInfo

getPublicKey

getPublicKey

toASN1Object

equals

getEncoded

getFormat

getFingerprint

writeTo

toString