public class CBC extends FeedbackMode
References:
Copyright © 1997, 1998
Systemics Ltd on behalf of the
Cryptix Development Team.
All rights reserved.
$Revision: 1.7 $
Modifier and Type | Field and Description |
---|---|
protected byte[] |
xorBlock
Temporary buffer to hold input bytes when there's not enough of
them to cipher.
|
currentByte, ivBlock, ivStart, length
DECRYPT, ENCRYPT, UNINITIALIZED
Constructor and Description |
---|
CBC()
Constructs a CBC cipher, assuming that the IV will be provided
via
setInitializationVector . |
CBC(Cipher cipher)
Constructs a CBC cipher, assuming that the IV will be provided
via
setInitializationVector . |
CBC(Cipher cipher,
byte[] iv)
Constructs a CBC cipher, using an initialization vector
provided in the constructor.
|
Modifier and Type | Method and Description |
---|---|
protected int |
engineBlockSize()
SPI: Returns the length of a block, in bytes.
|
protected void |
engineInitDecrypt(java.security.Key newkey)
SPI: Initializes this cipher for decryption, using the
specified key.
|
protected void |
engineInitEncrypt(java.security.Key newkey)
SPI: Initializes this cipher for encryption, using the
specified key.
|
protected void |
engineSetCipher(Cipher cipher)
SPI: Sets the underlying cipher.
|
protected int |
engineUpdate(byte[] in,
int inOffset,
int inLen,
byte[] out,
int outOffset)
SPI: This is the main engine method for updating data.
|
getInitializationVector, getInitializationVectorLength, setInitializationVector
engineGetParameter, engineSetParameter, getAlgorithms, getAlgorithms, getInstance, getInstance, toString
blockSize, clone, crypt, crypt, crypt, doFinal, doFinal, doFinal, doFinal, engineCiphertextBlockSize, engineCrypt, engineInBufferSize, engineOutBufferSize, enginePlaintextBlockSize, engineSetPaddingScheme, getAlgorithm, getCiphertextBlockSize, getInputBlockSize, getInstance, getMode, getOutputBlockSize, getPadding, getPaddingScheme, getParameter, getPlaintextBlockSize, getProvider, getState, inBufferSize, inBufferSizeFinal, initDecrypt, initEncrypt, isPaddingBlockCipher, outBufferSize, outBufferSizeFinal, setParameter, update, update, update, update
protected byte[] xorBlock
public CBC()
setInitializationVector
.
The IV value should be random, but unlike CFB mode, it is not absolutely required to be unique.
public CBC(Cipher cipher)
setInitializationVector
.
See the previous constructor for more details.cipher
- the cipher object to use in CBC mode.java.lang.NullPointerException
- if cipher == nullIllegalBlockSizeException
- if cipher.getPlaintextBlockSize() !=
cipher.getCiphertextBlockSize()public CBC(Cipher cipher, byte[] iv)
For CBC mode the IV value should be random, but unlike CFB mode, it is not absolutely required to be unique.
cipher
- the block cipher to useiv
- the initial value for the shift register (IV)java.lang.NullPointerException
- if cipher == nullprotected void engineSetCipher(Cipher cipher)
FeedbackMode
For example, to create an IDEA cipher in CBC mode, the cipher for "IDEA" would be passed to the mode for "CBC" using this method. It is called once, immediately after the mode object is constructed.
Subclasses that override this method (to do initialization that
depends on the cipher being set) should call
super.engineSetCipher(cipher)
first.
engineSetCipher
in class FeedbackMode
cipher
- the underlying cipher objectprotected int engineBlockSize()
Cipher
The value may change when initEncrypt
or
initDecrypt
is called, but it should not change at
other times.
engineBlockSize
in class Cipher
protected void engineInitEncrypt(java.security.Key newkey) throws java.security.KeyException
Cipher
After a call to this method, the cipher's state is set to ENCRYPT.
engineInitEncrypt
in class Cipher
newkey
- the key to use for encryption.java.security.KeyException
- if the key is invalid.protected void engineInitDecrypt(java.security.Key newkey) throws java.security.KeyException
Cipher
After a call to this method, the cipher's state is set to DECRYPT.
engineInitDecrypt
in class Cipher
newkey
- the key to use for decryption.java.security.KeyException
- if the key is invalid.protected int engineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
in
and out
may be the same array, and the
input and output regions may overlap.
engineUpdate
in class Cipher
in
- the input data.inOffset
- the offset into in
specifying where
the data starts.inLen
- the length of the subarray.out
- the output array.outOffset
- the offset indicating where to start writing into
the out
array.