Class CBCBlockCipher

java.lang.Object
org.gudy.bouncycastle.crypto.modes.CBCBlockCipher
All Implemented Interfaces:
BlockCipher
public class CBCBlockCipher extends Object implements BlockCipher
implements Cipher-Block-Chaining (CBC) mode on top of a simple cipher.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private int
    blockSize
     
    private byte[]
    cbcNextV
     
    private byte[]
    cbcV
     
    private BlockCipher
    cipher
     
    private boolean
    encrypting
     
    private byte[]
    IV
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    CBCBlockCipher(BlockCipher cipher)
    Basic constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    private int
    decryptBlock(byte[] in, int inOff, byte[] out, int outOff)
    Do the appropriate chaining step for CBC mode decryption.
    private int
    encryptBlock(byte[] in, int inOff, byte[] out, int outOff)
    Do the appropriate chaining step for CBC mode encryption.
    String
    getAlgorithmName()
    return the algorithm name and mode.
    int
    getBlockSize()
    return the block size of the underlying cipher.
    BlockCipher
    getUnderlyingCipher()
    return the underlying block cipher that we are wrapping.
    void
    init(boolean encrypting, CipherParameters params)
    Initialise the cipher and, possibly, the initialisation vector (IV).
    int
    processBlock(byte[] in, int inOff, byte[] out, int outOff)
    Process one block of input from the array in and write it to the out array.
    void
    reset()
    reset the chaining vector back to the IV and reset the underlying cipher.

    Methods inherited from class Object

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

  • Field Details

    • IV

      private byte[] IV

    • cbcV

      private byte[] cbcV

    • cbcNextV

      private byte[] cbcNextV

    • blockSize

      private int blockSize

    • cipher

      private BlockCipher cipher

    • encrypting

      private boolean encrypting

  • Constructor Details

    • CBCBlockCipher

      public CBCBlockCipher(BlockCipher cipher)
      Basic constructor.
      Parameters:
      cipher - the block cipher to be used as the basis of chaining.

  • Method Details

    • getUnderlyingCipher

      public BlockCipher getUnderlyingCipher()
      return the underlying block cipher that we are wrapping.
      Returns:
      the underlying block cipher that we are wrapping.

    • init

      public void init(boolean encrypting, CipherParameters params) throws IllegalArgumentException
      Initialise the cipher and, possibly, the initialisation vector (IV). If an IV isn't passed as part of the parameter, the IV will be all zeros.
      Specified by:
      init in interface BlockCipher
      Parameters:
      encrypting - if true the cipher is initialised for encryption, if false for decryption.
      forEncryption - if true the cipher is initialised for encryption, if false for decryption.
      param - the key and other data required by the cipher.
      Throws:
      IllegalArgumentException - if the params argument is inappropriate.

    • getAlgorithmName

      public String getAlgorithmName()
      return the algorithm name and mode.
      Specified by:
      getAlgorithmName in interface BlockCipher
      Returns:
      the name of the underlying algorithm followed by "/CBC".

    • getBlockSize

      public int getBlockSize()
      return the block size of the underlying cipher.
      Specified by:
      getBlockSize in interface BlockCipher
      Returns:
      the block size of the underlying cipher.

    • processBlock

      public int processBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, IllegalStateException
      Process one block of input from the array in and write it to the out array.
      Specified by:
      processBlock in interface BlockCipher
      Parameters:
      in - the array containing the input data.
      inOff - offset into the in array the data starts at.
      out - the array the output data will be copied into.
      outOff - the offset into the out array the output will start at.
      Returns:
      the number of bytes processed and produced.
      Throws:
      DataLengthException - if there isn't enough data in in, or space in out.
      IllegalStateException - if the cipher isn't initialised.

    • reset

      public void reset()
      reset the chaining vector back to the IV and reset the underlying cipher.
      Specified by:
      reset in interface BlockCipher

    • encryptBlock

      private int encryptBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, IllegalStateException
      Do the appropriate chaining step for CBC mode encryption.
      Parameters:
      in - the array containing the data to be encrypted.
      inOff - offset into the in array the data starts at.
      out - the array the encrypted data will be copied into.
      outOff - the offset into the out array the output will start at.
      Returns:
      the number of bytes processed and produced.
      Throws:
      DataLengthException - if there isn't enough data in in, or space in out.
      IllegalStateException - if the cipher isn't initialised.

    • decryptBlock

      private int decryptBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, IllegalStateException
      Do the appropriate chaining step for CBC mode decryption.
      Parameters:
      in - the array containing the data to be decrypted.
      inOff - offset into the in array the data starts at.
      out - the array the decrypted data will be copied into.
      outOff - the offset into the out array the output will start at.
      Returns:
      the number of bytes processed and produced.
      Throws:
      DataLengthException - if there isn't enough data in in, or space in out.
      IllegalStateException - if the cipher isn't initialised.