de.schlichtherle.crypto.io.raes
Class Type0RaesReadOnlyFile

java.lang.Object
  de.schlichtherle.io.rof.AbstractReadOnlyFile
      de.schlichtherle.io.rof.FilterReadOnlyFile
          de.schlichtherle.crypto.io.CipherReadOnlyFile
              de.schlichtherle.crypto.io.raes.RaesReadOnlyFile
                  de.schlichtherle.crypto.io.raes.Type0RaesReadOnlyFile

All Implemented Interfaces:

ReadOnlyFile

 class Type0RaesReadOnlyFile
extends RaesReadOnlyFile

Reads a type 0 RAES file.

Since:

TrueZIP 6.0

Version:

$Id: Type0RaesReadOnlyFile.java 06f3ba684701 2010/11/04 01:15:55 christian $

Author:

Christian Schlichtherle

Field Summary

private byte[]	footer The footer of the data envelope containing the authentication codes.
private int	keyStrength The key strength.
private CipherParameters	macParam The parameters required to init the Message Authentication Code (MAC).
private static long	MIN_KEY_RETRY_DELAY The minimum delay between subsequent attempts to authenticate a key in milliseconds.

Fields inherited from class de.schlichtherle.io.rof.FilterReadOnlyFile

rof

Constructor Summary

Type0RaesReadOnlyFile(ReadOnlyFile rof, Type0RaesParameters parameters)

Method Summary

void	authenticate() Authenticates all encrypted data in the read only file.
private static long	enforceSuspensionPenalty(long last)
int	getKeySizeBits() Returns the key size in bits which is actually used to decrypt the data of this RAES file.

Methods inherited from class de.schlichtherle.crypto.io.raes.RaesReadOnlyFile

getInstance, getInstance, readUByte, readUInt, readUShort

Methods inherited from class de.schlichtherle.crypto.io.CipherReadOnlyFile

close, computeMac, getFilePointer, init, length, read, read, seek

Methods inherited from class de.schlichtherle.io.rof.AbstractReadOnlyFile

read, readFully, readFully, skipBytes

Methods inherited from class java.lang.Object

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

Field Detail

MIN_KEY_RETRY_DELAY

private static final long MIN_KEY_RETRY_DELAY

The minimum delay between subsequent attempts to authenticate a key in milliseconds.

See Also:

Constant Field Values

keyStrength

private final int keyStrength

The key strength.

macParam

private final CipherParameters macParam

The parameters required to init the Message Authentication Code (MAC).

footer

private final byte[] footer

The footer of the data envelope containing the authentication codes.

Constructor Detail

Type0RaesReadOnlyFile

Type0RaesReadOnlyFile(ReadOnlyFile rof,
                      Type0RaesParameters parameters)
                throws NullPointerException,
                       FileNotFoundException,
                       RaesException,
                       RaesKeyException,
                       IOException

Throws:

NullPointerException

FileNotFoundException

RaesException

RaesKeyException

IOException

Method Detail

enforceSuspensionPenalty

private static long enforceSuspensionPenalty(long last)

getKeySizeBits

public int getKeySizeBits()

Description copied from class: RaesReadOnlyFile

Returns the key size in bits which is actually used to decrypt the data of this RAES file.

Specified by:

getKeySizeBits in class RaesReadOnlyFile

authenticate

public void authenticate()
                  throws RaesAuthenticationException,
                         IOException

Description copied from class: RaesReadOnlyFile

Authenticates all encrypted data in the read only file. It is safe to call this method multiple times to detect if the file has been tampered with meanwhile.

This is the second, optional step of authentication. The first, mandatory step is to computeMac the cipher key and cipher text length only and has already been successfully completed in the constructor.

Specified by:

authenticate in class RaesReadOnlyFile

Throws:

RaesAuthenticationException - If the computed MAC does not match the MAC declared in the RAES file.

IOException - On any I/O related issue.