Class OpenPGPCFBBlockCipher
java.lang.Object
org.gudy.bouncycastle.crypto.modes.OpenPGPCFBBlockCipher
- All Implemented Interfaces:
BlockCipher
Implements OpenPGP's rather strange version of Cipher-FeedBack (CFB) mode
on top of a simple cipher. This class assumes the IV has been prepended
to the data stream already, and just accommodates the reset after
(blockSize + 2) bytes have been read.
For further info see RFC 2440.
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate int
private BlockCipher
private int
private boolean
private byte[]
private byte[]
private byte[]
private byte[]
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate int
decryptBlock
(byte[] in, int inOff, byte[] out, int outOff) Do the appropriate processing for CFB IV mode decryption.private int
encryptBlock
(byte[] in, int inOff, byte[] out, int outOff) Do the appropriate processing for CFB IV mode encryption.private byte
encryptByte
(byte data, int blockOff) Encrypt one byte of data according to CFB mode.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 forEncryption, 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.
-
Field Details
-
IV
private byte[] IV -
FR
private byte[] FR -
FRE
private byte[] FRE -
tmp
private byte[] tmp -
cipher
-
count
private int count -
blockSize
private int blockSize -
forEncryption
private boolean forEncryption
-
-
Constructor Details
-
OpenPGPCFBBlockCipher
Basic constructor.- Parameters:
cipher
- the block cipher to be used as the basis of the feedback mode.
-
-
Method Details
-
getUnderlyingCipher
return the underlying block cipher that we are wrapping.- Returns:
- the underlying block cipher that we are wrapping.
-
getAlgorithmName
return the algorithm name and mode.- Specified by:
getAlgorithmName
in interfaceBlockCipher
- Returns:
- the name of the underlying algorithm followed by "/PGPCFB" and the block size in bits.
-
getBlockSize
public int getBlockSize()return the block size we are operating at.- Specified by:
getBlockSize
in interfaceBlockCipher
- 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 interfaceBlockCipher
- 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 interfaceBlockCipher
-
init
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 interfaceBlockCipher
- 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.
-
encryptByte
private byte encryptByte(byte data, int blockOff) Encrypt one byte of data according to CFB mode.- Parameters:
data
- the byte to encryptwhere
- am i in the current block, determines when to resync the block
-
encryptBlock
private int encryptBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, IllegalStateException Do the appropriate processing for CFB IV 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 processing for CFB IV 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.
-