iaik.asn1

Class EncodedASN1Object

java.lang.Object

iaik.asn1.ASN1Object

iaik.asn1.EncodedASN1Object

All Implemented Interfaces:

java.lang.Cloneable

public class EncodedASN1Object
extends ASN1Object

This class represents an utility for handling encoded ASN.1 object within the IAIK ASN.1 framework.
This class allows to incorporate a given DER encoding into an ASN.1 object without the necessity of decoding it. This may be useful in situations where an structured ASN.1 object shall be encoded and one of its components already is given in encoded format. The encoding may be supplied either as byte array or from an input stream; the latter may be preferable when dealing with large encodings. Consider for instance an already encoded SEQUENCE object to be set as the second component of a new two-component SEQUENCE object:

 mySequence ::= SEQUENCE {   
   firstComponent INTEGER,    
   secondComponent SEQUENCE }
 

Normally you would have to decode the SEQUENCE before adding it to the new SEQUENCE type:

 SEQUENCE mySequence = new SEQUENCE();
   mySequence.addComponent(new INTEGER(2));
   mySequence.addComponent(DerCoder.decode(encodedSequence));
 

The code sample above may appear as part of an toASN1Object method for giving an ASN.1 representation of an Java object to be fed immediately to the DerCoder encoding utility:

 byte[] encoding = DerCoder.encode(myASN1Class.toASN1Object());
 

Now, with class EncodedASN1Object you may avoid the decoding-encoding step by immediately supplying the encoded SEQUENCE component:

 SEQUENCE mySequence = new SEQUENCE();
   mySequence.addComponent(new INTEGER(2));
   mySequence.addComponent(new EncodedASN1Object(encodedSequence));
 

When now calling the DerCoder, the second component is encoded by only "copying" the already given encoding.

Attention! This class only should be used very carefully and only for a purpose as described above. This class only provides very limited access to the ASN.1 functionalities accustomed from the other ASN.1 types of this packages. So, for instance, it does not have a tag number associated to it and it does not provide any decoding enhancements. This class provides nothing more than some kind of piping mechanism: the encoded bytes supplied by one of the constructures are written ("copied") unchanged to the supplied OutputStream when the DerCoder calls the encode method.

See Also:

ASN1Object, ASN, ConstructedType, DerCoder

Field Summary

Fields inherited from class iaik.asn1.ASN1Object

asnType, constructed, encode_listener, indefinite_length, isStringType, stream_mode

Constructor Summary

Constructors

Constructor and Description
EncodedASN1Object() Creates an empty EncodedASN1Object.
EncodedASN1Object(byte[] encodedASN1Object) Creates an EncodedASN1Object object where the encoding is supplied from an byte array.
EncodedASN1Object(java.io.InputStream encodedStream) Creates an EncodedASN1Object object where the encoding is supplied from an input stream.
EncodedASN1Object(java.io.InputStream encodedStream, int blockSize) Creates an EncodedASN1Object object which reads the encoding from an InputStream and processes it into blocks of blockSize bytes.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	decode(int length, java.io.InputStream is) Only throws a CodingException since decoding not supported by this class.
protected void	encode(java.io.OutputStream os) Writes this EncodedASN1Object to the given output stream.
int	getBlockSize() Returns the blockSize defining the number of bytes to be processed in memory.
java.lang.Object	getValue() Returns the encoded ASN.1 object itself.
void	setIndefiniteLength(boolean indefiniteLength) Does nothing.
void	setValue(java.lang.Object object) Sets the value of this object.
java.lang.String	toString() Returns a string representation of this object.

Methods inherited from class iaik.asn1.ASN1Object

addComponent, addEncodeListener, clone, countComponents, encodeObject, getAsnType, getComponentAt, indefiniteLength, isA, isConstructed, isStringType

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

EncodedASN1Object

public EncodedASN1Object()

Creates an empty EncodedASN1Object. Shall not be used by an application.

EncodedASN1Object

public EncodedASN1Object(byte[] encodedASN1Object)

Creates an EncodedASN1Object object where the encoding is supplied from an byte array. This constructor does not decode the given encoded ASN.1 object! It only maintains the given encoding to be written out when the DerCoder is invoked.

Parameters:

encodedASN1Object - an encoded ASN.1 object supplied from a byte array

EncodedASN1Object

public EncodedASN1Object(java.io.InputStream encodedStream)

Creates an EncodedASN1Object object where the encoding is supplied from an input stream. This constructor does not decode the given encoded ASN.1 object! It only maintains the given encoding to be written out when the DerCoder is invoked.

Parameters:

encodedStream - an encoded ASN.1 object supplied from an input stream

EncodedASN1Object

public EncodedASN1Object(java.io.InputStream encodedStream,
                 int blockSize)

Creates an EncodedASN1Object object which reads the encoding from an InputStream and processes it into blocks of blockSize bytes. This constructor does not decode the given encoded ASN.1 object! It only maintains the given encoding to be written out when the DerCoder is invoked.

Parameters:

encodedStream - an encoded ASN.1 object supplied from an input stream

blockSize - the blocksize setting the block size for in-memory processing

Method Detail

getValue

public java.lang.Object getValue()

Returns the encoded ASN.1 object itself.

Specified by:

getValue in class ASN1Object

Returns:

the encoded ASN.1 object as byte array or input stream.

setValue

public void setValue(java.lang.Object object)

Sets the value of this object.

The value may be supplied as byte array or input stream and represents the encoding of the ASN1Object.

Generally there should be no need for using this method since data immediately can be supplied when creating a new simple OCTET_STRING object by means of a proper constructor.

Specified by:

setValue in class ASN1Object

Parameters:

object - the value (encoding), as byte array or input stream

setIndefiniteLength

public void setIndefiniteLength(boolean indefiniteLength)

Does nothing.

Overrides:

setIndefiniteLength in class ASN1Object

Parameters:

indefiniteLength - ignored

encode

protected void encode(java.io.OutputStream os)
               throws java.io.IOException

Writes this EncodedASN1Object to the given output stream. This is a protected method and will not be used by an application for DER encoding an EncodedASN1Object object. An application will call one of the encode methods of the DerCoder class for performing the encoding, and the DerCoder internally will call this encode method.

Specified by:

encode in class ASN1Object

Parameters:

os - the output stream to which to write the encoding

Throws:

java.io.IOException - if an error occurs during writing to the stream

decode

protected void decode(int length,
          java.io.InputStream is)
               throws CodingException

Only throws a CodingException since decoding not supported by this class.

Specified by:

decode in class ASN1Object

Parameters:

length - the already decoded length, i.e. number of the bytes representing the ASN1Object to be decoded

is - the InputStream supplying the encoded ASN1Object

Throws:

java.io.IOException - if there is a problem with the InputStream

CodingException - since not supported by this class

getBlockSize

public int getBlockSize()

Returns the blockSize defining the number of bytes to be processed in memory.

Returns:

the block size

toString

public java.lang.String toString()

Returns a string representation of this object.

Overrides:

toString in class ASN1Object

Returns:

the string representation