OCBBlockCipher (Bouncy Castle Library 1.85 API Specification)
Date: 2026-07-12

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

    Constructors
    Constructor and Description
    `OCBBlockCipher(BlockCipher hashCipher, BlockCipher mainCipher)`

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `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)