ccs.crypt
Class AbstractBlockCipherInputStream

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

All Implemented Interfaces:

java.io.Closeable

Direct Known Subclasses:

BCCHInputStream

public abstract class AbstractBlockCipherInputStream
extends CipherInputStream

A Block-cipher input stream. This handles the housekeeping, and delegates all actual crypto to subclasses.

Field Summary

Fields inherited from class ccs.crypt.CipherInputStream

isDelimit, temp8

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

protected

AbstractBlockCipherInputStream(DammedInputStream is, boolean isDelimit, AbstractBlockCipher cipher)

Method Summary

void	finish() Finishes with this decryption and releases the decryption engine, but does not close the underlying stream.
int	read(byte[] b, int off, int len) Reads up to len bytes of plaintext into b[], starting at off.
protected abstract void	readHeader(java.io.InputStream is) Read in the header, not including any self-delimiting information.

Methods inherited from class ccs.crypt.CipherInputStream

available, close, mark, markSupported, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractBlockCipherInputStream

protected AbstractBlockCipherInputStream(DammedInputStream is,
                                         boolean isDelimit,
                                         AbstractBlockCipher cipher)

Method Detail

finish

public void finish()
            throws java.io.IOException

Description copied from class: CipherInputStream

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

Specified by:

finish in class CipherInputStream

Throws:

java.io.IOException - if an error occurs.

read

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

Description copied from class: CipherInputStream

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

Specified by:

read in class CipherInputStream

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.

readHeader

protected abstract void readHeader(java.io.InputStream is)
                            throws java.io.IOException

Read in the header, not including any self-delimiting information. Typically this is just the IV (if in CBC mode). Unsigned.readFully is your friend. Remember to wash this through your MAC. The AbstractBlockCipher's buffer is available as scratch space.

Parameters:

is - The stream to read from.

Throws:

java.io.IOException