protected int engineDoFinal(ByteBuffer input,
    ByteBuffer output) throws ShortBufferException, IllegalBlockSizeException, BadPaddingException 
{
        return bufferCrypt(input, output, false);
}

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.

 abstract protected 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 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.

 abstract protected 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.

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.

 abstract protected int engineGetBlockSize()
Returns the block size (in bytes).

 abstract protected byte[] engineGetIV()
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.

 protected int engineGetKeySize(Key key) throws InvalidKeyException 
{
        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.

 abstract protected int engineGetOutputSize(int inputLen)
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.

 abstract protected AlgorithmParameters engineGetParameters()
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.

 abstract protected  void engineInit(int opmode,
    Key key,
    SecureRandom random) throws InvalidKeyException
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.

 abstract protected  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.

 abstract protected  void engineInit(int opmode,
    Key key,
    AlgorithmParameters 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.

 abstract protected  void engineSetMode(String mode) throws NoSuchAlgorithmException
Sets the mode of this cipher.

 abstract protected  void engineSetPadding(String padding) throws NoSuchPaddingException
Sets the padding mechanism of this cipher.

 protected Key engineUnwrap(byte[] wrappedKey,
    String wrappedKeyAlgorithm,
    int wrappedKeyType) throws InvalidKeyException, NoSuchAlgorithmException 
{
        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.

 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()");
        }
}

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.

 abstract protected 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 a new buffer.

 abstract protected 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.

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.

 protected  void engineUpdateAAD(ByteBuffer src) 
{
        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 {@code update} and {@code doFinal} methods).

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.

 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), 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 {@code update} and {@code doFinal} methods).

 protected byte[] engineWrap(Key key) throws IllegalBlockSizeException, InvalidKeyException 
{
        throw new UnsupportedOperationException();
}

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.

 static int getTempArraySize(int totalSize) 
{
        return Math.min(4096, totalSize);
}