public class

CipherInputStream

extends FilterInputStream

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

Class Overview

This class wraps an InputStream and a cipher so that read() methods return data that are read from the underlying InputStream and processed by the cipher.

The cipher must be initialized for the requested operation before being used by a CipherInputStream. For example, if a cipher initialized for decryption is used with a CipherInputStream, the CipherInputStream tries to read the data an decrypt them before returning.

Summary

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Inherited Fields

From class java.io.FilterInputStream

Public Constructors
	CipherInputStream(InputStream is, Cipher c) Creates a new `CipherInputStream` instance for an `InputStream` and a cipher.

Protected Constructors
	CipherInputStream(InputStream is) Creates a new `CipherInputStream` instance for an `InputStream` without a cipher.

Public Methods
int	available() Returns an estimated number of bytes that can be read or skipped without blocking for more input.
void	close() Closes this `CipherInputStream`, also closes the underlying input stream and call `doFinal` on the cipher object.
boolean	markSupported() Returns whether this input stream supports `mark` and `reset`, which it does not.
int	read(byte[] b) Reads the next `b.length` bytes from this input stream into buffer `b`.
int	read() Reads the next byte from this cipher input stream.
int	read(byte[] b, int off, int len) Reads the next `len` bytes from this input stream into buffer `b` starting at offset `off`.
long	skip(long n) Skips up to n bytes from this input stream.

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Inherited Methods

From class java.io.FilterInputStream

int	available() Returns an estimated number of bytes that can be read or skipped without blocking for more input.
void	close() Closes this stream.
synchronized void	mark(int readlimit) Sets a mark position in this stream.
boolean	markSupported() Indicates whether this stream supports `mark()` and `reset()`.
int	read(byte[] buffer) Reads bytes from this stream and stores them in the byte array `buffer`.
int	read() Reads a single byte from the filtered stream and returns it as an integer in the range from 0 to 255.
int	read(byte[] buffer, int offset, int count) Reads at most `count` bytes from this stream and stores them in the byte array `buffer` starting at `offset`.
synchronized void	reset() Resets this stream to the last marked location.
long	skip(long count) Skips `count` number of bytes in this stream.

From class java.io.InputStream

int	available() Returns an estimated number of bytes that can be read or skipped without blocking for more input.
void	close() Closes this stream.
void	mark(int readlimit) Sets a mark position in this InputStream.
boolean	markSupported() Indicates whether this stream supports the `mark()` and `reset()` methods.
int	read(byte[] b) Reads bytes from this stream and stores them in the byte array `b`.
abstract int	read() Reads a single byte from this stream and returns it as an integer in the range from 0 to 255.
int	read(byte[] b, int offset, int length) Reads at most `length` bytes from this stream and stores them in the byte array `b` starting at `offset`.
synchronized void	reset() Resets this stream to the last marked location.
long	skip(long byteCount) Skips at most `n` bytes in this stream.

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object o) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Called before the object's memory is reclaimed by the VM.
final Class<? extends Object>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.
final void	wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long millis) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.

From interface java.io.Closeable

Public Constructors

public CipherInputStream (InputStream is, Cipher c)

Since: API Level 1

Creates a new CipherInputStream instance for an InputStream and a cipher.

Warning: passing a null source creates an invalid CipherInputStream. All read operations on such a stream will fail.

Parameters

is	the input stream to read data from.
c	the cipher to process the data with.

Protected Constructors

protected CipherInputStream (InputStream is)

Since: API Level 1

Creates a new CipherInputStream instance for an InputStream without a cipher.

A NullCipher is created and used to process the data.

Parameters

is	the input stream to read data from.

Public Methods

public int available ()

Since: API Level 1

Returns an estimated number of bytes that can be read or skipped without blocking for more input.

Note that this method provides such a weak guarantee that it is not very useful in practice.

Firstly, the guarantee is "without blocking for more input" rather than "without blocking": a read may still block waiting for I/O to complete — the guarantee is merely that it won't have to wait indefinitely for data to be written. The result of this method should not be used as a license to do I/O on a thread that shouldn't be blocked.

Secondly, the result is a conservative estimate and may be significantly smaller than the actual number of bytes available. In particular, an implementation that always returns 0 would be correct. In general, callers should only use this method if they'd be satisfied with treating the result as a boolean yes or no answer to the question "is there definitely data ready?".

Thirdly, the fact that a given number of bytes is "available" does not guarantee that a read or skip will actually read or skip that many bytes: they may read or skip fewer.

It is particularly important to realize that you must not use this method to size a container and assume that you can read the entirety of the stream without needing to resize the container. Such callers should probably write everything they read to a ByteArrayOutputStream and convert that to a byte array. Alternatively, if you're reading from a file, length() returns the current length of the file (though assuming the file's length can't change may be incorrect, reading a file is inherently racy).

The default implementation of this method in InputStream always returns 0. Subclasses should override this method if they are able to indicate the number of bytes available.

Returns

the estimated number of bytes available

Throws

IOException

public void close ()

Since: API Level 1

Closes this CipherInputStream, also closes the underlying input stream and call doFinal on the cipher object.

Throws

IOException	if an error occurs.

public boolean markSupported ()

Since: API Level 1

Returns whether this input stream supports mark and reset, which it does not.

Returns

false, since this input stream does not support mark and reset.

public int read (byte[] b)

Since: API Level 1

Reads the next b.length bytes from this input stream into buffer b.

Parameters

b	the buffer to be filled with data.

Returns

the number of bytes filled into buffer b, or -1 if the end of the stream is reached.

Throws

IOException	if an error occurs.

public int read ()

Since: API Level 1

Reads the next byte from this cipher input stream.

Returns

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

Throws

IOException	if an error occurs.

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

Since: API Level 1

Reads the next len bytes from this input stream into buffer b starting at offset off.

if b is null, the next len bytes are read and discarded.

Parameters

b	the buffer to be filled with data.
off	the offset to start in the buffer.
len	the maximum number of bytes to read.

Returns

the number of bytes filled into buffer b, or -1 of the of the stream is reached.

Throws

IOException	if an error occurs.
NullPointerException	if the underlying input stream is `null`.

public long skip (long n)

Since: API Level 1

Skips up to n bytes from this input stream.

The number of bytes skipped depends on the result of a call to available. The smaller of n and the result are the number of bytes being skipped.

Parameters

n	the number of bytes that should be skipped.

Returns

the number of bytes actually skipped.

Throws

IOException	if an error occurs

Interfaces

Classes

Exceptions

CipherInputStream

Class Overview

Summary

Public Constructors

public CipherInputStream (InputStream is, Cipher c)

Parameters

Protected Constructors

protected CipherInputStream (InputStream is)

Parameters

Public Methods

public int available ()

Returns

Throws

public void close ()

Throws

public boolean markSupported ()

Returns

public int read (byte[] b)

Parameters

Returns

Throws

public int read ()

Returns

Throws

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

Parameters

Returns

Throws

public long skip (long n)

Parameters

Returns

Throws