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:

Closeable, AutoCloseable, Channel, 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.

Field Summary

Fields inherited from class CryptoInputStream

EOS, STREAM_BUFFER_SIZE_KEY

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
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.
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.

Methods inherited from class CtrCryptoInputStream

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

Methods inherited from class CryptoInputStream

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

Methods inherited from class InputStream

mark, read, reset

Methods inherited from class Object

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

Constructor Details

PositionedCryptoInputStream

public PositionedCryptoInputStream(Properties properties,
 Input in,
 byte[] key,
 byte[] iv,
 long streamOffset)
                            throws 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:

IOException - if an I/O error occurs.

PositionedCryptoInputStream

protected PositionedCryptoInputStream(Properties properties,
 Input input,
 CryptoCipher cipher,
 int bufferSize,
 byte[] key,
 byte[] iv,
 long streamOffset)
                               throws 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:

IOException - if an I/O error occurs.

Method Details

close

public void close()
           throws IOException

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

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Channel

Specified by:

close in interface Closeable

Overrides:

close in class CryptoInputStream

Throws:

IOException - if an I/O error occurs.

decrypt

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

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

Parameters:

position - the offset from the start of the stream.

buffer - the buffer into which the data is read.

offset - the start offset in the data.

length - the maximum number of bytes to read.

Throws:

IOException - if an I/O error occurs.

read

public int read(long position,
 byte[] buffer,
 int offset,
 int length)
         throws 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:

position - the offset from the start of the stream.

buffer - the buffer into which the data is read.

offset - the start offset in the data.

length - the maximum number of bytes to read.

Returns:

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

Throws:

IOException - if an I/O error occurs.

readFully

public void readFully(long position,
 byte[] buffer)
               throws 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:

IOException - if an I/O error occurs.

readFully

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

offset - the start offset in the data.

length - the maximum number of bytes to read.

Throws:

IOException - if an I/O error occurs.