Package org.apache.commons.crypto.stream

Class PositionedCryptoInputStream

java.lang.Object

java.io.InputStream

org.apache.commons.crypto.stream.CryptoInputStream

org.apache.commons.crypto.stream.CtrCryptoInputStream

org.apache.commons.crypto.stream.PositionedCryptoInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.nio.channels.Channel, java.nio.channels.ReadableByteChannel

public class PositionedCryptoInputStream
extends CtrCryptoInputStream

PositionedCryptoInputStream provides the capability to decrypt the stream starting at random position as well as provides the foundation for positioned read for decrypting. This needs a stream cipher mode such as AES CTR mode.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	PositionedCryptoInputStream.CipherState

Field Summary

Fields

Modifier and Type	Field	Description
private java.util.Queue<java.nio.ByteBuffer>	byteBufferPool	DirectBuffer pool
private java.util.Queue<PositionedCryptoInputStream.CipherState>	cipherStatePool	CryptoCipher pool
private java.util.Properties	properties	properties for constructing a CryptoCipher

Fields inherited from class org.apache.commons.crypto.stream.CryptoInputStream

cipher, EOS, inBuffer, input, key, outBuffer, STREAM_BUFFER_SIZE_KEY

Constructor Summary

Constructors

Modifier	Constructor	Description
	PositionedCryptoInputStream(java.util.Properties properties, Input in, byte[] key, byte[] iv, long streamOffset)	Constructs a PositionedCryptoInputStream.
protected	PositionedCryptoInputStream(java.util.Properties properties, Input input, CryptoCipher cipher, int bufferSize, byte[] key, byte[] iv, long streamOffset)	Constructs a PositionedCryptoInputStream.

Method Summary

Modifier and Type	Method	Description
private void	cleanByteBufferPool()	Cleans direct buffer pool
private void	cleanCipherStatePool()	Cleans direct buffer pool
void	close()	Overrides the CryptoInputStream.close().
protected void	decrypt(long position, byte[] buffer, int offset, int length)	Decrypts length bytes in buffer starting at offset.
private void	decrypt(PositionedCryptoInputStream.CipherState state, java.nio.ByteBuffer inByteBuffer, java.nio.ByteBuffer outByteBuffer, byte padding)	Does the decryption using inBuffer as input and outBuffer as output.
private void	decryptBuffer(PositionedCryptoInputStream.CipherState state, java.nio.ByteBuffer inByteBuffer, java.nio.ByteBuffer outByteBuffer)	Does the decryption using inBuffer as input and outBuffer as output.
private java.nio.ByteBuffer	getBuffer()	Gets direct buffer from pool.
private PositionedCryptoInputStream.CipherState	getCipherState()	Gets CryptoCipher from pool.
private byte	postDecryption(PositionedCryptoInputStream.CipherState state, java.nio.ByteBuffer inByteBuffer, long position, byte[] iv)	This method is executed immediately after decryption.
int	read(long position, byte[] buffer, int offset, int length)	Reads up to the specified number of bytes from a given position within a stream and return the number of bytes read.
void	readFully(long position, byte[] buffer)	Reads the specified number of bytes from a given position within a stream.
void	readFully(long position, byte[] buffer, int offset, int length)	Reads the specified number of bytes from a given position within a stream.
private void	resetCipher(PositionedCryptoInputStream.CipherState state, long position, byte[] iv)	Calculates the counter and iv, reset the cipher.
private void	returnToPool(java.nio.ByteBuffer buf)	Returns direct buffer to pool.
private void	returnToPool(PositionedCryptoInputStream.CipherState state)	Returns CryptoCipher to pool.

Methods inherited from class org.apache.commons.crypto.stream.CtrCryptoInputStream

calculateIV, decrypt, decrypt, decryptBuffer, decryptInPlace, decryptMore, getCounter, getInitIV, getPadding, getStreamOffset, getStreamPosition, initCipher, postDecryption, read, resetCipher, resetStreamOffset, seek, setStreamOffset, skip

Methods inherited from class org.apache.commons.crypto.stream.CryptoInputStream

available, checkBufferSize, checkStream, checkStreamCipher, decryptFinal, freeBuffers, freeDirectBuffer, getBufferSize, getBufferSize, getCipher, getInput, getKey, getParams, isOpen, markSupported, read, read

Methods inherited from class java.io.InputStream

mark, read, reset

Methods inherited from class java.lang.Object

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

Field Detail

byteBufferPool

private final java.util.Queue<java.nio.ByteBuffer> byteBufferPool

DirectBuffer pool

cipherStatePool

private final java.util.Queue<PositionedCryptoInputStream.CipherState> cipherStatePool

CryptoCipher pool

properties

private final java.util.Properties properties

properties for constructing a CryptoCipher

Constructor Detail

PositionedCryptoInputStream

public PositionedCryptoInputStream(java.util.Properties properties,
                                   Input in,
                                   byte[] key,
                                   byte[] iv,
                                   long streamOffset)
                            throws java.io.IOException

Constructs a PositionedCryptoInputStream.

Parameters:

properties - The Properties class represents a set of properties.

in - the input data.

key - crypto key for the cipher.

iv - Initialization vector for the cipher.

streamOffset - the start offset in the data.

Throws:

java.io.IOException - if an I/O error occurs.

PositionedCryptoInputStream

protected PositionedCryptoInputStream(java.util.Properties properties,
                                      Input input,
                                      CryptoCipher cipher,
                                      int bufferSize,
                                      byte[] key,
                                      byte[] iv,
                                      long streamOffset)
                               throws java.io.IOException

Constructs a PositionedCryptoInputStream.

Parameters:

properties - the properties of stream

input - the input data.

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:

java.io.IOException - if an I/O error occurs.

Method Detail

cleanByteBufferPool

private void cleanByteBufferPool()

Cleans direct buffer pool

cleanCipherStatePool

private void cleanCipherStatePool()

Cleans direct buffer pool

close

public void close()
           throws java.io.IOException

Overrides the CryptoInputStream.close(). Closes this input stream and releases any system resources associated with the stream.

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.nio.channels.Channel

Specified by:

close in interface java.io.Closeable

Overrides:

close in class CryptoInputStream

Throws:

java.io.IOException - if an I/O error occurs.

decrypt

private void decrypt(PositionedCryptoInputStream.CipherState state,
                     java.nio.ByteBuffer inByteBuffer,
                     java.nio.ByteBuffer outByteBuffer,
                     byte padding)
              throws java.io.IOException

Does the decryption using inBuffer as input and outBuffer as output. Upon return, inBuffer is cleared; the decrypted data starts at outBuffer.position() and ends at outBuffer.limit().

Parameters:

state - the CipherState instance.

inByteBuffer - the input buffer.

outByteBuffer - the output buffer.

padding - the padding.

Throws:

java.io.IOException - if an I/O error occurs.

decrypt

protected void decrypt(long position,
                       byte[] buffer,
                       int offset,
                       int length)
                throws java.io.IOException

Decrypts length bytes in buffer starting at offset. Output is also put into buffer starting at offset. It is thread-safe.

Parameters:

buffer - the buffer into which the data is read.

offset - the start offset in the data.

position - the offset from the start of the stream.

length - the maximum number of bytes to read.

Throws:

java.io.IOException - if an I/O error occurs.

decryptBuffer

private void decryptBuffer(PositionedCryptoInputStream.CipherState state,
                           java.nio.ByteBuffer inByteBuffer,
                           java.nio.ByteBuffer outByteBuffer)
                    throws java.io.IOException

Does the decryption using inBuffer as input and outBuffer as output.

Parameters:

state - the CipherState instance.

inByteBuffer - the input buffer.

outByteBuffer - the output buffer.

Throws:

java.io.IOException - if an I/O error occurs.

getBuffer

private java.nio.ByteBuffer getBuffer()

Gets direct buffer from pool. Caller MUST also call returnToPool(ByteBuffer).

Returns:

the buffer.

See Also:

returnToPool(ByteBuffer)

getCipherState

private PositionedCryptoInputStream.CipherState getCipherState()
                                                        throws java.io.IOException

Gets CryptoCipher from pool. Caller MUST also call returnToPool(CipherState).

Returns:

the CipherState instance.

Throws:

java.io.IOException - if an I/O error occurs.

postDecryption

private byte postDecryption(PositionedCryptoInputStream.CipherState state,
                            java.nio.ByteBuffer inByteBuffer,
                            long position,
                            byte[] iv)

This method is executed immediately after decryption. Check whether cipher should be updated and recalculate padding if needed.

Parameters:

state - the CipherState instance.

inByteBuffer - the input buffer.

position - the offset from the start of the stream.

iv - the iv.

Returns:

the padding.

read

public int read(long position,
                byte[] buffer,
                int offset,
                int length)
         throws java.io.IOException

Reads up to the specified number of bytes from a given position within a stream and return the number of bytes read. This does not change the current offset of the stream, and is thread-safe.

Parameters:

buffer - the buffer into which the data is read.

length - the maximum number of bytes to read.

offset - the start offset in the data.

position - the offset from the start of the stream.

Returns:

int the total number of decrypted data bytes read into the buffer.

Throws:

java.io.IOException - if an I/O error occurs.

readFully

public void readFully(long position,
                      byte[] buffer)
               throws java.io.IOException

Reads the specified number of bytes from a given position within a stream. This does not change the current offset of the stream and is thread-safe.

Parameters:

position - the offset from the start of the stream.

buffer - the buffer into which the data is read.

Throws:

java.io.IOException - if an I/O error occurs.

readFully

public void readFully(long position,
                      byte[] buffer,
                      int offset,
                      int length)
               throws java.io.IOException

Reads the specified number of bytes from a given position within a stream. This does not change the current offset of the stream and is thread-safe.

Parameters:

buffer - the buffer into which the data is read.

length - the maximum number of bytes to read.

offset - the start offset in the data.

position - the offset from the start of the stream.

Throws:

java.io.IOException - if an I/O error occurs.

resetCipher

private void resetCipher(PositionedCryptoInputStream.CipherState state,
                         long position,
                         byte[] iv)

Calculates the counter and iv, reset the cipher.

Parameters:

state - the CipherState instance.

position - the offset from the start of the stream.

iv - the iv.

returnToPool

private void returnToPool(java.nio.ByteBuffer buf)

Returns direct buffer to pool.

Parameters:

buf - the buffer.

returnToPool

private void returnToPool(PositionedCryptoInputStream.CipherState state)

Returns CryptoCipher to pool.

Parameters:

state - the CipherState instance.