Class CtrCryptoOutputStream

java.lang.Object

java.io.OutputStream

org.apache.commons.crypto.stream.CryptoOutputStream

org.apache.commons.crypto.stream.CtrCryptoOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable, Channel, WritableByteChannel

public class CtrCryptoOutputStream
extends CryptoOutputStream

CtrCryptoOutputStream encrypts data. It is not thread-safe. AES CTR mode is required in order to ensure that the plain text and cipher text have a 1:1 mapping. The encryption is buffer based. The key points of the encryption are (1) calculating counter and (2) padding through stream position.

counter = base + pos/(algorithm blocksize); padding = pos%(algorithm blocksize);

The underlying stream offset is maintained as state.

This class should only be used with blocking sinks. Using this class to wrap a non-blocking sink may lead to high CPU usage.

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	cipherReset	Flag to mark whether the cipher has been reset
private final byte[]	initIV	The initial IV.
private final byte[]	iv	Initialization vector for the cipher.
private byte	padding	Padding = pos%(algorithm blocksize); Padding is put into CryptoOutputStream.inBuffer before any other data goes in.
private long	streamOffset	Underlying stream offset.

Fields inherited from class CryptoOutputStream

cipher, inBuffer, key, outBuffer, output

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	CtrCryptoOutputStream(OutputStream out, CryptoCipher cipher, int bufferSize, byte[] key, byte[] iv)	Constructs a CtrCryptoOutputStream.
protected	CtrCryptoOutputStream(OutputStream outputStream, CryptoCipher cipher, int bufferSize, byte[] key, byte[] iv, long streamOffset)	Constructs a CtrCryptoOutputStream.
protected	CtrCryptoOutputStream(WritableByteChannel channel, CryptoCipher cipher, int bufferSize, byte[] key, byte[] iv)	Constructs a CtrCryptoOutputStream.
protected	CtrCryptoOutputStream(WritableByteChannel channel, CryptoCipher cipher, int bufferSize, byte[] key, byte[] iv, long streamOffset)	Constructs a CtrCryptoOutputStream.
	CtrCryptoOutputStream(Properties props, OutputStream out, byte[] key, byte[] iv)	Constructs a CtrCryptoOutputStream.
	CtrCryptoOutputStream(Properties properties, OutputStream outputStream, byte[] key, byte[] iv, long streamOffset)	Constructs a CtrCryptoOutputStream.
	CtrCryptoOutputStream(Properties props, WritableByteChannel out, byte[] key, byte[] iv)	Constructs a CtrCryptoOutputStream.
	CtrCryptoOutputStream(Properties properties, WritableByteChannel channel, byte[] key, byte[] iv, long streamOffset)	Constructs a CtrCryptoOutputStream.
protected	CtrCryptoOutputStream(Output output, CryptoCipher cipher, int bufferSize, byte[] key, byte[] iv)	Constructs a CtrCryptoOutputStream.
protected	CtrCryptoOutputStream(Output output, CryptoCipher cipher, int bufferSize, byte[] key, byte[] iv, long streamOffset)	Constructs a CtrCryptoOutputStream.

Method Summary

Modifier and Type	Method	Description
protected void	encrypt()	Does the encryption, input is CryptoOutputStream.inBuffer and output is CryptoOutputStream.outBuffer.
private void	encryptBuffer(ByteBuffer out)	Does the encryption if the ByteBuffer data.
protected void	encryptFinal()	Does final encryption of the last data.
protected long	getStreamOffset()	Get the underlying stream offset
protected void	initCipher()	Overrides the CryptoOutputStream.initCipher().
private void	resetCipher()	Resets the CryptoOutputStream.cipher: calculate counter and padding.
protected void	setStreamOffset(long streamOffset)	Set the underlying stream offset

Methods inherited from class CryptoOutputStream

checkStream, close, flush, freeBuffers, getBufferSize, getCipher, getInBuffer, getOutBuffer, isOpen, write, write, write

Methods inherited from class OutputStream

write

Methods inherited from class Object

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

Field Details

streamOffset

private long streamOffset

Underlying stream offset.

initIV

private final byte[] initIV

The initial IV.

iv

private final byte[] iv

Initialization vector for the cipher.

padding

private byte padding

Padding = pos%(algorithm blocksize); Padding is put into CryptoOutputStream.inBuffer before any other data goes in. The purpose of padding is to put input data at proper position.

cipherReset

private boolean cipherReset

Flag to mark whether the cipher has been reset

Constructor Details

CtrCryptoOutputStream

protected CtrCryptoOutputStream(Output output,
 CryptoCipher cipher,
 int bufferSize,
 byte[] key,
 byte[] iv)
                         throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

output - the Output instance.

cipher - the CryptoCipher instance.

bufferSize - the bufferSize.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

protected CtrCryptoOutputStream(Output output,
 CryptoCipher cipher,
 int bufferSize,
 byte[] key,
 byte[] iv,
 long streamOffset)
                         throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

output - the output stream.

cipher - the CryptoCipher instance.

bufferSize - the bufferSize.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

streamOffset - the start offset in the data.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

protected CtrCryptoOutputStream(OutputStream out,
 CryptoCipher cipher,
 int bufferSize,
 byte[] key,
 byte[] iv)
                         throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

out - the output stream.

cipher - the CryptoCipher instance.

bufferSize - the bufferSize.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

protected CtrCryptoOutputStream(OutputStream outputStream,
 CryptoCipher cipher,
 int bufferSize,
 byte[] key,
 byte[] iv,
 long streamOffset)
                         throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

outputStream - the output stream.

cipher - the CryptoCipher instance.

bufferSize - the bufferSize.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

streamOffset - the start offset in the data.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

public CtrCryptoOutputStream(Properties props,
 OutputStream out,
 byte[] key,
 byte[] iv)
                      throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

props - The Properties class represents a set of properties.

out - the output stream.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

public CtrCryptoOutputStream(Properties properties,
 OutputStream outputStream,
 byte[] key,
 byte[] iv,
 long streamOffset)
                      throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

properties - The Properties class represents a set of properties.

outputStream - the output stream.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

streamOffset - the start offset in the data.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

public CtrCryptoOutputStream(Properties props,
 WritableByteChannel out,
 byte[] key,
 byte[] iv)
                      throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

props - The Properties class represents a set of properties.

out - the WritableByteChannel instance.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

public CtrCryptoOutputStream(Properties properties,
 WritableByteChannel channel,
 byte[] key,
 byte[] iv,
 long streamOffset)
                      throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

properties - The Properties class represents a set of properties.

channel - the WritableByteChannel instance.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

streamOffset - the start offset in the data.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

protected CtrCryptoOutputStream(WritableByteChannel channel,
 CryptoCipher cipher,
 int bufferSize,
 byte[] key,
 byte[] iv)
                         throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

channel - the WritableByteChannel instance.

cipher - the CryptoCipher instance.

bufferSize - the bufferSize.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

Throws:

IOException - if an I/O error occurs.

CtrCryptoOutputStream

protected CtrCryptoOutputStream(WritableByteChannel channel,
 CryptoCipher cipher,
 int bufferSize,
 byte[] key,
 byte[] iv,
 long streamOffset)
                         throws IOException

Constructs a CtrCryptoOutputStream.

Parameters:

channel - the WritableByteChannel instance.

cipher - the CryptoCipher instance.

bufferSize - the bufferSize.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

streamOffset - the start offset in the data.

Throws:

IOException - if an I/O error occurs.

Method Details

encrypt

protected void encrypt()
                throws IOException

Does the encryption, input is CryptoOutputStream.inBuffer and output is CryptoOutputStream.outBuffer.

Overrides:

encrypt in class CryptoOutputStream

Throws:

IOException - if an I/O error occurs.

encryptBuffer

private void encryptBuffer(ByteBuffer out)
                    throws IOException

Does the encryption if the ByteBuffer data.

Parameters:

out - the output ByteBuffer.

Throws:

IOException - if an I/O error occurs.

encryptFinal

protected void encryptFinal()
                     throws IOException

Does final encryption of the last data.

Overrides:

encryptFinal in class CryptoOutputStream

Throws:

IOException - if an I/O error occurs.

getStreamOffset

protected long getStreamOffset()

Get the underlying stream offset

Returns:

the underlying stream offset

initCipher

protected void initCipher()

Overrides the CryptoOutputStream.initCipher(). Initializes the cipher.

Overrides:

initCipher in class CryptoOutputStream

resetCipher

private void resetCipher()
                  throws IOException

Resets the CryptoOutputStream.cipher: calculate counter and padding.

Throws:

IOException - if an I/O error occurs.

setStreamOffset

protected void setStreamOffset(long streamOffset)

Set the underlying stream offset

Parameters:

streamOffset - the underlying stream offset