Package org.apache.poi.poifs.crypt

Class ChunkedCipherInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

org.apache.poi.util.LittleEndianInputStream

org.apache.poi.poifs.crypt.ChunkedCipherInputStream

All Implemented Interfaces:

Closeable, AutoCloseable, LittleEndianInput

@Internal
public abstract class ChunkedCipherInputStream
extends LittleEndianInputStream

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor	Description
ChunkedCipherInputStream(InputStream stream, long size, int chunkSize)
ChunkedCipherInputStream(InputStream stream, long size, int chunkSize, int initialPos)

Method Summary

Modifier and Type	Method	Description
int	available()
protected byte[]	getChunk()
protected int	getChunkMask()
protected byte[]	getPlain()
long	getPos()
final Cipher	initCipherForBlock(int block)
protected abstract Cipher	initCipherForBlock(Cipher existing, int block)
protected int	invokeCipher(int totalBytes, boolean doFinal)	Helper function for overriding the cipher invocation, i.e.
void	mark(int readlimit)
boolean	markSupported()
int	read()
int	read(byte[] b, int off, int len)
void	readPlain(byte[] b, int off, int len)	Used when BIFF header fields (sid, size) are being read.
void	reset()
void	setNextRecordSize(int recordSize)	Some ciphers (actually just XOR) are based on the record size, which needs to be set before decryption
long	skip(long n)
void	skipFully(long len)	Skips by moving the position, as the size of the stream is known.

Methods inherited from class org.apache.poi.util.LittleEndianInputStream

getReadIndex, readByte, readDouble, readFloat, readFully, readFully, readInt, readLong, readShort, readUByte, readUInt, readUShort, skipFully

Methods inherited from class java.io.FilterInputStream

close, read

Methods inherited from class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ChunkedCipherInputStream

public ChunkedCipherInputStream(InputStream stream,
 long size,
 int chunkSize)
                         throws GeneralSecurityException

Throws:

GeneralSecurityException

ChunkedCipherInputStream

public ChunkedCipherInputStream(InputStream stream,
 long size,
 int chunkSize,
 int initialPos)
                         throws GeneralSecurityException

Throws:

GeneralSecurityException

Method Details

initCipherForBlock

public final Cipher initCipherForBlock(int block)
                                throws IOException,
GeneralSecurityException

Throws:

IOException

GeneralSecurityException

initCipherForBlock

protected abstract Cipher initCipherForBlock(Cipher existing,
 int block)
                                      throws GeneralSecurityException

Throws:

GeneralSecurityException

read

public int read()
         throws IOException

Overrides:

read in class LittleEndianInputStream

Throws:

IOException

read

public int read(byte[] b,
 int off,
 int len)
         throws IOException

Overrides:

read in class LittleEndianInputStream

Throws:

IOException

skip

public long skip(long n)

Overrides:

skip in class LittleEndianInputStream

skipFully

public void skipFully(long len)
               throws IOException

Skips by moving the position, as the size of the stream is known. The skipped chunks are not decrypted.

Overrides:

skipFully in class LittleEndianInputStream

Parameters:

len - the number of bytes to skip

Throws:

IOException - if the stream can't be read

available

public int available()

Specified by:

available in interface LittleEndianInput

Overrides:

available in class LittleEndianInputStream

markSupported

public boolean markSupported()

Overrides:

markSupported in class FilterInputStream

mark

public void mark(int readlimit)

Overrides:

mark in class LittleEndianInputStream

reset

public void reset()

Overrides:

reset in class LittleEndianInputStream

getChunkMask

protected int getChunkMask()

invokeCipher

protected int invokeCipher(int totalBytes,
 boolean doFinal)
                    throws GeneralSecurityException

Helper function for overriding the cipher invocation, i.e. XOR doesn't use a cipher and uses its own implementation

Throws:

GeneralSecurityException

readPlain

public void readPlain(byte[] b,
 int off,
 int len)

Used when BIFF header fields (sid, size) are being read. The internal Cipher instance must step even when unencrypted bytes are read

Specified by:

readPlain in interface LittleEndianInput

Overrides:

readPlain in class LittleEndianInputStream

Parameters:

b - the byte array to receive the bytes

off - the start offset into the byte array

len - the amount of bytes to fill

setNextRecordSize

public void setNextRecordSize(int recordSize)

Some ciphers (actually just XOR) are based on the record size, which needs to be set before decryption

Parameters:

recordSize - the size of the next record

getChunk

protected byte[] getChunk()

Returns:

the chunk bytes

getPlain

protected byte[] getPlain()

Returns:

the plain bytes

getPos

public long getPos()

Returns:

the absolute position in the stream