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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package javax.crypto;

import java.util.StringTokenizer;
import java.util.NoSuchElementException;
import java.security.AlgorithmParameters;
import java.security.Provider;
import java.security.Key;
import java.security.SecureRandom;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.InvalidKeyException;
import java.security.InvalidAlgorithmParameterException;
import java.security.ProviderException;
import java.security.spec.AlgorithmParameterSpec;

import java.nio.ByteBuffer;

This class defines the Service Provider Interface (SPI)
for the Cipher class.
All the abstract methods in this class must be implemented by each
cryptographic service provider who wishes to supply the implementation
of a particular cipher algorithm.
In order to create an instance of Cipher, which
encapsulates an instance of this CipherSpi class, an application calls one of the getInstance factory methods of the Cipher engine class and specifies the requested transformation.
Optionally, the application may also specify the name of a provider.
A transformation is a string that describes the operation (or
set of operations) to be performed on the given input, to produce some
output. A transformation always includes the name of a cryptographic
algorithm (e.g., AES), and may be followed by a feedback mode and
padding scheme.
 A transformation is of the form:

"algorithm/mode/padding" or
"algorithm"

 (in the latter case,
provider-specific default values for the mode and padding scheme are used).
For example, the following is a valid transformation:
    Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");

A provider may supply a separate class for each combination
of algorithm/mode/padding, or may decide to provide more generic
classes representing sub-transformations corresponding to
algorithm or algorithm/mode or algorithm//padding
(note the double slashes),
in which case the requested mode and/or padding are set automatically by
the getInstance methods of Cipher, which invoke the engineSetMode and engineSetPadding methods of the provider's subclass of CipherSpi.
A Cipher property in a provider master class may have one of
the following formats:


    // provider's subclass of "CipherSpi" implements "algName" with
    // pluggable mode and padding
    Cipher.algName


    // provider's subclass of "CipherSpi" implements "algName" in the
    // specified "mode", with pluggable padding
    Cipher.algName/mode


    // provider's subclass of "CipherSpi" implements "algName" with the
    // specified "padding", with pluggable mode
    Cipher.algName//padding


    // provider's subclass of "CipherSpi" implements "algName" with the
    // specified "mode" and "padding"
    Cipher.algName/mode/padding


For example, a provider may supply a subclass of CipherSpi
that implements AES/ECB/PKCS5Padding, one that implements
AES/CBC/PKCS5Padding, one that implements
AES/CFB/PKCS5Padding, and yet another one that implements
AES/OFB/PKCS5Padding. That provider would have the following
Cipher properties in its master class:


    Cipher.AES/ECB/PKCS5Padding


    Cipher.AES/CBC/PKCS5Padding


    Cipher.AES/CFB/PKCS5Padding


    Cipher.AES/OFB/PKCS5Padding


Another provider may implement a class for each of the above modes
(i.e., one class for ECB, one for CBC, one for CFB,
and one for OFB), one class for PKCS5Padding,
and a generic AES class that subclasses from CipherSpi.
That provider would have the following
Cipher properties in its master class:


    Cipher.AES


The getInstance factory method of the Cipher
engine class follows these rules in order to instantiate a provider's
implementation of CipherSpi for a
transformation of the form "algorithm":


Check if the provider has registered a subclass of CipherSpi
for the specified "algorithm".
If the answer is YES, instantiate this
class, for whose mode and padding scheme default values (as supplied by
the provider) are used.
If the answer is NO, throw a NoSuchAlgorithmException
exception.

The getInstance factory method of the Cipher
engine class follows these rules in order to instantiate a provider's
implementation of CipherSpi for a
transformation of the form "algorithm/mode/padding":


Check if the provider has registered a subclass of CipherSpi
for the specified "algorithm/mode/padding" transformation.
If the answer is YES, instantiate it.
If the answer is NO, go to the next step.

Check if the provider has registered a subclass of CipherSpi
for the sub-transformation "algorithm/mode".
If the answer is YES, instantiate it, and call
engineSetPadding(padding) on the new instance.
If the answer is NO, go to the next step.

Check if the provider has registered a subclass of CipherSpi
for the sub-transformation "algorithm//padding" (note the double
slashes).
If the answer is YES, instantiate it, and call
engineSetMode(mode) on the new instance.
If the answer is NO, go to the next step.

Check if the provider has registered a subclass of CipherSpi
for the sub-transformation "algorithm".
If the answer is YES, instantiate it, and call
engineSetMode(mode) and
engineSetPadding(padding) on the new instance.
If the answer is NO, throw a NoSuchAlgorithmException
exception.

Author:
Jan Luehe
See Also:
KeyGenerator
SecretKey
Since:
1.4/**
 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
 * for the <code>Cipher</code> class.
 * All the abstract methods in this class must be implemented by each
 * cryptographic service provider who wishes to supply the implementation
 * of a particular cipher algorithm.
 *
 * <p>In order to create an instance of <code>Cipher</code>, which
 * encapsulates an instance of this <code>CipherSpi</code> class, an
 * application calls one of the
 * {@link Cipher#getInstance(java.lang.String) getInstance}
 * factory methods of the
 * {@link Cipher Cipher} engine class and specifies the requested
 * <i>transformation</i>.
 * Optionally, the application may also specify the name of a provider.
 *
 * <p>A <i>transformation</i> is a string that describes the operation (or
 * set of operations) to be performed on the given input, to produce some
 * output. A transformation always includes the name of a cryptographic
 * algorithm (e.g., <i>AES</i>), and may be followed by a feedback mode and
 * padding scheme.
 *
 * <p> A transformation is of the form:
 *
 * <ul>
 * <li>"<i>algorithm/mode/padding</i>" or
 *
 * <li>"<i>algorithm</i>"
 * </ul>
 *
 * <P> (in the latter case,
 * provider-specific default values for the mode and padding scheme are used).
 * For example, the following is a valid transformation:
 *
 * <pre>
 *     Cipher c = Cipher.getInstance("<i>AES/CBC/PKCS5Padding</i>");
 * </pre>
 *
 * <p>A provider may supply a separate class for each combination
 * of <i>algorithm/mode/padding</i>, or may decide to provide more generic
 * classes representing sub-transformations corresponding to
 * <i>algorithm</i> or <i>algorithm/mode</i> or <i>algorithm//padding</i>
 * (note the double slashes),
 * in which case the requested mode and/or padding are set automatically by
 * the <code>getInstance</code> methods of <code>Cipher</code>, which invoke
 * the {@link #engineSetMode(java.lang.String) engineSetMode} and
 * {@link #engineSetPadding(java.lang.String) engineSetPadding}
 * methods of the provider's subclass of <code>CipherSpi</code>.
 *
 * <p>A <code>Cipher</code> property in a provider master class may have one of
 * the following formats:
 *
 * <ul>
 *
 * <li>
 * <pre>
 *     // provider's subclass of "CipherSpi" implements "algName" with
 *     // pluggable mode and padding
 *     <code>Cipher.</code><i>algName</i>
 * </pre>
 *
 * <li>
 * <pre>
 *     // provider's subclass of "CipherSpi" implements "algName" in the
 *     // specified "mode", with pluggable padding
 *     <code>Cipher.</code><i>algName/mode</i>
 * </pre>
 *
 * <li>
 * <pre>
 *     // provider's subclass of "CipherSpi" implements "algName" with the
 *     // specified "padding", with pluggable mode
 *     <code>Cipher.</code><i>algName//padding</i>
 * </pre>
 *
 * <li>
 * <pre>
 *     // provider's subclass of "CipherSpi" implements "algName" with the
 *     // specified "mode" and "padding"
 *     <code>Cipher.</code><i>algName/mode/padding</i>
 * </pre>
 *
 * </ul>
 *
 * <p>For example, a provider may supply a subclass of <code>CipherSpi</code>
 * that implements <i>AES/ECB/PKCS5Padding</i>, one that implements
 * <i>AES/CBC/PKCS5Padding</i>, one that implements
 * <i>AES/CFB/PKCS5Padding</i>, and yet another one that implements
 * <i>AES/OFB/PKCS5Padding</i>. That provider would have the following
 * <code>Cipher</code> properties in its master class:
 *
 * <ul>
 *
 * <li>
 * <pre>
 *     <code>Cipher.</code><i>AES/ECB/PKCS5Padding</i>
 * </pre>
 *
 * <li>
 * <pre>
 *     <code>Cipher.</code><i>AES/CBC/PKCS5Padding</i>
 * </pre>
 *
 * <li>
 * <pre>
 *     <code>Cipher.</code><i>AES/CFB/PKCS5Padding</i>
 * </pre>
 *
 * <li>
 * <pre>
 *     <code>Cipher.</code><i>AES/OFB/PKCS5Padding</i>
 * </pre>
 *
 * </ul>
 *
 * <p>Another provider may implement a class for each of the above modes
 * (i.e., one class for <i>ECB</i>, one for <i>CBC</i>, one for <i>CFB</i>,
 * and one for <i>OFB</i>), one class for <i>PKCS5Padding</i>,
 * and a generic <i>AES</i> class that subclasses from <code>CipherSpi</code>.
 * That provider would have the following
 * <code>Cipher</code> properties in its master class:
 *
 * <ul>
 *
 * <li>
 * <pre>
 *     <code>Cipher.</code><i>AES</i>
 * </pre>
 *
 * </ul>
 *
 * <p>The <code>getInstance</code> factory method of the <code>Cipher</code>
 * engine class follows these rules in order to instantiate a provider's
 * implementation of <code>CipherSpi</code> for a
 * transformation of the form "<i>algorithm</i>":
 *
 * <ol>
 * <li>
 * Check if the provider has registered a subclass of <code>CipherSpi</code>
 * for the specified "<i>algorithm</i>".
 * <p>If the answer is YES, instantiate this
 * class, for whose mode and padding scheme default values (as supplied by
 * the provider) are used.
 * <p>If the answer is NO, throw a <code>NoSuchAlgorithmException</code>
 * exception.
 * </ol>
 *
 * <p>The <code>getInstance</code> factory method of the <code>Cipher</code>
 * engine class follows these rules in order to instantiate a provider's
 * implementation of <code>CipherSpi</code> for a
 * transformation of the form "<i>algorithm/mode/padding</i>":
 *
 * <ol>
 * <li>
 * Check if the provider has registered a subclass of <code>CipherSpi</code>
 * for the specified "<i>algorithm/mode/padding</i>" transformation.
 * <p>If the answer is YES, instantiate it.
 * <p>If the answer is NO, go to the next step.
 * <li>
 * Check if the provider has registered a subclass of <code>CipherSpi</code>
 * for the sub-transformation "<i>algorithm/mode</i>".
 * <p>If the answer is YES, instantiate it, and call
 * <code>engineSetPadding(<i>padding</i>)</code> on the new instance.
 * <p>If the answer is NO, go to the next step.
 * <li>
 * Check if the provider has registered a subclass of <code>CipherSpi</code>
 * for the sub-transformation "<i>algorithm//padding</i>" (note the double
 * slashes).
 * <p>If the answer is YES, instantiate it, and call
 * <code>engineSetMode(<i>mode</i>)</code> on the new instance.
 * <p>If the answer is NO, go to the next step.
 * <li>
 * Check if the provider has registered a subclass of <code>CipherSpi</code>
 * for the sub-transformation "<i>algorithm</i>".
 * <p>If the answer is YES, instantiate it, and call
 * <code>engineSetMode(<i>mode</i>)</code> and
 * <code>engineSetPadding(<i>padding</i>)</code> on the new instance.
 * <p>If the answer is NO, throw a <code>NoSuchAlgorithmException</code>
 * exception.
 * </ol>
 *
 * @author Jan Luehe
 * @see KeyGenerator
 * @see SecretKey
 * @since 1.4
 */

public abstract class CipherSpi {

    
Sets the mode of this cipher.
Params:
mode – the cipher mode
Throws:
NoSuchAlgorithmException – if the requested cipher mode does
not exist/**
     * Sets the mode of this cipher.
     *
     * @param mode the cipher mode
     *
     * @exception NoSuchAlgorithmException if the requested cipher mode does
     * not exist
     */
    protected abstract void engineSetMode(String mode)
        throws NoSuchAlgorithmException;

    
Sets the padding mechanism of this cipher.
Params:
padding – the padding mechanism
Throws:
NoSuchPaddingException – if the requested padding mechanism
does not exist/**
     * Sets the padding mechanism of this cipher.
     *
     * @param padding the padding mechanism
     *
     * @exception NoSuchPaddingException if the requested padding mechanism
     * does not exist
     */
    protected abstract void engineSetPadding(String padding)
        throws NoSuchPaddingException;

    
Returns the block size (in bytes).
Returns:
the block size (in bytes), or 0 if the underlying algorithm is
not a block cipher/**
     * Returns the block size (in bytes).
     *
     * @return the block size (in bytes), or 0 if the underlying algorithm is
     * not a block cipher
     */
    protected abstract int engineGetBlockSize();

    
Returns the length in bytes that an output buffer would
need to be in order to hold the result of the next update
or doFinal operation, given the input length
inputLen (in bytes).
This call takes into account any unprocessed (buffered) data from a
previous update call, padding, and AEAD tagging.
The actual output length of the next update or
doFinal call may be smaller than the length returned by
this method.
Params:
inputLen – the input length (in bytes)
Returns:
the required output buffer size (in bytes)/**
     * Returns the length in bytes that an output buffer would
     * need to be in order to hold the result of the next <code>update</code>
     * or <code>doFinal</code> operation, given the input length
     * <code>inputLen</code> (in bytes).
     *
     * <p>This call takes into account any unprocessed (buffered) data from a
     * previous <code>update</code> call, padding, and AEAD tagging.
     *
     * <p>The actual output length of the next <code>update</code> or
     * <code>doFinal</code> call may be smaller than the length returned by
     * this method.
     *
     * @param inputLen the input length (in bytes)
     *
     * @return the required output buffer size (in bytes)
     */
    protected abstract int engineGetOutputSize(int inputLen);

    
Returns the initialization vector (IV) in a new buffer.
 This is useful in the context of password-based encryption or
decryption, where the IV is derived from a user-provided passphrase.
Returns:
the initialization vector in a new buffer, or null if the
underlying algorithm does not use an IV, or if the IV has not yet
been set./**
     * Returns the initialization vector (IV) in a new buffer.
     *
     * <p> This is useful in the context of password-based encryption or
     * decryption, where the IV is derived from a user-provided passphrase.
     *
     * @return the initialization vector in a new buffer, or null if the
     * underlying algorithm does not use an IV, or if the IV has not yet
     * been set.
     */
    protected abstract byte[] engineGetIV();

    
Returns the parameters used with this cipher.
The returned parameters may be the same that were used to initialize
this cipher, or may contain a combination of default and random
parameter values used by the underlying cipher implementation if this
cipher requires algorithm parameters but was not initialized with any.
Returns:
the parameters used with this cipher, or null if this cipher
does not use any parameters./**
     * Returns the parameters used with this cipher.
     *
     * <p>The returned parameters may be the same that were used to initialize
     * this cipher, or may contain a combination of default and random
     * parameter values used by the underlying cipher implementation if this
     * cipher requires algorithm parameters but was not initialized with any.
     *
     * @return the parameters used with this cipher, or null if this cipher
     * does not use any parameters.
     */
    protected abstract AlgorithmParameters engineGetParameters();

    
Initializes this cipher with a key and a source
of randomness.
The cipher is initialized for one of the following four operations:
encryption, decryption, key wrapping or key unwrapping, depending on
the value of opmode.
If this cipher requires any algorithm parameters that cannot be
derived from the given key, the underlying cipher
implementation is supposed to generate the required parameters itself
(using provider-specific default or random values) if it is being
initialized for encryption or key wrapping, and raise an
InvalidKeyException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV). 
If this cipher requires algorithm parameters that cannot be
derived from the input parameters, and there are no reasonable
provider-specific default values, initialization will
necessarily fail.
If this cipher (including its underlying feedback or padding scheme)
requires any random bytes (e.g., for parameter generation), it will get
them from random.
Note that when a Cipher object is initialized, it loses all
previously-acquired state. In other words, initializing a Cipher is
equivalent to creating a new instance of that Cipher and initializing
it.
Params:
opmode – the operation mode of this cipher (this is one of
the following:
ENCRYPT_MODE, DECRYPT_MODE,
WRAP_MODE or UNWRAP_MODE)
key – the encryption key
random – the source of randomness
Throws:
InvalidKeyException – if the given key is inappropriate for
initializing this cipher, or requires
algorithm parameters that cannot be
determined from the given key./**
     * Initializes this cipher with a key and a source
     * of randomness.
     *
     * <p>The cipher is initialized for one of the following four operations:
     * encryption, decryption, key wrapping or key unwrapping, depending on
     * the value of <code>opmode</code>.
     *
     * <p>If this cipher requires any algorithm parameters that cannot be
     * derived from the given <code>key</code>, the underlying cipher
     * implementation is supposed to generate the required parameters itself
     * (using provider-specific default or random values) if it is being
     * initialized for encryption or key wrapping, and raise an
     * <code>InvalidKeyException</code> if it is being
     * initialized for decryption or key unwrapping.
     * The generated parameters can be retrieved using
     * {@link #engineGetParameters() engineGetParameters} or
     * {@link #engineGetIV() engineGetIV} (if the parameter is an IV).
     *
     * <p>If this cipher requires algorithm parameters that cannot be
     * derived from the input parameters, and there are no reasonable
     * provider-specific default values, initialization will
     * necessarily fail.
     *
     * <p>If this cipher (including its underlying feedback or padding scheme)
     * requires any random bytes (e.g., for parameter generation), it will get
     * them from <code>random</code>.
     *
     * <p>Note that when a Cipher object is initialized, it loses all
     * previously-acquired state. In other words, initializing a Cipher is
     * equivalent to creating a new instance of that Cipher and initializing
     * it.
     *
     * @param opmode the operation mode of this cipher (this is one of
     * the following:
     * <code>ENCRYPT_MODE</code>, <code>DECRYPT_MODE</code>,
     * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>)
     * @param key the encryption key
     * @param random the source of randomness
     *
     * @exception InvalidKeyException if the given key is inappropriate for
     * initializing this cipher, or requires
     * algorithm parameters that cannot be
     * determined from the given key.
     */
    protected abstract void engineInit(int opmode, Key key,
                                       SecureRandom random)
        throws InvalidKeyException;

    
Initializes this cipher with a key, a set of
algorithm parameters, and a source of randomness.
The cipher is initialized for one of the following four operations:
encryption, decryption, key wrapping or key unwrapping, depending on
the value of opmode.
If this cipher requires any algorithm parameters and
params is null, the underlying cipher implementation is
supposed to generate the required parameters itself (using
provider-specific default or random values) if it is being
initialized for encryption or key wrapping, and raise an
InvalidAlgorithmParameterException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV). 
If this cipher requires algorithm parameters that cannot be
derived from the input parameters, and there are no reasonable
provider-specific default values, initialization will
necessarily fail.
If this cipher (including its underlying feedback or padding scheme)
requires any random bytes (e.g., for parameter generation), it will get
them from random.
Note that when a Cipher object is initialized, it loses all
previously-acquired state. In other words, initializing a Cipher is
equivalent to creating a new instance of that Cipher and initializing
it.
Params:
opmode – the operation mode of this cipher (this is one of
the following:
ENCRYPT_MODE, DECRYPT_MODE,
WRAP_MODE or UNWRAP_MODE)
key – the encryption key
params – the algorithm parameters
random – the source of randomness
Throws:
InvalidKeyException – if the given key is inappropriate for
initializing this cipher
InvalidAlgorithmParameterException – if the given algorithm
parameters are inappropriate for this cipher,
or if this cipher requires
algorithm parameters and params is null./**
     * Initializes this cipher with a key, a set of
     * algorithm parameters, and a source of randomness.
     *
     * <p>The cipher is initialized for one of the following four operations:
     * encryption, decryption, key wrapping or key unwrapping, depending on
     * the value of <code>opmode</code>.
     *
     * <p>If this cipher requires any algorithm parameters and
     * <code>params</code> is null, the underlying cipher implementation is
     * supposed to generate the required parameters itself (using
     * provider-specific default or random values) if it is being
     * initialized for encryption or key wrapping, and raise an
     * <code>InvalidAlgorithmParameterException</code> if it is being
     * initialized for decryption or key unwrapping.
     * The generated parameters can be retrieved using
     * {@link #engineGetParameters() engineGetParameters} or
     * {@link #engineGetIV() engineGetIV} (if the parameter is an IV).
     *
     * <p>If this cipher requires algorithm parameters that cannot be
     * derived from the input parameters, and there are no reasonable
     * provider-specific default values, initialization will
     * necessarily fail.
     *
     * <p>If this cipher (including its underlying feedback or padding scheme)
     * requires any random bytes (e.g., for parameter generation), it will get
     * them from <code>random</code>.
     *
     * <p>Note that when a Cipher object is initialized, it loses all
     * previously-acquired state. In other words, initializing a Cipher is
     * equivalent to creating a new instance of that Cipher and initializing
     * it.
     *
     * @param opmode the operation mode of this cipher (this is one of
     * the following:
     * <code>ENCRYPT_MODE</code>, <code>DECRYPT_MODE</code>,
     * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>)
     * @param key the encryption key
     * @param params the algorithm parameters
     * @param random the source of randomness
     *
     * @exception InvalidKeyException if the given key is inappropriate for
     * initializing this cipher
     * @exception InvalidAlgorithmParameterException if the given algorithm
     * parameters are inappropriate for this cipher,
     * or if this cipher requires
     * algorithm parameters and <code>params</code> is null.
     */
    protected abstract void engineInit(int opmode, Key key,
                                       AlgorithmParameterSpec params,
                                       SecureRandom random)
        throws InvalidKeyException, InvalidAlgorithmParameterException;

    
Initializes this cipher with a key, a set of
algorithm parameters, and a source of randomness.
The cipher is initialized for one of the following four operations:
encryption, decryption, key wrapping or key unwrapping, depending on
the value of opmode.
If this cipher requires any algorithm parameters and
params is null, the underlying cipher implementation is
supposed to generate the required parameters itself (using
provider-specific default or random values) if it is being
initialized for encryption or key wrapping, and raise an
InvalidAlgorithmParameterException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV). 
If this cipher requires algorithm parameters that cannot be
derived from the input parameters, and there are no reasonable
provider-specific default values, initialization will
necessarily fail.
If this cipher (including its underlying feedback or padding scheme)
requires any random bytes (e.g., for parameter generation), it will get
them from random.
Note that when a Cipher object is initialized, it loses all
previously-acquired state. In other words, initializing a Cipher is
equivalent to creating a new instance of that Cipher and initializing
it.
Params:
opmode – the operation mode of this cipher (this is one of
the following:
ENCRYPT_MODE, DECRYPT_MODE,
WRAP_MODE or UNWRAP_MODE)
key – the encryption key
params – the algorithm parameters
random – the source of randomness
Throws:
InvalidKeyException – if the given key is inappropriate for
initializing this cipher
InvalidAlgorithmParameterException – if the given algorithm
parameters are inappropriate for this cipher,
or if this cipher requires
algorithm parameters and params is null./**
     * Initializes this cipher with a key, a set of
     * algorithm parameters, and a source of randomness.
     *
     * <p>The cipher is initialized for one of the following four operations:
     * encryption, decryption, key wrapping or key unwrapping, depending on
     * the value of <code>opmode</code>.
     *
     * <p>If this cipher requires any algorithm parameters and
     * <code>params</code> is null, the underlying cipher implementation is
     * supposed to generate the required parameters itself (using
     * provider-specific default or random values) if it is being
     * initialized for encryption or key wrapping, and raise an
     * <code>InvalidAlgorithmParameterException</code> if it is being
     * initialized for decryption or key unwrapping.
     * The generated parameters can be retrieved using
     * {@link #engineGetParameters() engineGetParameters} or
     * {@link #engineGetIV() engineGetIV} (if the parameter is an IV).
     *
     * <p>If this cipher requires algorithm parameters that cannot be
     * derived from the input parameters, and there are no reasonable
     * provider-specific default values, initialization will
     * necessarily fail.
     *
     * <p>If this cipher (including its underlying feedback or padding scheme)
     * requires any random bytes (e.g., for parameter generation), it will get
     * them from <code>random</code>.
     *
     * <p>Note that when a Cipher object is initialized, it loses all
     * previously-acquired state. In other words, initializing a Cipher is
     * equivalent to creating a new instance of that Cipher and initializing
     * it.
     *
     * @param opmode the operation mode of this cipher (this is one of
     * the following:
     * <code>ENCRYPT_MODE</code>, <code>DECRYPT_MODE</code>,
     * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>)
     * @param key the encryption key
     * @param params the algorithm parameters
     * @param random the source of randomness
     *
     * @exception InvalidKeyException if the given key is inappropriate for
     * initializing this cipher
     * @exception InvalidAlgorithmParameterException if the given algorithm
     * parameters are inappropriate for this cipher,
     * or if this cipher requires
     * algorithm parameters and <code>params</code> is null.
     */
    protected abstract void engineInit(int opmode, Key key,
                                       AlgorithmParameters params,
                                       SecureRandom random)
        throws InvalidKeyException, InvalidAlgorithmParameterException;

    
Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialized), processing another data
part.
The first inputLen bytes in the input
buffer, starting at inputOffset inclusive, are processed,
and the result is stored in a new buffer.
Params:
input – the input buffer
inputOffset – the offset in input where the input
starts
inputLen – the input length
Returns:
the new buffer with the result, or null if the underlying
cipher is a block cipher and the input data is too short to result in a
new block./**
     * Continues a multiple-part encryption or decryption operation
     * (depending on how this cipher was initialized), processing another data
     * part.
     *
     * <p>The first <code>inputLen</code> bytes in the <code>input</code>
     * buffer, starting at <code>inputOffset</code> inclusive, are processed,
     * and the result is stored in a new buffer.
     *
     * @param input the input buffer
     * @param inputOffset the offset in <code>input</code> where the input
     * starts
     * @param inputLen the input length
     *
     * @return the new buffer with the result, or null if the underlying
     * cipher is a block cipher and the input data is too short to result in a
     * new block.
     */
    protected abstract byte[] engineUpdate(byte[] input, int inputOffset,
                                           int inputLen);

    
Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialized), processing another data
part.
The first inputLen bytes in the input
buffer, starting at inputOffset inclusive, are processed,
and the result is stored in the output buffer, starting at
outputOffset inclusive.
If the output buffer is too small to hold the result,
a ShortBufferException is thrown.
Params:
input – the input buffer
inputOffset – the offset in input where the input
starts
inputLen – the input length
output – the buffer for the result
outputOffset – the offset in output where the result
is stored
Throws:
ShortBufferException – if the given output buffer is too small
to hold the result
Returns:
the number of bytes stored in output/**
     * Continues a multiple-part encryption or decryption operation
     * (depending on how this cipher was initialized), processing another data
     * part.
     *
     * <p>The first <code>inputLen</code> bytes in the <code>input</code>
     * buffer, starting at <code>inputOffset</code> inclusive, are processed,
     * and the result is stored in the <code>output</code> buffer, starting at
     * <code>outputOffset</code> inclusive.
     *
     * <p>If the <code>output</code> buffer is too small to hold the result,
     * a <code>ShortBufferException</code> is thrown.
     *
     * @param input the input buffer
     * @param inputOffset the offset in <code>input</code> where the input
     * starts
     * @param inputLen the input length
     * @param output the buffer for the result
     * @param outputOffset the offset in <code>output</code> where the result
     * is stored
     *
     * @return the number of bytes stored in <code>output</code>
     *
     * @exception ShortBufferException if the given output buffer is too small
     * to hold the result
     */
    protected abstract int engineUpdate(byte[] input, int inputOffset,
                                        int inputLen, byte[] output,
                                        int outputOffset)
        throws ShortBufferException;

    
Continues a multiple-part encryption or decryption operation
(depending on how this cipher was initialized), processing another data
part.
All input.remaining() bytes starting at
input.position() are processed. The result is stored
in the output buffer.
Upon return, the input buffer's position will be equal
to its limit; its limit will not have changed. The output buffer's
position will have advanced by n, where n is the value returned
by this method; the output buffer's limit will not have changed.
If output.remaining() bytes are insufficient to
hold the result, a ShortBufferException is thrown.
Subclasses should consider overriding this method if they can
process ByteBuffers more efficiently than byte arrays.
Params:
input – the input ByteBuffer
output – the output ByteByffer
Throws:
ShortBufferException – if there is insufficient space in the
output buffer
NullPointerException – if either parameter is null
Returns:
the number of bytes stored in output
Since:
1.5/**
     * Continues a multiple-part encryption or decryption operation
     * (depending on how this cipher was initialized), processing another data
     * part.
     *
     * <p>All <code>input.remaining()</code> bytes starting at
     * <code>input.position()</code> are processed. The result is stored
     * in the output buffer.
     * Upon return, the input buffer's position will be equal
     * to its limit; its limit will not have changed. The output buffer's
     * position will have advanced by n, where n is the value returned
     * by this method; the output buffer's limit will not have changed.
     *
     * <p>If <code>output.remaining()</code> bytes are insufficient to
     * hold the result, a <code>ShortBufferException</code> is thrown.
     *
     * <p>Subclasses should consider overriding this method if they can
     * process ByteBuffers more efficiently than byte arrays.
     *
     * @param input the input ByteBuffer
     * @param output the output ByteByffer
     *
     * @return the number of bytes stored in <code>output</code>
     *
     * @exception ShortBufferException if there is insufficient space in the
     * output buffer
     *
     * @throws NullPointerException if either parameter is <CODE>null</CODE>
     * @since 1.5
     */
    protected int engineUpdate(ByteBuffer input, ByteBuffer output)
            throws ShortBufferException {
        try {
            return bufferCrypt(input, output, true);
        } catch (IllegalBlockSizeException e) {
            // never thrown for engineUpdate()
            throw new ProviderException("Internal error in update()");
        } catch (BadPaddingException e) {
            // never thrown for engineUpdate()
            throw new ProviderException("Internal error in update()");
        }
    }

    
Encrypts or decrypts data in a single-part operation,
or finishes a multiple-part operation.
The data is encrypted or decrypted, depending on how this cipher was
initialized.
The first inputLen bytes in the input
buffer, starting at inputOffset inclusive, and any input
bytes that may have been buffered during a previous update
operation, are processed, with padding (if requested) being applied.
If an AEAD mode such as GCM/CCM is being used, the authentication
tag is appended in the case of encryption, or verified in the
case of decryption.
The result is stored in a new buffer.
Upon finishing, this method resets this cipher object to the state
it was in when previously initialized via a call to
engineInit.
That is, the object is reset and available to encrypt or decrypt
(depending on the operation mode that was specified in the call to
engineInit) more data.
Note: if any exception is thrown, this cipher object may need to
be reset before it can be used again.
Params:
input – the input buffer
inputOffset – the offset in input where the input
starts
inputLen – the input length
Throws:
IllegalBlockSizeException – if this cipher is a block cipher,
no padding has been requested (only in encryption mode), and the total
input length of the data processed by this cipher is not a multiple of
block size; or if this encryption algorithm is unable to
process the input data provided.
BadPaddingException – if this cipher is in decryption mode,
and (un)padding has been requested, but the decrypted data is not
bounded by the appropriate padding bytes
AEADBadTagException – if this cipher is decrypting in an
AEAD mode (such as GCM/CCM), and the received authentication tag
does not match the calculated value
Returns:
the new buffer with the result/**
     * Encrypts or decrypts data in a single-part operation,
     * or finishes a multiple-part operation.
     * The data is encrypted or decrypted, depending on how this cipher was
     * initialized.
     *
     * <p>The first <code>inputLen</code> bytes in the <code>input</code>
     * buffer, starting at <code>inputOffset</code> inclusive, and any input
     * bytes that may have been buffered during a previous <code>update</code>
     * operation, are processed, with padding (if requested) being applied.
     * If an AEAD mode such as GCM/CCM is being used, the authentication
     * tag is appended in the case of encryption, or verified in the
     * case of decryption.
     * The result is stored in a new buffer.
     *
     * <p>Upon finishing, this method resets this cipher object to the state
     * it was in when previously initialized via a call to
     * <code>engineInit</code>.
     * That is, the object is reset and available to encrypt or decrypt
     * (depending on the operation mode that was specified in the call to
     * <code>engineInit</code>) more data.
     *
     * <p>Note: if any exception is thrown, this cipher object may need to
     * be reset before it can be used again.
     *
     * @param input the input buffer
     * @param inputOffset the offset in <code>input</code> where the input
     * starts
     * @param inputLen the input length
     *
     * @return the new buffer with the result
     *
     * @exception IllegalBlockSizeException if this cipher is a block cipher,
     * no padding has been requested (only in encryption mode), and the total
     * input length of the data processed by this cipher is not a multiple of
     * block size; or if this encryption algorithm is unable to
     * process the input data provided.
     * @exception BadPaddingException if this cipher is in decryption mode,
     * and (un)padding has been requested, but the decrypted data is not
     * bounded by the appropriate padding bytes
     * @exception AEADBadTagException if this cipher is decrypting in an
     * AEAD mode (such as GCM/CCM), and the received authentication tag
     * does not match the calculated value
     */
    protected abstract byte[] engineDoFinal(byte[] input, int inputOffset,
                                            int inputLen)
        throws IllegalBlockSizeException, BadPaddingException;

    
Encrypts or decrypts data in a single-part operation,
or finishes a multiple-part operation.
The data is encrypted or decrypted, depending on how this cipher was
initialized.
The first inputLen bytes in the input
buffer, starting at inputOffset inclusive, and any input
bytes that may have been buffered during a previous update
operation, are processed, with padding (if requested) being applied.
If an AEAD mode such as GCM/CCM is being used, the authentication
tag is appended in the case of encryption, or verified in the
case of decryption.
The result is stored in the output buffer, starting at
outputOffset inclusive.
If the output buffer is too small to hold the result,
a ShortBufferException is thrown.
Upon finishing, this method resets this cipher object to the state
it was in when previously initialized via a call to
engineInit.
That is, the object is reset and available to encrypt or decrypt
(depending on the operation mode that was specified in the call to
engineInit) more data.
Note: if any exception is thrown, this cipher object may need to
be reset before it can be used again.
Params:
input – the input buffer
inputOffset – the offset in input where the input
starts
inputLen – the input length
output – the buffer for the result
outputOffset – the offset in output where the result
is stored
Throws:
IllegalBlockSizeException – if this cipher is a block cipher,
no padding has been requested (only in encryption mode), and the total
input length of the data processed by this cipher is not a multiple of
block size; or if this encryption algorithm is unable to
process the input data provided.
ShortBufferException – if the given output buffer is too small
to hold the result
BadPaddingException – if this cipher is in decryption mode,
and (un)padding has been requested, but the decrypted data is not
bounded by the appropriate padding bytes
AEADBadTagException – if this cipher is decrypting in an
AEAD mode (such as GCM/CCM), and the received authentication tag
does not match the calculated value
Returns:
the number of bytes stored in output/**
     * Encrypts or decrypts data in a single-part operation,
     * or finishes a multiple-part operation.
     * The data is encrypted or decrypted, depending on how this cipher was
     * initialized.
     *
     * <p>The first <code>inputLen</code> bytes in the <code>input</code>
     * buffer, starting at <code>inputOffset</code> inclusive, and any input
     * bytes that may have been buffered during a previous <code>update</code>
     * operation, are processed, with padding (if requested) being applied.
     * If an AEAD mode such as GCM/CCM is being used, the authentication
     * tag is appended in the case of encryption, or verified in the
     * case of decryption.
     * The result is stored in the <code>output</code> buffer, starting at
     * <code>outputOffset</code> inclusive.
     *
     * <p>If the <code>output</code> buffer is too small to hold the result,
     * a <code>ShortBufferException</code> is thrown.
     *
     * <p>Upon finishing, this method resets this cipher object to the state
     * it was in when previously initialized via a call to
     * <code>engineInit</code>.
     * That is, the object is reset and available to encrypt or decrypt
     * (depending on the operation mode that was specified in the call to
     * <code>engineInit</code>) more data.
     *
     * <p>Note: if any exception is thrown, this cipher object may need to
     * be reset before it can be used again.
     *
     * @param input the input buffer
     * @param inputOffset the offset in <code>input</code> where the input
     * starts
     * @param inputLen the input length
     * @param output the buffer for the result
     * @param outputOffset the offset in <code>output</code> where the result
     * is stored
     *
     * @return the number of bytes stored in <code>output</code>
     *
     * @exception IllegalBlockSizeException if this cipher is a block cipher,
     * no padding has been requested (only in encryption mode), and the total
     * input length of the data processed by this cipher is not a multiple of
     * block size; or if this encryption algorithm is unable to
     * process the input data provided.
     * @exception ShortBufferException if the given output buffer is too small
     * to hold the result
     * @exception BadPaddingException if this cipher is in decryption mode,
     * and (un)padding has been requested, but the decrypted data is not
     * bounded by the appropriate padding bytes
     * @exception AEADBadTagException if this cipher is decrypting in an
     * AEAD mode (such as GCM/CCM), and the received authentication tag
     * does not match the calculated value
     */
    protected abstract int engineDoFinal(byte[] input, int inputOffset,
                                         int inputLen, byte[] output,
                                         int outputOffset)
        throws ShortBufferException, IllegalBlockSizeException,
               BadPaddingException;

    
Encrypts or decrypts data in a single-part operation,
or finishes a multiple-part operation.
The data is encrypted or decrypted, depending on how this cipher was
initialized.
All input.remaining() bytes starting at
input.position() are processed.
If an AEAD mode such as GCM/CCM is being used, the authentication
tag is appended in the case of encryption, or verified in the
case of decryption.
The result is stored in the output buffer.
Upon return, the input buffer's position will be equal
to its limit; its limit will not have changed. The output buffer's
position will have advanced by n, where n is the value returned
by this method; the output buffer's limit will not have changed.
If output.remaining() bytes are insufficient to
hold the result, a ShortBufferException is thrown.
Upon finishing, this method resets this cipher object to the state
it was in when previously initialized via a call to
engineInit.
That is, the object is reset and available to encrypt or decrypt
(depending on the operation mode that was specified in the call to
engineInit) more data.
Note: if any exception is thrown, this cipher object may need to
be reset before it can be used again.
Subclasses should consider overriding this method if they can
process ByteBuffers more efficiently than byte arrays.
Params:
input – the input ByteBuffer
output – the output ByteByffer
Throws:
IllegalBlockSizeException – if this cipher is a block cipher,
no padding has been requested (only in encryption mode), and the total
input length of the data processed by this cipher is not a multiple of
block size; or if this encryption algorithm is unable to
process the input data provided.
ShortBufferException – if there is insufficient space in the
output buffer
BadPaddingException – if this cipher is in decryption mode,
and (un)padding has been requested, but the decrypted data is not
bounded by the appropriate padding bytes
AEADBadTagException – if this cipher is decrypting in an
AEAD mode (such as GCM/CCM), and the received authentication tag
does not match the calculated value
NullPointerException – if either parameter is null
Returns:
the number of bytes stored in output
Since:
1.5/**
     * Encrypts or decrypts data in a single-part operation,
     * or finishes a multiple-part operation.
     * The data is encrypted or decrypted, depending on how this cipher was
     * initialized.
     *
     * <p>All <code>input.remaining()</code> bytes starting at
     * <code>input.position()</code> are processed.
     * If an AEAD mode such as GCM/CCM is being used, the authentication
     * tag is appended in the case of encryption, or verified in the
     * case of decryption.
     * The result is stored in the output buffer.
     * Upon return, the input buffer's position will be equal
     * to its limit; its limit will not have changed. The output buffer's
     * position will have advanced by n, where n is the value returned
     * by this method; the output buffer's limit will not have changed.
     *
     * <p>If <code>output.remaining()</code> bytes are insufficient to
     * hold the result, a <code>ShortBufferException</code> is thrown.
     *
     * <p>Upon finishing, this method resets this cipher object to the state
     * it was in when previously initialized via a call to
     * <code>engineInit</code>.
     * That is, the object is reset and available to encrypt or decrypt
     * (depending on the operation mode that was specified in the call to
     * <code>engineInit</code>) more data.
     *
     * <p>Note: if any exception is thrown, this cipher object may need to
     * be reset before it can be used again.
     *
     * <p>Subclasses should consider overriding this method if they can
     * process ByteBuffers more efficiently than byte arrays.
     *
     * @param input the input ByteBuffer
     * @param output the output ByteByffer
     *
     * @return the number of bytes stored in <code>output</code>
     *
     * @exception IllegalBlockSizeException if this cipher is a block cipher,
     * no padding has been requested (only in encryption mode), and the total
     * input length of the data processed by this cipher is not a multiple of
     * block size; or if this encryption algorithm is unable to
     * process the input data provided.
     * @exception ShortBufferException if there is insufficient space in the
     * output buffer
     * @exception BadPaddingException if this cipher is in decryption mode,
     * and (un)padding has been requested, but the decrypted data is not
     * bounded by the appropriate padding bytes
     * @exception AEADBadTagException if this cipher is decrypting in an
     * AEAD mode (such as GCM/CCM), and the received authentication tag
     * does not match the calculated value
     *
     * @throws NullPointerException if either parameter is <CODE>null</CODE>
     * @since 1.5
     */
    protected int engineDoFinal(ByteBuffer input, ByteBuffer output)
            throws ShortBufferException, IllegalBlockSizeException,
            BadPaddingException {
        return bufferCrypt(input, output, false);
    }

    // copied from sun.security.jca.JCAUtil
    // will be changed to reference that method once that code has been
    // integrated and promoted
    static int getTempArraySize(int totalSize) {
        return Math.min(4096, totalSize);
    }

    
Implementation for encryption using ByteBuffers. Used for both
engineUpdate() and engineDoFinal().
/**
     * Implementation for encryption using ByteBuffers. Used for both
     * engineUpdate() and engineDoFinal().
     */
    private int bufferCrypt(ByteBuffer input, ByteBuffer output,
            boolean isUpdate) throws ShortBufferException,
            IllegalBlockSizeException, BadPaddingException {
        if ((input == null) || (output == null)) {
            throw new NullPointerException
                ("Input and output buffers must not be null");
        }
        int inPos = input.position();
        int inLimit = input.limit();
        int inLen = inLimit - inPos;
        if (isUpdate && (inLen == 0)) {
            return 0;
        }
        int outLenNeeded = engineGetOutputSize(inLen);
        if (output.remaining() < outLenNeeded) {
            throw new ShortBufferException("Need at least " + outLenNeeded
                + " bytes of space in output buffer");
        }

        boolean a1 = input.hasArray();
        boolean a2 = output.hasArray();

        if (a1 && a2) {
            byte[] inArray = input.array();
            int inOfs = input.arrayOffset() + inPos;
            byte[] outArray = output.array();
            int outPos = output.position();
            int outOfs = output.arrayOffset() + outPos;
            int n;
            if (isUpdate) {
                n = engineUpdate(inArray, inOfs, inLen, outArray, outOfs);
            } else {
                n = engineDoFinal(inArray, inOfs, inLen, outArray, outOfs);
            }
            input.position(inLimit);
            output.position(outPos + n);
            return n;
        } else if (!a1 && a2) {
            int outPos = output.position();
            byte[] outArray = output.array();
            int outOfs = output.arrayOffset() + outPos;
            byte[] inArray = new byte[getTempArraySize(inLen)];
            int total = 0;
            do {
                int chunk = Math.min(inLen, inArray.length);
                if (chunk > 0) {
                    input.get(inArray, 0, chunk);
                }
                int n;
                if (isUpdate || (inLen != chunk)) {
                    n = engineUpdate(inArray, 0, chunk, outArray, outOfs);
                } else {
                    n = engineDoFinal(inArray, 0, chunk, outArray, outOfs);
                }
                total += n;
                outOfs += n;
                inLen -= chunk;
            } while (inLen > 0);
            output.position(outPos + total);
            return total;
        } else { // output is not backed by an accessible byte[]
            byte[] inArray;
            int inOfs;
            if (a1) {
                inArray = input.array();
                inOfs = input.arrayOffset() + inPos;
            } else {
                inArray = new byte[getTempArraySize(inLen)];
                inOfs = 0;
            }
            byte[] outArray = new byte[getTempArraySize(outLenNeeded)];
            int outSize = outArray.length;
            int total = 0;
            boolean resized = false;
            do {
                int chunk =
                    Math.min(inLen, (outSize == 0? inArray.length : outSize));
                if (!a1 && !resized && chunk > 0) {
                    input.get(inArray, 0, chunk);
                    inOfs = 0;
                }
                try {
                    int n;
                    if (isUpdate || (inLen != chunk)) {
                        n = engineUpdate(inArray, inOfs, chunk, outArray, 0);
                    } else {
                        n = engineDoFinal(inArray, inOfs, chunk, outArray, 0);
                    }
                    resized = false;
                    inOfs += chunk;
                    inLen -= chunk;
                    if (n > 0) {
                        output.put(outArray, 0, n);
                        total += n;
                    }
                } catch (ShortBufferException e) {
                    if (resized) {
                        // we just resized the output buffer, but it still
                        // did not work. Bug in the provider, abort
                        throw (ProviderException)new ProviderException
                            ("Could not determine buffer size").initCause(e);
                    }
                    // output buffer is too small, realloc and try again
                    resized = true;
                    outSize = engineGetOutputSize(chunk);
                    outArray = new byte[outSize];
                }
            } while (inLen > 0);
            if (a1) {
                input.position(inLimit);
            }
            return total;
        }
    }

    
Wrap a key.
This concrete method has been added to this previously-defined
abstract class. (For backwards compatibility, it cannot be abstract.)
It may be overridden by a provider to wrap a key.
Such an override is expected to throw an IllegalBlockSizeException or
InvalidKeyException (under the specified circumstances),
if the given key cannot be wrapped.
If this method is not overridden, it always throws an
UnsupportedOperationException.
Params:
key – the key to be wrapped.
Throws:
IllegalBlockSizeException – if this cipher is a block cipher,
no padding has been requested, and the length of the encoding of the
key to be wrapped is not a multiple of the block size.
InvalidKeyException – if it is impossible or unsafe to
wrap the key with this cipher (e.g., a hardware protected key is
being passed to a software-only cipher).
Returns:
the wrapped key./**
     * Wrap a key.
     *
     * <p>This concrete method has been added to this previously-defined
     * abstract class. (For backwards compatibility, it cannot be abstract.)
     * It may be overridden by a provider to wrap a key.
     * Such an override is expected to throw an IllegalBlockSizeException or
     * InvalidKeyException (under the specified circumstances),
     * if the given key cannot be wrapped.
     * If this method is not overridden, it always throws an
     * UnsupportedOperationException.
     *
     * @param key the key to be wrapped.
     *
     * @return the wrapped key.
     *
     * @exception IllegalBlockSizeException if this cipher is a block cipher,
     * no padding has been requested, and the length of the encoding of the
     * key to be wrapped is not a multiple of the block size.
     *
     * @exception InvalidKeyException if it is impossible or unsafe to
     * wrap the key with this cipher (e.g., a hardware protected key is
     * being passed to a software-only cipher).
     */
    protected byte[] engineWrap(Key key)
        throws IllegalBlockSizeException, InvalidKeyException
    {
        throw new UnsupportedOperationException();
    }

    
Unwrap a previously wrapped key.
This concrete method has been added to this previously-defined
abstract class. (For backwards compatibility, it cannot be abstract.)
It may be overridden by a provider to unwrap a previously wrapped key.
Such an override is expected to throw an InvalidKeyException if
the given wrapped key cannot be unwrapped.
If this method is not overridden, it always throws an
UnsupportedOperationException.
Params:
wrappedKey – the key to be unwrapped.
wrappedKeyAlgorithm – the algorithm associated with the wrapped
key.
wrappedKeyType – the type of the wrapped key. This is one of
SECRET_KEY, PRIVATE_KEY, or
PUBLIC_KEY.
Throws:
NoSuchAlgorithmException – if no installed providers
can create keys of type wrappedKeyType for the
wrappedKeyAlgorithm.
InvalidKeyException – if wrappedKey does not
represent a wrapped key of type wrappedKeyType for
the wrappedKeyAlgorithm.
Returns:
the unwrapped key./**
     * Unwrap a previously wrapped key.
     *
     * <p>This concrete method has been added to this previously-defined
     * abstract class. (For backwards compatibility, it cannot be abstract.)
     * It may be overridden by a provider to unwrap a previously wrapped key.
     * Such an override is expected to throw an InvalidKeyException if
     * the given wrapped key cannot be unwrapped.
     * If this method is not overridden, it always throws an
     * UnsupportedOperationException.
     *
     * @param wrappedKey the key to be unwrapped.
     *
     * @param wrappedKeyAlgorithm the algorithm associated with the wrapped
     * key.
     *
     * @param wrappedKeyType the type of the wrapped key. This is one of
     * <code>SECRET_KEY</code>, <code>PRIVATE_KEY</code>, or
     * <code>PUBLIC_KEY</code>.
     *
     * @return the unwrapped key.
     *
     * @exception NoSuchAlgorithmException if no installed providers
     * can create keys of type <code>wrappedKeyType</code> for the
     * <code>wrappedKeyAlgorithm</code>.
     *
     * @exception InvalidKeyException if <code>wrappedKey</code> does not
     * represent a wrapped key of type <code>wrappedKeyType</code> for
     * the <code>wrappedKeyAlgorithm</code>.
     */
    protected Key engineUnwrap(byte[] wrappedKey,
                               String wrappedKeyAlgorithm,
                               int wrappedKeyType)
        throws InvalidKeyException, NoSuchAlgorithmException
    {
        throw new UnsupportedOperationException();
    }

    
Returns the key size of the given key object in bits.
This concrete method has been added to this previously-defined
abstract class. It throws an UnsupportedOperationException
if it is not overridden by the provider.
Params:
key – the key object.
Throws:
InvalidKeyException – if key is invalid.
Returns:
the key size of the given key object./**
     * Returns the key size of the given key object in bits.
     * <p>This concrete method has been added to this previously-defined
     * abstract class. It throws an <code>UnsupportedOperationException</code>
     * if it is not overridden by the provider.
     *
     * @param key the key object.
     *
     * @return the key size of the given key object.
     *
     * @exception InvalidKeyException if <code>key</code> is invalid.
     */
    protected int engineGetKeySize(Key key)
        throws InvalidKeyException
    {
        throw new UnsupportedOperationException();
    }

    
Continues a multi-part update of the Additional Authentication
Data (AAD), using a subset of the provided buffer.
 Calls to this method provide AAD to the cipher when operating in modes such as AEAD (GCM/CCM). If this cipher is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the update and 
doFinal methods). 
Params:
src – the buffer containing the AAD
offset – the offset in src where the AAD input starts
len – the number of AAD bytes
Throws:
IllegalStateException – if this cipher is in a wrong state (e.g., has not been initialized), does not accept AAD, or if operating in either GCM or CCM mode and one of the update methods has already been called for the active encryption/decryption operation
UnsupportedOperationException – if this method
has not been overridden by an implementation
Since:
1.7/**
     * Continues a multi-part update of the Additional Authentication
     * Data (AAD), using a subset of the provided buffer.
     * <p>
     * Calls to this method provide AAD to the cipher when operating in
     * modes such as AEAD (GCM/CCM).  If this cipher is operating in
     * either GCM or CCM mode, all AAD must be supplied before beginning
     * operations on the ciphertext (via the {@code update} and {@code
     * doFinal} methods).
     *
     * @param src the buffer containing the AAD
     * @param offset the offset in {@code src} where the AAD input starts
     * @param len the number of AAD bytes
     *
     * @throws IllegalStateException if this cipher is in a wrong state
     * (e.g., has not been initialized), does not accept AAD, or if
     * operating in either GCM or CCM mode and one of the {@code update}
     * methods has already been called for the active
     * encryption/decryption operation
     * @throws UnsupportedOperationException if this method
     * has not been overridden by an implementation
     *
     * @since 1.7
     */
    protected void engineUpdateAAD(byte[] src, int offset, int len) {
        throw new UnsupportedOperationException(
            "The underlying Cipher implementation "
            +  "does not support this method");
    }

    
Continues a multi-part update of the Additional Authentication
Data (AAD).
 Calls to this method provide AAD to the cipher when operating in modes such as AEAD (GCM/CCM). If this cipher is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the update and 
doFinal methods). 
 All src.remaining() bytes starting at src.position() are processed. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. 
Params:
src – the buffer containing the AAD
Throws:
IllegalStateException – if this cipher is in a wrong state (e.g., has not been initialized), does not accept AAD, or if operating in either GCM or CCM mode and one of the update methods has already been called for the active encryption/decryption operation
UnsupportedOperationException – if this method
has not been overridden by an implementation
Since:
1.7/**
     * Continues a multi-part update of the Additional Authentication
     * Data (AAD).
     * <p>
     * Calls to this method provide AAD to the cipher when operating in
     * modes such as AEAD (GCM/CCM).  If this cipher is operating in
     * either GCM or CCM mode, all AAD must be supplied before beginning
     * operations on the ciphertext (via the {@code update} and {@code
     * doFinal} methods).
     * <p>
     * All {@code src.remaining()} bytes starting at
     * {@code src.position()} are processed.
     * Upon return, the input buffer's position will be equal
     * to its limit; its limit will not have changed.
     *
     * @param src the buffer containing the AAD
     *
     * @throws IllegalStateException if this cipher is in a wrong state
     * (e.g., has not been initialized), does not accept AAD, or if
     * operating in either GCM or CCM mode and one of the {@code update}
     * methods has already been called for the active
     * encryption/decryption operation
     * @throws UnsupportedOperationException if this method
     * has not been overridden by an implementation
     *
     * @since 1.7
     */
    protected void engineUpdateAAD(ByteBuffer src) {
        throw new UnsupportedOperationException(
            "The underlying Cipher implementation "
            +  "does not support this method");
    }
}