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java.lang.Object | +----javax.crypto.SealedObject
Given any Serializable object, one can create a SealedObject that encapsulates the original object, in serialised format (i.e., a "deep copy"), and seals (encrypts) its serialised contents, using a cryptographic algorithm such as DES, to protect its confidentiality. The encrypted content can later be decrypted (with the corresponding algorithm using the correct decryption key) and de-serialised, yielding the original object.
Note that the Cipher object must be fully initialised 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 initialised Cipher object, initialised 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 initialised 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 get Object methods that take a Key object.
In this approach, the getObject method creates a cipher object for the appropriate decryption algorithm and initialises 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.
public SealedObject(Serializable object, Cipher c) throws IOException, IllegalBlockSizeException
The given object is sealed using the given Cipher, assuming that the Cipher is already properly initialised.
Any algorithm parameters that may be used in the encryption operation are stored inside of the new SealedObject.
public final String getAlgorithm()
public final Object getObject(Key key) throws IOException, ClassNotFoundException, NoSuchAlgorithmException, InvalidKeyException
This method creates a cipher for the algorithm that had been used in the sealing operation. If the default provider package provides an implementation of that algorithm, an instance of Cipher containing that implementation is used. If the algorithm is not available in the default package, other packages are searched. The Cipher object is initialised for decryption, using the given key and the parameters (if any) that had been used in the sealing operation.
The encapsulated object is unsealed and de-serialised, before it is returned.
public final Object getObject(Cipher c) throws IOException, ClassNotFoundException, IllegalBlockSizeException, BadPaddingException
The encapsulated object is unsealed (using the given Cipher, assuming that the Cipher is already properly initialised) and de-serialised, before it is returned.
public final Object getObject(Key key, String provider) throws IOException, ClassNotFoundException, NoSuchAlgorithmException, NoSuchProviderException, InvalidKeyException
This method creates a cipher for the algorithm that had been used in the sealing operation, using an implementation of that algorithm from the given provider. The Cipher object is initialised for decryption, using the given key and the parameters (if any) that had been used in the sealing operation.
The encapsulated object is unsealed and de-serialised, before it is returned.
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