Class SealedObject

public class SealedObject
extends Object
implements Serializable

This class enables a programmer to create an object and protect its confidentiality with a cryptographic algorithm.

Given any Serializable object, one can create a SealedObject that encapsulates the original object, in serialized format (i.e., a "deep copy"), and seals (encrypts) its serialized contents, using a cryptographic algorithm such as AES, to protect its confidentiality. The encrypted content can later be decrypted (with the corresponding algorithm using the correct decryption key) and de-serialized, yielding the original object.

Note that the Cipher object must be fully initialized with the correct algorithm, key, padding scheme, etc., before being applied to a SealedObject.

The original object that was sealed can be recovered in two different ways:

• by using the getObject method that takes a Cipher object.

  This method requires a fully initialized Cipher object, initialized with the exact same algorithm, key, padding scheme, etc., that were used to seal the object.

  This approach has the advantage that the party who unseals the sealed object does not require knowledge of the decryption key. For example, after one party has initialized the cipher object with the required decryption key, it could hand over the cipher object to another party who then unseals the sealed object.

• by using one of the getObject methods that take a Key object.

  In this approach, the getObject method creates a cipher object for the appropriate decryption algorithm and initializes it with the given decryption key and the algorithm parameters (if any) that were stored in the sealed object.

  This approach has the advantage that the party who unseals the object does not need to keep track of the parameters (e.g., an IV) that were used to seal the object.

Fields

encodedParams

protected byte[] encodedParams

Constructors

SealedObject

public SealedObject(Serializable object,
                    Cipher c)
             throws IOException,
                    IllegalBlockSizeException

Parameters:

object - the object to be sealed; can be null.

c - the cipher used to seal the object.

Throws:

NullPointerException - if the given cipher is null.

IOException - if an error occurs during serialization

IllegalBlockSizeException - if the given cipher is a block cipher, no padding has been requested, and the total input length (i.e., the length of the serialized object contents) is not a multiple of the cipher's block size

SealedObject

protected SealedObject(SealedObject so)

Constructs a SealedObject object from the passed-in SealedObject.

Parameters:

so - a SealedObject object

Throws:

NullPointerException - if the given sealed object is null.

Methods

getAlgorithm

public final String getAlgorithm()

Returns the algorithm that was used to seal this object.

Returns:

the algorithm that was used to seal this object.

getObject

public final Object getObject(Key key)
                       throws IOException,
                              ClassNotFoundException,
                              NoSuchAlgorithmException,
                              InvalidKeyException

Parameters:

key - the key used to unseal the object.

Returns:

the original object.

Throws:

IOException - if an error occurs during de-serialiazation.

ClassNotFoundException - if an error occurs during de-serialiazation.

NoSuchAlgorithmException - if the algorithm to unseal the object is not available.

InvalidKeyException - if the given key cannot be used to unseal the object (e.g., it has the wrong algorithm).

NullPointerException - if key is null.

getObject

public final Object getObject(Cipher c)
                       throws IOException,
                              ClassNotFoundException,
                              IllegalBlockSizeException,
                              BadPaddingException

Parameters:

c - the cipher used to unseal the object

Returns:

the original object.

Throws:

NullPointerException - if the given cipher is null.

IOException - if an error occurs during de-serialiazation

ClassNotFoundException - if an error occurs during de-serialiazation

IllegalBlockSizeException - if the given cipher is a block cipher, no padding has been requested, and the total input length is not a multiple of the cipher's block size

BadPaddingException - if the given cipher has been initialized for decryption, and padding has been specified, but the input data does not have proper expected padding bytes

getObject

public final Object getObject(Key key,
                              String provider)
                       throws IOException,
                              ClassNotFoundException,
                              NoSuchAlgorithmException,
                              NoSuchProviderException,
                              InvalidKeyException

Parameters:

key - the key used to unseal the object.

provider - the name of the provider of the algorithm to unseal the object.

Returns:

the original object.

Throws:

IllegalArgumentException - if the given provider is null or empty.

IOException - if an error occurs during de-serialiazation.

ClassNotFoundException - if an error occurs during de-serialiazation.

NoSuchAlgorithmException - if the algorithm to unseal the object is not available.

NoSuchProviderException - if the given provider is not configured.

InvalidKeyException - if the given key cannot be used to unseal the object (e.g., it has the wrong algorithm).

NullPointerException - if key is null.