CipherInputStream

public class CipherInputStream
extends FilterInputStream

java.lang.Object
   ↳ java.io.InputStream
     ↳ java.io.FilterInputStream
       ↳ javax.crypto.CipherInputStream


A CipherInputStream is composed of an InputStream and a Cipher so that read() methods return data that are read in from the underlying InputStream but have been additionally processed by the Cipher. The Cipher must be fully initialized before being used by a CipherInputStream.

For example, if the Cipher is initialized for decryption, the CipherInputStream will attempt to read in data and decrypt them, before returning the decrypted data.

This class adheres strictly to the semantics, especially the failure semantics, of its ancestor classes java.io.FilterInputStream and java.io.InputStream. This class has exactly those methods specified in its ancestor classes, and overrides them all. Moreover, this class catches all exceptions that are not thrown by its ancestor classes. In particular, the skip method skips, and the available method counts only data that have been processed by the encapsulated Cipher.

It is crucial for a programmer using this class not to use methods that are not defined or overriden in this class (such as a new method or constructor that is later added to one of the super classes), because the design and implementation of those methods are unlikely to have considered security impact with regard to CipherInputStream.

Summary

Inherited fields

protected InputStream in

The input stream to be filtered.

Public constructors

CipherInputStream(InputStream is, Cipher c)

Constructs a CipherInputStream from an InputStream and a Cipher.

Protected constructors

CipherInputStream(InputStream is)

Constructs a CipherInputStream from an InputStream without specifying a Cipher.

Public methods

int available()

Returns the number of bytes that can be read from this input stream without blocking.

void close()

Closes this input stream and releases any system resources associated with the stream.

boolean markSupported()

Tests if this input stream supports the mark and reset methods, which it does not.

int read()

Reads the next byte of data from this input stream.

int read(byte[] b, int off, int len)

Reads up to len bytes of data from this input stream into an array of bytes.

int read(byte[] b)

Reads up to b.length bytes of data from this input stream into an array of bytes.

long skip(long n)

Skips n bytes of input from the bytes that can be read from this input stream without blocking.

Inherited methods

int available()

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.

void close()

Closes this input stream and releases any system resources associated with the stream.

void mark(int readlimit)

Marks the current position in this input stream.

boolean markSupported()

Tests if this input stream supports the mark and reset methods.

int read()

Reads the next byte of data from this input stream.

int read(byte[] b, int off, int len)

Reads up to len bytes of data from this input stream into an array of bytes.

int read(byte[] b)

Reads up to b.length bytes of data from this input stream into an array of bytes.

void reset()

Repositions this stream to the position at the time the mark method was last called on this input stream.

long skip(long n)

Skips over and discards n bytes of data from the input stream.

int available()

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking, which may be 0, or 0 when end of stream is detected.

void close()

Closes this input stream and releases any system resources associated with the stream.

void mark(int readlimit)

Marks the current position in this input stream.

boolean markSupported()

Tests if this input stream supports the mark and reset methods.

static InputStream nullInputStream()

Returns a new InputStream that reads no bytes.

int read(byte[] b)

Reads some number of bytes from the input stream and stores them into the buffer array b.

abstract int read()

Reads the next byte of data from the input stream.

int read(byte[] b, int off, int len)

Reads up to len bytes of data from the input stream into an array of bytes.

byte[] readAllBytes()

Reads all remaining bytes from the input stream.

int readNBytes(byte[] b, int off, int len)

Reads the requested number of bytes from the input stream into the given byte array.

byte[] readNBytes(int len)

Reads up to a specified number of bytes from the input stream.

void reset()

Repositions this stream to the position at the time the mark method was last called on this input stream.

long skip(long n)

Skips over and discards n bytes of data from this input stream.

void skipNBytes(long n)

Skips over and discards exactly n bytes of data from this input stream.

long transferTo(OutputStream out)

Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read.

Object clone()

Creates and returns a copy of this object.

boolean equals(Object obj)

Indicates whether some other object is "equal to" this one.

void finalize()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

final Class<?> getClass()

Returns the runtime class of this Object.

int hashCode()

Returns a hash code value for the object.

final void notify()

Wakes up a single thread that is waiting on this object's monitor.

final void notifyAll()

Wakes up all threads that are waiting on this object's monitor.

String toString()

Returns a string representation of the object.

final void wait(long timeoutMillis, int nanos)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait(long timeoutMillis)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait()

Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

abstract void close()

Closes this stream and releases any system resources associated with it.

abstract void close()

Closes this resource, relinquishing any underlying resources.

Public constructors

CipherInputStream

Added in API level 1
public CipherInputStream (InputStream is, 
                Cipher c)

Constructs a CipherInputStream from an InputStream and a Cipher.
Note: if the specified input stream or cipher is null, a NullPointerException may be thrown later when they are used.

Parameters
is InputStream: the to-be-processed input stream

c Cipher: an initialized Cipher object

Protected constructors

CipherInputStream

Added in API level 1
protected CipherInputStream (InputStream is)

Constructs a CipherInputStream from an InputStream without specifying a Cipher. This has the effect of constructing a CipherInputStream using a NullCipher.
Note: if the specified input stream is null, a NullPointerException may be thrown later when it is used.

Parameters
is InputStream: the to-be-processed input stream

Public methods

available

Added in API level 1
public int available ()

Returns the number of bytes that can be read from this input stream without blocking. The available method of InputStream returns 0. This method should be overridden by subclasses.

Returns
int the number of bytes that can be read from this input stream without blocking.

Throws
IOException if an I/O error occurs.

close

Added in API level 1
public void close ()

Closes this input stream and releases any system resources associated with the stream.

The close method of CipherInputStream calls the close method of its underlying input stream.

Throws
IOException if an I/O error occurs.

markSupported

Added in API level 1
public boolean markSupported ()

Tests if this input stream supports the mark and reset methods, which it does not.

Returns
boolean false, since this class does not support the mark and reset methods.

read

Added in API level 1
public int read ()

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Returns
int the next byte of data, or -1 if the end of the stream is reached.

Throws
IOException if an I/O error occurs.

read

Added in API level 1
public int read (byte[] b, 
                int off, 
                int len)

Reads up to len bytes of data from this input stream into an array of bytes. This method blocks until some input is available. If the first argument is null, up to len bytes are read and discarded.

Parameters
b byte: the buffer into which the data is read.

off int: the start offset in the destination array buf

len int: the maximum number of bytes read.

Returns
int the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws
IOException if an I/O error occurs.

See also:

read

Added in API level 1
public int read (byte[] b)

Reads up to b.length bytes of data from this input stream into an array of bytes.

The read method of InputStream calls the read method of three arguments with the arguments b, 0, and b.length.

Parameters
b byte: the buffer into which the data is read.

Returns
int the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.

Throws
IOException if an I/O error occurs.

skip

Added in API level 1
public long skip (long n)

Skips n bytes of input from the bytes that can be read from this input stream without blocking.

Fewer bytes than requested might be skipped. The actual number of bytes skipped is equal to n or the result of a call to available, whichever is smaller. If n is less than zero, no bytes are skipped.

The actual number of bytes skipped is returned.

Parameters
n long: the number of bytes to be skipped.

Returns
long the actual number of bytes skipped.

Throws
IOException if an I/O error occurs.