# Class SealedObject

java.lang.Object
javax.crypto.SealedObject

All Implemented Interfaces:
  `Serializable`

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.

Since:
  1.4
See Also:
  - `Cipher`
  - Serialized Form

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected byte[]`
  `encodedParams`
  The cryptographic parameters used by the sealing `Cipher` object, encoded in the default format.

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  ``
  `SealedObject(Serializable object, Cipher c)`
  Constructs a `SealedObject` from any `Serializable` object.
  `protected`
  `SealedObject(SealedObject so)`
  Constructs a `SealedObject` object from the passed-in `SealedObject`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `final String`
  `getAlgorithm()`
  Returns the algorithm that was used to seal this object.
  `final Object`
  `getObject(Key key)`
  Retrieves the original (encapsulated) object.
  `final Object`
  `getObject(Key key, String provider)`
  Retrieves the original (encapsulated) object.
  `final Object`
  `getObject(Cipher c)`
  Retrieves the original (encapsulated) object.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### encodedParams

    protected byte[] encodedParams
    The cryptographic parameters used by the sealing `Cipher` object, encoded in the default format.

    That is, `Cipher.getParameters().getEncoded()`.

- ## Constructor Details

  - ### SealedObject

    public SealedObject(Serializable object, Cipher c) throws IOException, IllegalBlockSizeException
    Constructs a `SealedObject` from any `Serializable` object.

    The given object is serialized, and its serialized contents are encrypted using the given `Cipher` object, which must be fully initialized.

    Any algorithm parameters that may be used in the encryption operation are stored inside the new `SealedObject`.

    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`.

- ## Method Details

  - ### 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
    Retrieves the original (encapsulated) object.

    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, a `Cipher` object 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.

    Parameters:
      `key` - the key used to unseal the object.
    Returns:
      the original object.
    Throws:
      `IOException` - if an error occurs during de-serialization.
      `ClassNotFoundException` - if an error occurs during de-serialization.
      `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
    Retrieves the original (encapsulated) object.

    The encapsulated object is unsealed (using the given `Cipher` object, assuming that the `Cipher` object is already properly initialized) and de-serialized, before it is returned.

    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-serialization
      `ClassNotFoundException` - if an error occurs during de-serialization
      `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
    Retrieves the original (encapsulated) object.

    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.

    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-serialization.
      `ClassNotFoundException` - if an error occurs during de-serialization.
      `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.