org.bouncycastle.crypto.io

Class CipherInputStream

java.lang.Object

java.io.InputStream

com.joshvm.java.io.FilterInputStream

org.bouncycastle.crypto.io.CipherInputStream

public class CipherInputStream
extends com.joshvm.java.io.FilterInputStream

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.

Field Summary

Fields inherited from class com.joshvm.java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor and Description
CipherInputStream(InputStream is, AEADBlockCipher cipher) Constructs a CipherInputStream from an InputStream and an AEADBlockCipher.
CipherInputStream(InputStream is, AEADBlockCipher cipher, int bufSize) Constructs a CipherInputStream from an InputStream, an AEADBlockCipher, and a specified internal buffer size.
CipherInputStream(InputStream is, BufferedBlockCipher cipher) Constructs a CipherInputStream from an InputStream and a BufferedBlockCipher.
CipherInputStream(InputStream is, BufferedBlockCipher cipher, int bufSize) Constructs a CipherInputStream from an InputStream, a BufferedBlockCipher, and a specified internal buffer size.
CipherInputStream(InputStream is, StreamCipher cipher) Constructs a CipherInputStream from an InputStream and a StreamCipher.
CipherInputStream(InputStream is, StreamCipher cipher, int bufSize) Constructs a CipherInputStream from an InputStream, a StreamCipher, and a specified internal buffer size.

Method Summary

Methods

Modifier and Type	Method and Description
int	available() Returns 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 the underlying input stream and finalises the processing of the data by the cipher.
void	mark(int readlimit) Mark the current position.
boolean	markSupported() Return true if mark(readlimit) is supported.
int	read() Reads data from the underlying stream and processes it with the cipher until the cipher outputs data, and returns the next available byte.
int	read(byte[] b) Reads data from the underlying stream and processes it with the cipher until the cipher outputs data, and then returns up to b.length bytes in the provided array.
int	read(byte[] b, int off, int len) Reads data from the underlying stream and processes it with the cipher until the cipher outputs data, and then returns up to len bytes in the provided array.
void	reset() Reset to the last marked position, if supported.
long	skip(long n) Skips over and discards n bytes of data from this input stream.

Methods inherited from class java.lang.Object

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

Constructor Detail

CipherInputStream

public CipherInputStream(InputStream is,
                 BufferedBlockCipher cipher)

Constructs a CipherInputStream from an InputStream and a BufferedBlockCipher.

CipherInputStream

public CipherInputStream(InputStream is,
                 StreamCipher cipher)

Constructs a CipherInputStream from an InputStream and a StreamCipher.

CipherInputStream

public CipherInputStream(InputStream is,
                 AEADBlockCipher cipher)

Constructs a CipherInputStream from an InputStream and an AEADBlockCipher.

CipherInputStream

public CipherInputStream(InputStream is,
                 BufferedBlockCipher cipher,
                 int bufSize)

Constructs a CipherInputStream from an InputStream, a BufferedBlockCipher, and a specified internal buffer size.

CipherInputStream

public CipherInputStream(InputStream is,
                 StreamCipher cipher,
                 int bufSize)

Constructs a CipherInputStream from an InputStream, a StreamCipher, and a specified internal buffer size.

CipherInputStream

public CipherInputStream(InputStream is,
                 AEADBlockCipher cipher,
                 int bufSize)

Constructs a CipherInputStream from an InputStream, an AEADBlockCipher, and a specified internal buffer size.

Method Detail

read

public int read()
         throws IOException

Reads data from the underlying stream and processes it with the cipher until the cipher outputs data, and returns the next available byte.

If the underlying stream is exhausted by this call, the cipher will be finalised.

Overrides:

read in class com.joshvm.java.io.FilterInputStream

Returns:

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

Throws:

IOException - if there was an error closing the input stream.

InvalidCipherTextIOException - if the data read from the stream was invalid ciphertext (e.g. the cipher is an AEAD cipher and the ciphertext tag check fails).

read

public int read(byte[] b)
         throws IOException

Reads data from the underlying stream and processes it with the cipher until the cipher outputs data, and then returns up to b.length bytes in the provided array.

If the underlying stream is exhausted by this call, the cipher will be finalised.

Overrides:

read in class com.joshvm.java.io.FilterInputStream

Parameters:

b - the buffer into which the data is read.

Returns:

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 there was an error closing the input stream.

InvalidCipherTextIOException - if the data read from the stream was invalid ciphertext (e.g. the cipher is an AEAD cipher and the ciphertext tag check fails).

See Also:

InputStream.read(byte[], int, int)

read

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

Reads data from the underlying stream and processes it with the cipher until the cipher outputs data, and then returns up to len bytes in the provided array.

If the underlying stream is exhausted by this call, the cipher will be finalised.

Overrides:

read in class com.joshvm.java.io.FilterInputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in the destination array b

len - the maximum number of bytes read.

Returns:

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 there was an error closing the input stream.

InvalidCipherTextIOException - if the data read from the stream was invalid ciphertext (e.g. the cipher is an AEAD cipher and the ciphertext tag check fails).

See Also:

InputStream.read()

skip

public long skip(long n)
          throws IOException

Description copied from class: InputStream

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

The skip method of InputStream creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method.

Overrides:

skip in class com.joshvm.java.io.FilterInputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs.

available

public int available()
              throws IOException

Description copied from class: InputStream

Returns 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. The next caller might be the same thread or another thread.

The available method for class InputStream always returns 0.

This method should be overridden by subclasses.

Overrides:

available in class com.joshvm.java.io.FilterInputStream

Returns:

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

Throws:

IOException - if an I/O error occurs.

close

public void close()
           throws IOException

Closes the underlying input stream and finalises the processing of the data by the cipher.

Overrides:

close in class com.joshvm.java.io.FilterInputStream

Throws:

IOException - if there was an error closing the input stream.

InvalidCipherTextIOException - if the data read from the stream was invalid ciphertext (e.g. the cipher is an AEAD cipher and the ciphertext tag check fails).

mark

public void mark(int readlimit)

Mark the current position.

This method only works if markSupported() returns true - which means the underlying stream supports marking, and the cipher passed in to this stream's constructor is a SkippingCipher (so capable of being reset to an arbitrary point easily).

Overrides:

mark in class com.joshvm.java.io.FilterInputStream

Parameters:

readlimit - the maximum read ahead required before a reset() may be called.

See Also:

InputStream.reset()

reset

public void reset()
           throws IOException

Reset to the last marked position, if supported.

Overrides:

reset in class com.joshvm.java.io.FilterInputStream

Throws:

IOException - if marking not supported by the cipher used, or the underlying stream.

See Also:

InputStream.mark(int), IOException

markSupported

public boolean markSupported()

Return true if mark(readlimit) is supported. This will be true if the underlying stream supports marking and the cipher used is a SkippingCipher,

Overrides:

markSupported in class com.joshvm.java.io.FilterInputStream

Returns:

true if mark(readlimit) supported, false otherwise.

See Also:

InputStream.mark(int), InputStream.reset()