javax.crypto.SealedObject
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java.lang.Object
public class SealedObject
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 DES, 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:
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.
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.
| Field Summary | |
|---|---|
private String |
algorithm_
The algorithm that was used to seal the object. |
private byte[] |
data_
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private String |
pAlg_
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private byte[] |
params_
The encoded paramaters. |
private static long |
serialVersionUID
Use serialVersionUID for interoperability. |
| Constructor Summary | |
|---|---|
SealedObject(Serializable object,
Cipher cipher)
Constructs a SealedObject from any Serializable object. |
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| Method Summary | |
|---|---|
String |
getAlgorithm()
Returns the algorithm that was used to seal this object. |
Object |
getObject(Cipher cipher)
Retrieves the original (encapsulated) object. |
Object |
getObject(Key key)
Retrieves the original (encapsulated) object. |
Object |
getObject(Key key,
String provider)
Retrieves the original (encapsulated) object. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
|---|
private static final long serialVersionUID
private byte[] params_
private String pAlg_
private String algorithm_
private byte[] data_
| Constructor Detail |
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public SealedObject(Serializable object,
Cipher cipher)
throws IOException,
IllegalBlockSizeException
The given object is serialized, and its serialized contents are encrypted using the given Cipher, which must be fully initialized.
Any algorithm parameters that may be used in the encryption
operation are stored inside of the new SealedObject.
object - the object to be sealed; can be null.cipher - the cipher used to seal the object.
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.
NullPointerException - if the given cipher is null.| Method Detail |
|---|
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
initialized 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-serialized, before it is returned.
key - the key used to unseal the object.
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).
public final Object getObject(Cipher cipher)
throws IOException,
ClassNotFoundException,
IllegalBlockSizeException,
BadPaddingException
The encapsulated object is unsealed (using the given Cipher, assuming that the Cipher is already properly initialized) and de-serialized, before it is returned.
cipher - the cipher used to unseal the object
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.
NullPointerException - if the given cipher is null.
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 initialized
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-serialized, before it is returned.
key - the key used to unseal the object.provider - the name of the provider of the algorithm to unseal
the object.
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).
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