client
Class Client

java.lang.Object
  client.Client

All Implemented Interfaces:

ClientInterface

public final class Client
extends java.lang.Object
implements ClientInterface

The Client used to anonymize data (e. g. from a user's application) via a cascade of mixes. Follows the "everything is a stream" concept. See architectureInterfaces.ClientInterface. From a user perspective, this Client behaves quite equal to a socket (java.net.Socket) and therefore abstracts from the underlying technique.

Author:

Karl-Peter Fuchs

Nested Class Summary

private class

Client.CascadeInputOutputHandler Internal class used to communicate with the mix cascade.

Field Summary

private java.net.InetAddress	CASCADE_ADDRESS Address of the cascade (cascade's first mix) used to transmit messages.
private int	CASCADE_PORT Port number of the cascade (cascade's first mix) used to transmit messages.
private int	CASCADE_TIMEOUT Period of time, a client waits for the cascade to accept his connection request in ms.
private ClientInputStream	clientInputStream ClientInputStream for client communication.
private ClientOutputStream	clientOutputStream ClientOutputStream for client communication.
private Cryptography	cryptography Used to perform cryptographic operations (decrypting, encrypting, generating session keys, MACs... ).
private static InternalInformationPortController	internalInformationPort Reference on component InternalInformationPort.
private boolean	isChannelEstablished Indicates whether a channel to the cascade is established or not.
private boolean	isDisconnectRequested Indicates whether the user (application) called disconnect() and therefore wants to release his/its connection to the cascade.
private boolean	isFirstWriteDone Indicates whether the user (application) has already put data in the OutputStream (used to start the ).
private boolean	isReadMethodReturnForced Indicates whether the method receiveDataFromCascade() shall return all data received so far, no matter how much data it is waiting for (since no further data can be expected from the cascade).
private boolean	isReadMethodWaiting Indicates whether the method receiveDataFromCascade() is waiting for new data from the cascade (used for synchronization).
private boolean	isWriteMethodWaiting Indicates whether the method putInSendBuffer() is waiting for the CascadeInputOutputHandler to send the data it gave to it (used for synchronization).
private static java.util.logging.Logger	LOGGER Logger used to log and display information.
private int	MAX_CHANNEL_ESTABLISH_MESSAGE_LENGTH Maximum amount of data (payload), that can be stored in a ChannelEstablishMessage.
private int	MAX_CHANNEL_MESSAGE_LENGTH Maximum amount of data (payload), that can be stored in a ChannelMessage.
private MessageGenerator	messageGenerator Used to generate message the mixes are capable of processing.
private java.net.Socket	mix Socket for mix communication.
private java.io.InputStream	mixInputStream MixInputStream for mix communication.
private java.io.OutputStream	mixOutputStream MixOutputStream for mix communication.
private long	REACTION_TIME Period of time to wait between the receival of a Reply (from the cascade) and the sending of a new Request for the user (application) to react (= add new data to be sent).
private int	RECEIVE_BUFFER_SIZE Initial size of the receiveBuffer.
private java.nio.ByteBuffer	receiveBuffer Buffer to store incoming data from the cascade.
private java.lang.Object	receiveBufferSynchronizer Object used to synchronize the receiveBuffer.
private int	SEND_BUFFER_SIZE Initial size of the sendBuffer.
private java.nio.ByteBuffer	sendBuffer Buffer to store data that shall be sent to the cascade.

Constructor Summary

Client()
Creates a new Client which receives the keys (to encrypt messages) from the cascade's mixes automatically.

Client(java.security.Key[] publicKeysOfMixes)
Creates a new Client which uses the bypassed keys to encrypt messages.

Method Summary

void	connect() Connects client to the mix cascade, specified in property file.
void	disconnect() Disconnects client from mix cascade.
ClientInputStream	getInputStream() Returns an InputStream that can be used to receive data anonymously.
ClientOutputStream	getOutputStream() Returns an OutputStream that can be used to send data anonymously.
private static java.lang.String	getProperty(java.lang.String key) Simply used to shorten method calls (calls internalInformationPort.getProperty(key)).
private static java.security.PublicKey[]	getPublicKeys() Retrieves the public keys of all mixes in the cascade (address of first mix must be specified in property file) for later encryption.
protected void	putInSendBuffer(byte[] data) Adds the bypassed data to the sendBuffer (from where it gets transmitted to the mix cascade by CascadeInputOutputHandler ).
protected byte[]	receiveDataFromCascade(int amoutOfDataNeeded) Tries to read amoutOfDataNeeded bytes from the mix cascade.
private void	sendMessage(byte[] dataToSend) Sends the bypassed data to the mix cascade.

Methods inherited from class java.lang.Object

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

Field Detail

internalInformationPort

private static InternalInformationPortController internalInformationPort

Reference on component InternalInformationPort. Used to display and/or log data and read general settings.

LOGGER

private static final java.util.logging.Logger LOGGER

Logger used to log and display information.

CASCADE_ADDRESS

private final java.net.InetAddress CASCADE_ADDRESS

Address of the cascade (cascade's first mix) used to transmit messages.

CASCADE_PORT

private final int CASCADE_PORT

Port number of the cascade (cascade's first mix) used to transmit messages.

CASCADE_TIMEOUT

private final int CASCADE_TIMEOUT

Period of time, a client waits for the cascade to accept his connection request in ms.

MAX_CHANNEL_ESTABLISH_MESSAGE_LENGTH

private final int MAX_CHANNEL_ESTABLISH_MESSAGE_LENGTH

Maximum amount of data (payload), that can be stored in a ChannelEstablishMessage.

MAX_CHANNEL_MESSAGE_LENGTH

private final int MAX_CHANNEL_MESSAGE_LENGTH

Maximum amount of data (payload), that can be stored in a ChannelMessage.

REACTION_TIME

private final long REACTION_TIME

Period of time to wait between the receival of a Reply (from the cascade) and the sending of a new Request for the user (application) to react (= add new data to be sent). Note: If no new data or a disconnect request has arrived during this period of time, a dummy message is sent.

mix

private java.net.Socket mix

Socket for mix communication.

clientOutputStream

private ClientOutputStream clientOutputStream

ClientOutputStream for client communication.

clientInputStream

private ClientInputStream clientInputStream

ClientInputStream for client communication.

mixOutputStream

private java.io.OutputStream mixOutputStream

MixOutputStream for mix communication.

mixInputStream

private java.io.InputStream mixInputStream

MixInputStream for mix communication.

receiveBuffer

private java.nio.ByteBuffer receiveBuffer

Buffer to store incoming data from the cascade.

receiveBufferSynchronizer

private java.lang.Object receiveBufferSynchronizer

Object used to synchronize the receiveBuffer.

Note: This requires a special object, since the used ByteBuffer-object may change during runtime (In Java, ByteBuffers can't be resized. Nevertheless, the buffer's size must be adjusted in a few cases (when unexpected large write-requests occur)). Therefore, a permanently available object must be present.

See Also:

receiveBuffer

sendBuffer

private java.nio.ByteBuffer sendBuffer

Buffer to store data that shall be sent to the cascade.

RECEIVE_BUFFER_SIZE

private final int RECEIVE_BUFFER_SIZE

Initial size of the receiveBuffer.

See Also:

receiveBuffer

SEND_BUFFER_SIZE

private final int SEND_BUFFER_SIZE

Initial size of the sendBuffer.

See Also:

sendBuffer

isChannelEstablished

private boolean isChannelEstablished

Indicates whether a channel to the cascade is established or not.

isReadMethodWaiting

private boolean isReadMethodWaiting

Indicates whether the method receiveDataFromCascade() is waiting for new data from the cascade (used for synchronization).

See Also:

receiveDataFromCascade(int)

isReadMethodReturnForced

private boolean isReadMethodReturnForced

Indicates whether the method receiveDataFromCascade() shall return all data received so far, no matter how much data it is waiting for (since no further data can be expected from the cascade).

See Also:

receiveDataFromCascade(int)

isWriteMethodWaiting

private boolean isWriteMethodWaiting

Indicates whether the method putInSendBuffer() is waiting for the CascadeInputOutputHandler to send the data it gave to it (used for synchronization).

See Also:

putInSendBuffer(byte[])

isDisconnectRequested

private boolean isDisconnectRequested

Indicates whether the user (application) called disconnect() and therefore wants to release his/its connection to the cascade.

See Also:

disconnect()

isFirstWriteDone

private boolean isFirstWriteDone

Indicates whether the user (application) has already put data in the OutputStream (used to start the ). called disconnect() and therefore wants to release his/its connection to the CascadeInputOutputHandler at the right time.

See Also:

disconnect()

cryptography

private Cryptography cryptography

Used to perform cryptographic operations (decrypting, encrypting, generating session keys, MACs... ).

messageGenerator

private MessageGenerator messageGenerator

Used to generate message the mixes are capable of processing.

Constructor Detail

Client

public Client(java.security.Key[] publicKeysOfMixes)

Creates a new Client which uses the bypassed keys to encrypt messages.

Parameters:

publicKeysOfMixes - Public keys of the cascade's mixes (used to encrypt messages).

Client

public Client()

Creates a new Client which receives the keys (to encrypt messages) from the cascade's mixes automatically.

Method Detail

getPublicKeys

private static java.security.PublicKey[] getPublicKeys()

Retrieves the public keys of all mixes in the cascade (address of first mix must be specified in property file) for later encryption.

Returns:

The public keys of all mixes in the cascade.

getInputStream

public ClientInputStream getInputStream()

Returns an InputStream that can be used to receive data anonymously.

Specified by:

getInputStream in interface ClientInterface

Returns:

InputStream that can be used to receive data anonymously.

Throws:

java.io.IOException - I/O problem occurred.

getOutputStream

public ClientOutputStream getOutputStream()

Returns an OutputStream that can be used to send data anonymously.

Specified by:

getOutputStream in interface ClientInterface

Returns:

OutputStream that can be used to send data anonymously.

Throws:

java.io.IOException - I/O problem occurred.

connect

public void connect()
             throws java.io.IOException

Connects client to the mix cascade, specified in property file.

Specified by:

connect in interface ClientInterface

Throws:

java.io.IOException - I/O problem occurred.

disconnect

public void disconnect()
                throws java.io.IOException

Disconnects client from mix cascade.

Specified by:

disconnect in interface ClientInterface

Throws:

java.io.IOException - I/O problem occurred.

putInSendBuffer

protected void putInSendBuffer(byte[] data)

Adds the bypassed data to the sendBuffer (from where it gets transmitted to the mix cascade by CascadeInputOutputHandler ). Blocks until all data is written (if data doesn't fit in buffer).

Parameters:

data - Data to be put in sendBuffer.

sendMessage

private void sendMessage(byte[] dataToSend)

Sends the bypassed data to the mix cascade. Called by CascadeInputOutputHandler.

Parameters:

dataToSend - Data to be sent.

receiveDataFromCascade

protected byte[] receiveDataFromCascade(int amoutOfDataNeeded)

Tries to read amoutOfDataNeeded bytes from the mix cascade. Blocks until amoutOfDataNeeded bytes are available, or no further data can be expected from the corresponding communication partner.

Parameters:

amoutOfDataNeeded - Number of bytes that shall be read.

Returns:

Read data.

getProperty

private static java.lang.String getProperty(java.lang.String key)

Simply used to shorten method calls (calls internalInformationPort.getProperty(key)). Returns the property with the specified key from the property file.

Parameters:

key - The property key.

Returns:

The property with the specified key in the property file.