Class CFBBlockCipher

java.lang.Object
org.gudy.bouncycastle.crypto.modes.CFBBlockCipher
All Implemented Interfaces:
BlockCipher

public class CFBBlockCipher extends Object implements BlockCipher
implements a Cipher-FeedBack (CFB) mode on top of a simple cipher.
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private int
     
    private byte[]
     
    private byte[]
     
    private BlockCipher
     
    private boolean
     
    private byte[]
     
  • Constructor Summary

    Constructors
    Constructor
    Description
    CFBBlockCipher(BlockCipher cipher, int bitBlockSize)
    Basic constructor.
  • Method Summary

    Modifier and Type
    Method
    Description
    int
    decryptBlock(byte[] in, int inOff, byte[] out, int outOff)
    Do the appropriate processing for CFB mode decryption.
    int
    encryptBlock(byte[] in, int inOff, byte[] out, int outOff)
    Do the appropriate processing for CFB mode encryption.
    return the algorithm name and mode.
    int
    return the block size we are operating at.
    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 the chaining vector back to the IV and reset the underlying cipher.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • IV

      private byte[] IV
    • cfbV

      private byte[] cfbV
    • cfbOutV

      private byte[] cfbOutV
    • blockSize

      private int blockSize
    • cipher

      private BlockCipher cipher
    • encrypting

      private boolean encrypting
  • Constructor Details

    • CFBBlockCipher

      public CFBBlockCipher(BlockCipher cipher, int bitBlockSize)
      Basic constructor.
      Parameters:
      cipher - the block cipher to be used as the basis of the feedback mode.
      blockSize - the block size in bits (note: a multiple of 8)
  • 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. An IV which is too short is handled in FIPS compliant fashion.
      Specified by:
      init in interface BlockCipher
      Parameters:
      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 "/CFB" and the block size in bits.
    • getBlockSize

      public int getBlockSize()
      return the block size we are operating at.
      Specified by:
      getBlockSize in interface BlockCipher
      Returns:
      the block size we are operating at (in bytes).
    • 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.
    • encryptBlock

      public int encryptBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, IllegalStateException
      Do the appropriate processing for CFB 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

      public int decryptBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, IllegalStateException
      Do the appropriate processing for CFB 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 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.
    • reset

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