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## org.bouncycastle.crypto.modes
Class OCBBlockCipher

    java.lang.Object
      org.bouncycastle.crypto.modes.OCBBlockCipher

All Implemented Interfaces:
  AEADBlockCipher, AEADCipher

public class OCBBlockCipher
extends java.lang.Object
implements AEADBlockCipher

An implementation of RFC 7253 on The OCB Authenticated-Encryption Algorithm. For those still concerned about the original patents around this, please see:

https://mailarchive.ietf.org/arch/msg/cfrg/qLTveWOdTJcLn4HP3ev-vrj05Vg/

Text reproduced below. Phillip Rogaway >rogaway@cs.ucdavis.edu< Sat, 27 February 2021 02:46 UTCShow header I can confirm that I have abandoned all OCB patents and placed into the public domain all OCB-related IP of mine. While I have been telling people this for quite some time, I don't think I ever made a proper announcement to the CFRG or on the OCB webpage. Consider that done.

Constructor Summary
`OCBBlockCipher(BlockCipher hashCipher, BlockCipher mainCipher)`

Method Summary
`protected void` | `clear(byte[] bs)`
`int` | `doFinal(byte[] output, int outOff)` Finish the operation either appending or verifying the MAC at the end of the data.
`java.lang.String` | `getAlgorithmName()` Return the name of the algorithm.
`protected byte[]` | `getLSub(int n)`
`byte[]` | `getMac()` Return the value of the MAC associated with the last stream processed.
`int` | `getOutputSize(int len)` return the size of the output buffer required for a processBytes plus a doFinal with an input of len bytes.
`BlockCipher` | `getUnderlyingCipher()` return the `BlockCipher` this object wraps.
`int` | `getUpdateOutputSize(int len)` return the size of the output buffer required for a processBytes an input of len bytes.
`void` | `init(boolean forEncryption, CipherParameters parameters)` initialise the underlying cipher.
`protected static byte[]` | `OCB_double(byte[] block)`
`protected static void` | `OCB_extend(byte[] block, int pos)`
`protected static int` | `OCB_ntz(long x)`
`void` | `processAADByte(byte input)` Add a single byte to the associated data check.
`void` | `processAADBytes(byte[] input, int off, int len)` Add a sequence of bytes to the associated data check.
`int` | `processByte(byte input, byte[] output, int outOff)` encrypt/decrypt a single byte.
`int` | `processBytes(byte[] input, int inOff, int len, byte[] output, int outOff)` process a block of bytes from in putting the result into out.
`protected void` | `processHashBlock()`
`protected void` | `processMainBlock(byte[] output, int outOff)`
`protected int` | `processNonce(byte[] N)`
`void` | `reset()` Reset the cipher.
`protected void` | `reset(boolean clearMac)`
`protected static int` | `shiftLeft(byte[] block, byte[] output)`
`protected void` | `updateHASH(byte[] LSub)`
`protected static void` | `xor(byte[] block, byte[] val)`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### OCBBlockCipher

    public OCBBlockCipher(BlockCipher hashCipher,
                          BlockCipher mainCipher)

Method Detail

### getUnderlyingCipher

    public BlockCipher getUnderlyingCipher()

  Description copied from interface: `AEADBlockCipher`
  return the `BlockCipher` this object wraps.

  Specified by:
    `getUnderlyingCipher` in interface `AEADBlockCipher`
  Returns:
    the `BlockCipher` this object wraps.

### getAlgorithmName

    public java.lang.String getAlgorithmName()

  Description copied from interface: `AEADCipher`
  Return the name of the algorithm.

  Specified by:
    `getAlgorithmName` in interface `AEADCipher`
  Returns:
    the algorithm name.

### init

    public void init(boolean forEncryption,
                     CipherParameters parameters)
              throws java.lang.IllegalArgumentException

  Description copied from interface: `AEADCipher`
  initialise the underlying cipher. Parameter can either be an AEADParameters or a ParametersWithIV object.

  Specified by:
    `init` in interface `AEADCipher`
  Parameters:
    `forEncryption` - true if we are setting up for encryption, false otherwise.
    `parameters` - the necessary parameters for the underlying cipher to be initialised.
  Throws:
    `java.lang.IllegalArgumentException` - if the params argument is inappropriate.

### processNonce

    protected int processNonce(byte[] N)

### getMac

    public byte[] getMac()

  Description copied from interface: `AEADCipher`
  Return the value of the MAC associated with the last stream processed.

  Specified by:
    `getMac` in interface `AEADCipher`
  Returns:
    MAC for plaintext data.

### getOutputSize

    public int getOutputSize(int len)

  Description copied from interface: `AEADCipher`
  return the size of the output buffer required for a processBytes plus a doFinal with an input of len bytes.

  The returned size may be dependent on the initialisation of this cipher and may not be accurate once subsequent input data is processed - this method should be invoked immediately prior to a call to final processing of input data and a call to `AEADCipher.doFinal(byte[], int)`.

  Specified by:
    `getOutputSize` in interface `AEADCipher`
  Parameters:
    `len` - the length of the input.
  Returns:
    the space required to accommodate a call to processBytes and doFinal with len bytes of input.

### getUpdateOutputSize

    public int getUpdateOutputSize(int len)

  Description copied from interface: `AEADCipher`
  return the size of the output buffer required for a processBytes an input of len bytes.

  The returned size may be dependent on the initialisation of this cipher and may not be accurate once subsequent input data is processed - this method should be invoked immediately prior to input data being processed.

  Specified by:
    `getUpdateOutputSize` in interface `AEADCipher`
  Parameters:
    `len` - the length of the input.
  Returns:
    the space required to accommodate a call to processBytes with len bytes of input.

### processAADByte

    public void processAADByte(byte input)

  Description copied from interface: `AEADCipher`
  Add a single byte to the associated data check. If the implementation supports it, this will be an online operation and will not retain the associated data.

  Specified by:
    `processAADByte` in interface `AEADCipher`
  Parameters:
    `input` - the byte to be processed.

### processAADBytes

    public void processAADBytes(byte[] input,
                                int off,
                                int len)

  Description copied from interface: `AEADCipher`
  Add a sequence of bytes to the associated data check. If the implementation supports it, this will be an online operation and will not retain the associated data.

  Specified by:
    `processAADBytes` in interface `AEADCipher`
  Parameters:
    `input` - the input byte array.
    `off` - the offset into the in array where the data to be processed starts.
    `len` - the number of bytes to be processed.

### processByte

    public int processByte(byte input,
                           byte[] output,
                           int outOff)
                    throws DataLengthException

  Description copied from interface: `AEADCipher`
  encrypt/decrypt a single byte.

  Specified by:
    `processByte` in interface `AEADCipher`
  Parameters:
    `input` - the byte to be processed.
    `output` - the output buffer the processed byte goes into.
    `outOff` - the offset into the output byte array the processed data starts at.
  Returns:
    the number of bytes written to out.
  Throws:
    `DataLengthException` - if the output buffer is too small.

### processBytes

    public int processBytes(byte[] input,
                            int inOff,
                            int len,
                            byte[] output,
                            int outOff)
                     throws DataLengthException

  Description copied from interface: `AEADCipher`
  process a block of bytes from in putting the result into out.

  Specified by:
    `processBytes` in interface `AEADCipher`
  Parameters:
    `input` - the input byte array.
    `inOff` - the offset into the in array where the data to be processed starts.
    `len` - the number of bytes to be processed.
    `output` - the output buffer the processed bytes go into.
    `outOff` - the offset into the output byte array the processed data starts at.
  Returns:
    the number of bytes written to out.
  Throws:
    `DataLengthException` - if the output buffer is too small.

### doFinal

    public int doFinal(byte[] output,
                       int outOff)
                throws java.lang.IllegalStateException,
                       InvalidCipherTextException

  Description copied from interface: `AEADCipher`
  Finish the operation either appending or verifying the MAC at the end of the data.

  Specified by:
    `doFinal` in interface `AEADCipher`
  Parameters:
    `output` - space for any resulting output data.
    `outOff` - offset into out to start copying the data at.
  Returns:
    number of bytes written into out.
  Throws:
    `java.lang.IllegalStateException` - if the cipher is in an inappropriate state.
    `InvalidCipherTextException` - if the MAC fails to match.

### reset

    public void reset()

  Description copied from interface: `AEADCipher`
  Reset the cipher. After resetting the cipher is in the same state as it was after the last init (if there was one).

  Specified by:
    `reset` in interface `AEADCipher`

### clear

    protected void clear(byte[] bs)

### getLSub

    protected byte[] getLSub(int n)

### processHashBlock

    protected void processHashBlock()

### processMainBlock

    protected void processMainBlock(byte[] output,
                                    int outOff)

### reset

    protected void reset(boolean clearMac)

### updateHASH

    protected void updateHASH(byte[] LSub)

### OCB_double

    protected static byte[] OCB_double(byte[] block)

### OCB_extend

    protected static void OCB_extend(byte[] block,
                                     int pos)

### OCB_ntz

    protected static int OCB_ntz(long x)

### shiftLeft

    protected static int shiftLeft(byte[] block,
                                   byte[] output)

### xor

    protected static void xor(byte[] block,
                              byte[] val)

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