Package org.bouncycastle.crypto.modes

Class CFBBlockCipher

java.lang.Object
org.bouncycastle.crypto.DefaultMultiBlockCipher
org.bouncycastle.crypto.StreamBlockCipher
org.bouncycastle.crypto.modes.CFBBlockCipher
All Implemented Interfaces:
BlockCipher, CFBModeCipher, MultiBlockCipher, StreamCipher
public class CFBBlockCipher extends StreamBlockCipher implements CFBModeCipher
implements a Cipher-FeedBack (CFB) mode on top of a simple cipher.

  • Constructor Details

    • CFBBlockCipher

      public CFBBlockCipher(BlockCipher cipher, int bitBlockSize)
      Deprecated.
      use the equivalent CFBBlockCipher.newInstance() static method.
      Basic constructor.
      Parameters:
      cipher - the block cipher to be used as the basis of the feedback mode.
      bitBlockSize - the block size in bits (note: a multiple of 8)

  • Method Details

    • newInstance

      public static CFBModeCipher newInstance(BlockCipher cipher, int blockSize)
      Return a new CFB mode cipher based on the passed in base cipher
      Parameters:
      cipher - the base cipher for the CFB mode.
      blockSize - the block size (in bits) used for the CFB mode.

    • 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
      Specified by:
      init in interface StreamCipher
      Parameters:
      encrypting - if true the cipher is initialised for encryption, if false for decryption.
      params - 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
      Specified by:
      getAlgorithmName in interface StreamCipher
      Returns:
      the name of the underlying algorithm followed by "/CFB" and the block size in bits.

    • calculateByte

      protected byte calculateByte(byte in) throws DataLengthException, IllegalStateException
      Specified by:
      calculateByte in class StreamBlockCipher
      Throws:
      DataLengthException
      IllegalStateException

    • 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.

    • getCurrentIV

      public byte[] getCurrentIV()
      Return the current state of the initialisation vector.
      Returns:
      current IV

    • reset

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