net.java.truevfs.comp.zip.crypto

Class CipherReadOnlyChannel

java.lang.Object

net.java.truecommons.io.AbstractSeekableChannel

net.java.truecommons.io.DecoratingSeekableChannel

net.java.truecommons.io.ReadOnlyChannel

net.java.truevfs.comp.zip.crypto.CipherReadOnlyChannel

All Implemented Interfaces:

Closeable, AutoCloseable, ByteChannel, Channel, ReadableByteChannel, SeekableByteChannel, WritableByteChannel

@NotThreadSafe
public final class CipherReadOnlyChannel
extends net.java.truecommons.io.ReadOnlyChannel

Provides buffered random read-only access to the plain text of an encrypted file. Note that this channel maintains its own virtual file pointer.

Author:

Christian Schlichtherle

See Also:

CipherOutputStream

Field Summary

Fields inherited from class net.java.truecommons.io.DecoratingSeekableChannel

channel

Constructor Summary

Constructors

Constructor and Description
CipherReadOnlyChannel(SeekableBlockCipher cipher, SeekableByteChannel channel) Constructs a new cipher read-only channel.
CipherReadOnlyChannel(SeekableBlockCipher cipher, SeekableByteChannel channel, int bufferSize) Constructs a new cipher read-only channel.

Method Summary

Modifier and Type	Method and Description
byte[]	mac(Mac mac) Returns the authentication code of the encrypted data in this cipher read-only channel using the given Message Authentication Code (MAC) object.
long	position()
SeekableByteChannel	position(long pos)
int	read(ByteBuffer dst)

Methods inherited from class net.java.truecommons.io.ReadOnlyChannel

truncate, write

Methods inherited from class net.java.truecommons.io.DecoratingSeekableChannel

close, isOpen, size, toString

Methods inherited from class net.java.truecommons.io.AbstractSeekableChannel

checkOpen

Methods inherited from class java.lang.Object

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

Constructor Detail

CipherReadOnlyChannel

@CreatesObligation
public CipherReadOnlyChannel(SeekableBlockCipher cipher,
                                                @WillCloseWhenClosed
                                                SeekableByteChannel channel)

Constructs a new cipher read-only channel.

Parameters:

cipher - the initialized, seekable block cipher.

channel - the seekable byte channel.

CipherReadOnlyChannel

@CreatesObligation
public CipherReadOnlyChannel(SeekableBlockCipher cipher,
                                                @WillCloseWhenClosed
                                                SeekableByteChannel channel,
                                                int bufferSize)

Constructs a new cipher read-only channel.

Parameters:

cipher - the seekable block cipher.

channel - the seekable byte channel.

bufferSize - the size of the byte buffer. The value gets rounded down to a multiple of the cipher's blocksize or the cipher's blocksize, whatever is larger.

Method Detail

mac

public byte[] mac(Mac mac)
           throws IOException

Returns the authentication code of the encrypted data in this cipher read-only channel using the given Message Authentication Code (MAC) object. It is safe to call this method multiple times to detect if the file has been tampered with meanwhile.

Parameters:

mac - a properly initialized MAC object.

Returns:

A byte array with the authentication code.

Throws:

IOException - on any I/O error.

position

public long position()
              throws IOException

Specified by:

position in interface SeekableByteChannel

Overrides:

position in class net.java.truecommons.io.DecoratingSeekableChannel

Throws:

IOException

position

public SeekableByteChannel position(long pos)
                             throws IOException

Specified by:

position in interface SeekableByteChannel

Overrides:

position in class net.java.truecommons.io.DecoratingSeekableChannel

Throws:

IOException

read

public int read(ByteBuffer dst)
         throws IOException

Specified by:

read in interface ReadableByteChannel

Specified by:

read in interface SeekableByteChannel

Overrides:

read in class net.java.truecommons.io.DecoratingSeekableChannel

Throws:

IOException