ccs.crypt
Class CipherInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          ccs.crypt.CipherInputStream

All Implemented Interfaces:

java.io.Closeable

Direct Known Subclasses:

AbstractBlockCipherInputStream

public abstract class CipherInputStream
extends java.io.FilterInputStream

The base class for input streams returned by Cipher subclasses. A CipherInputStream reads an underlying stream of Ciphertext and provides plaintext.

Field Summary

protected boolean	isDelimit Whether this stream is self-delimiting.
protected byte[]	temp8 An 8-byte scratch space.

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

protected

CipherInputStream(java.io.InputStream is, boolean isDelimit) Creates a new CipherInputStream based on the supplied underlying stream.

Method Summary

int	available() Returns the number of bytes that can be read from the underlying input stream without blocking.
void	close() Finishes with this decryption, releases the decryption engine and closes the underlying stream.
abstract void	finish() Finishes with this decryption and releases the decryption engine, but does not close the underlying stream.
void	mark(int readlimit) Does nothing: mark / reset is not supported.
boolean	markSupported() Indicates whether this input stream supports the mark and reset methods, which it does not.
int	read() Returns the next byte of plaintext as an int in the range 0 - 255, or -1 if the stream is exhausted.
int	read(byte[] b) Reads up to b.length bytes into b.
abstract int	read(byte[] b, int off, int len) Reads up to len bytes of plaintext into b[], starting at off.
void	reset() Does nothing: mark / reset is not supported.
long	skip(long n) Skips over and discards n bytes of data from this input stream.

Methods inherited from class java.lang.Object

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

Field Detail

temp8

protected byte[] temp8

An 8-byte scratch space. Useful for a) buffering single-byte reads; b) working with packed longs.

See Also:

Unsigned.writePacked(java.io.OutputStream, long, byte[])

isDelimit

protected boolean isDelimit

Whether this stream is self-delimiting.

Constructor Detail

CipherInputStream

protected CipherInputStream(java.io.InputStream is,
                            boolean isDelimit)

Creates a new CipherInputStream based on the supplied underlying stream. Use the getInputStream() method of a Cipher to obatain a CipherInputStream. NB. This ctor does not set the dam. Recommended strategy: on first read (set a flag to detect this) set the dam to the correct ciphertext length (if delimited), then write away.

Parameters:

is - The underlying (ciphertext) stream

Method Detail

read

public int read()
         throws java.io.IOException

Returns the next byte of plaintext as an int in the range 0 - 255, or -1 if the stream is exhausted. Blocks until the datum is made available.

Overrides:

read in class java.io.FilterInputStream

Returns:

The byte.

Throws:

java.io.IOException - if an error occurs.

read

public abstract int read(byte[] b,
                         int off,
                         int len)
                  throws java.io.IOException

Reads up to len bytes of plaintext into b[], starting at off. Blocks until some input is available.

Overrides:

read in class java.io.FilterInputStream

Parameters:

b - The buffer to read into. Cannot be null.

off - The starting offset.

len - The maximum number of bytes to read.

Returns:

the total number of byes read, or -1 if the stream is exhausted.

Throws:

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

read

public int read(byte[] b)
         throws java.io.IOException

Reads up to b.length bytes into b. Exactly equivalent to read(b, 0, b.length).

Overrides:

read in class java.io.FilterInputStream

Parameters:

b - The buffer to read into. Cannot be null.

Returns:

the total number of byes read, or -1 if the stream is exhausted.

Throws:

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

skip

public long skip(long n)
          throws java.io.IOException

Skips over and discards n bytes of data from this input stream. Unlike its superclass, this method is guaranteed to skip the number of bytes requested unless the stream comes up short.

Overrides:

skip in class java.io.FilterInputStream

Parameters:

n - The number of bytes to be skipped.

Returns:

The actual number of bytes skipped.

Throws:

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

available

public int available()
              throws java.io.IOException

Returns the number of bytes that can be read from the underlying input stream without blocking. This is generally not much of a guide to anything and shouldn't be relied upon.

Overrides:

available in class java.io.FilterInputStream

Returns:

The number of bytes that can be read from the underlying input stream without blocking, maybe. If you're lucky.

Throws:

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

finish

public abstract void finish()
                     throws java.io.IOException

Finishes with this decryption and releases the decryption engine, but does not close the underlying stream.

Throws:

java.io.IOException - if an error occurs.

close

public void close()
           throws java.io.IOException

Finishes with this decryption, releases the decryption engine and closes the underlying stream.

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.FilterInputStream

Throws:

java.io.IOException - if an error occurs.

mark

public void mark(int readlimit)

Does nothing: mark / reset is not supported.

Overrides:

mark in class java.io.FilterInputStream

Parameters:

readlimit - Ignored.

reset

public void reset()

Does nothing: mark / reset is not supported.

Overrides:

reset in class java.io.FilterInputStream

markSupported

public boolean markSupported()

Indicates whether this input stream supports the mark and reset methods, which it does not.

Overrides:

markSupported in class java.io.FilterInputStream

Returns:

false - mark/reset isn't supported.