CFBBlockCipher (Bouncy Castle Library 1.60 API Specification)

java.lang.Object
- org.bouncycastle.crypto.StreamBlockCipher
- - org.bouncycastle.crypto.modes.CFBBlockCipher

All Implemented Interfaces:

BlockCipher, StreamCipher
```
public class CFBBlockCipher
extends StreamBlockCipher
```
implements a Cipher-FeedBack (CFB) mode on top of a simple cipher.

Constructor Summary

Constructors
Constructor Description

CFBBlockCipher(BlockCipher cipher, int bitBlockSize)
Basic constructor.

Constructors
Constructor	Description
`CFBBlockCipher(BlockCipher cipher, int bitBlockSize)`	Basic constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected byte`	`calculateByte(byte in)`
`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.
`java.lang.String`	`getAlgorithmName()`	return the algorithm name and mode.
`int`	`getBlockSize()`	return the block size we are operating at.
`byte[]`	`getCurrentIV()`	Return the current state of the initialisation vector.
`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 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from class org.bouncycastle.crypto.StreamBlockCipher
getUnderlyingCipher, processBytes, returnByte

- Constructor Detail
  - CFBBlockCipher
```
public CFBBlockCipher(BlockCipher cipher,
                      int bitBlockSize)
```
    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 Detail
  - init
```
public void init(boolean encrypting,
                 CipherParameters params)
          throws java.lang.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.
    
    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:
    
    java.lang.IllegalArgumentException - if the params argument is inappropriate.
  - getAlgorithmName
```
public java.lang.String getAlgorithmName()
```
    return the algorithm name and mode.
    
    Returns:
    
    the name of the underlying algorithm followed by "/CFB" and the block size in bits.
  - calculateByte
```
protected byte calculateByte(byte in)
                      throws DataLengthException,
                             java.lang.IllegalStateException
```
    Specified by:
    
    calculateByte in class StreamBlockCipher
    
    Throws:
    
    DataLengthException
    
    java.lang.IllegalStateException
  - getBlockSize
```
public int getBlockSize()
```
    return the block size we are operating at.
    
    Returns:
    
    the block size we are operating at (in bytes).
  - processBlock
```
public int processBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)
                 throws DataLengthException,
                        java.lang.IllegalStateException
```
    Process one block of input from the array in and write it to the out array.
    
    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.
    
    java.lang.IllegalStateException - if the cipher isn't initialised.
  - encryptBlock
```
public int encryptBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)
                 throws DataLengthException,
                        java.lang.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.
    
    java.lang.IllegalStateException - if the cipher isn't initialised.
  - decryptBlock
```
public int decryptBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)
                 throws DataLengthException,
                        java.lang.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.
    
    java.lang.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.

Class CFBBlockCipher

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from class org.bouncycastle.crypto.StreamBlockCipher

Constructor Detail

CFBBlockCipher

Method Detail

init

getAlgorithmName

calculateByte

getBlockSize

processBlock

encryptBlock

decryptBlock

getCurrentIV

reset