com.fasteasytrade.JRandTest.Algo
Class ZAC3

java.lang.Object
  com.fasteasytrade.JRandTest.Algo.Cipher
      com.fasteasytrade.JRandTest.Algo.ZAC3

public class ZAC3

extends Cipher

ZAC3 encryption algorithm Copyright (c) 2005 Zur Aougav

Symetric algorithm.

Use 3 ARC4 keys:

• cryptKey to encrypt input bytes,
• fillKey to add bytes to output,
• controlKey to control swapping between each two bytes - ciphered byte and fill byte.

Hence, ciphered text length is double input's length.

Before encryption starts, each key is skipped a random number of times (with 4096 <= skip <= 69631). SHA1 digest message (20 bytes) is calculated from the invisible key output. The 20 bytes should be written at the header of the ciphered message/file. Of course, decryption does the reverse, read the hash 20 bytes, and step each key with a check if digest message arrived at is the correct one. Hence, the random number of steps is never exposed directly, but the hash contains implicitly the correct position.

Author:

Zur Aougav

Field Summary

(package private) byte[]	controlBuf Original key bytes buffer for controlKey
(package private) RC4Key	controlKey controlKey gives one byte to enable swap of encrypt data and fill data (from fillKey)
(package private) byte[]	controlShaDigest controlKey is processed controlSkip times, and prng data is hashed using sha1.
(package private) int	controlSkip random number we skip controlKey before start using it.
(package private) byte[]	cryptBuf Original key bytes buffer for cryptKey
(package private) RC4Key	cryptKey encrypt and decrypt data using cryptKey
(package private) byte[]	cryptShaDigest cryptKey is processed cryptSkip times, and prng data is hashed using sha1.
(package private) int	cryptSkip random number we skip cryptKey before start using it.
(package private) byte[]	fillBuf Original key bytes buffer for fillKey
(package private) RC4Key	fillKey add one byte for each encrypt data byte
(package private) byte[]	fillShaDigest fillKey is processed fillSkip times, and prng data is hashed using sha1.
(package private) int	fillSkip random number we skip fillKey before start using it.
(package private) boolean	garbage Boolean flag if we ever find an incorrect fill byte in data.
(package private) Random	rnd Use java random class to fill new keys put some garbage bytes in output buffer (if decryption fails).

Constructor Summary

ZAC3()
default constructor - does nothing.

ZAC3(byte[] cryptBuf, byte[] fillBuf, byte[] controlBuf)
constructor with 3 keys to setup.

Method Summary

boolean	decrypt(byte[] inputBuf, byte[] outputBuf, int len) decrypt buffer.
boolean	encrypt(byte[] inputBuf, byte[] outputBuf) encrypt buffer. each input byte becomes two bytes, by adding one byte from fillKey.
protected void	finalize() carefull clear of buffers in ZAC3 object
byte[]	getControlBuf()
byte[]	getControlShaDigest()
byte[]	getCryptBuf()
byte[]	getCryptShaDigest()
byte[]	getFillBuf()
byte[]	getFillShaDigest()
boolean	initDecrypt(byte[] cryptShaDigest, byte[] fillShaDigest, byte[] controlShaDigest) init keys, using hash on prng of each key.
void	initEncrypt() init keys, using hash on prng of each key.
static void	main(String[] args) Run ZAC3 Algorithm.
void	reset() Reset "state" of prng by setting keys to bufkeys and skip each key.
void	setup(byte[] cryptBuf, byte[] fillBuf, byte[] controlBuf) setup 3 keys to ZAC3 algorithm.

Methods inherited from class com.fasteasytrade.JRandTest.Algo.Cipher

compareBytes

Methods inherited from class java.lang.Object

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

Field Detail

cryptKey

RC4Key cryptKey

encrypt and decrypt data using cryptKey

fillKey

RC4Key fillKey

add one byte for each encrypt data byte

controlKey

RC4Key controlKey

controlKey gives one byte to enable swap of encrypt data and fill data (from fillKey)

cryptShaDigest

byte[] cryptShaDigest

cryptKey is processed cryptSkip times, and prng data is hashed using sha1. Digest "message" is kept in cryptShaDigest.

fillShaDigest

byte[] fillShaDigest

fillKey is processed fillSkip times, and prng data is hashed using sha1. Digest "message" is kept in fillShaDigest.

controlShaDigest

byte[] controlShaDigest

controlKey is processed controlSkip times, and prng data is hashed using sha1. Digest "message" is kept in controlShaDigest.

cryptBuf

byte[] cryptBuf

Original key bytes buffer for cryptKey

fillBuf

byte[] fillBuf

Original key bytes buffer for fillKey

controlBuf

byte[] controlBuf

Original key bytes buffer for controlKey

cryptSkip

int cryptSkip

random number we skip cryptKey before start using it.

fillSkip

int fillSkip

random number we skip fillKey before start using it.

controlSkip

int controlSkip

random number we skip controlKey before start using it.

garbage

boolean garbage

Boolean flag if we ever find an incorrect fill byte in data.

Only used while decryption.

If true, we fill (silently) all output data with random data from rnd variable.

rnd

Random rnd

Use java random class to

1. fill new keys
2. put some garbage bytes in output buffer (if decryption fails).

Constructor Detail

ZAC3

public ZAC3()

default constructor - does nothing.

ZAC3

public ZAC3(byte[] cryptBuf,
            byte[] fillBuf,
            byte[] controlBuf)

constructor with 3 keys to setup.

Parameters:

cryptBuf - kept in obejct cryptBuf and init cryptKey

fillBuf - kept in obejct fillBuf and init fillKey

controlBuf - kept in obejct controlBuf and init controlKey

Method Detail

setup

public void setup(byte[] cryptBuf,
                  byte[] fillBuf,
                  byte[] controlBuf)

setup 3 keys to ZAC3 algorithm. If one of the input buffers is null, we fill it with 256 random bytes.

keep keys and skip data in object so initEncrypt() and reset() can run properly.

Parameters:

cryptBuf - 256 bytes to cryptKey

fillBuf - 256 bytes to fillKey

controlBuf - 256 bytes to controlKey

initEncrypt

public void initEncrypt()

init keys, using hash on prng of each key. Digest message generated from key xyz is kept as xyzShaDigest variable.

initEncrypt method is run before encryption starts.

encrypt

public boolean encrypt(byte[] inputBuf,
                       byte[] outputBuf)

encrypt buffer. each input byte becomes two bytes, by adding one byte from fillKey. The byte from controlKey is controlling the order of the two result bytes:

if control_byte is even
then output order is concat(encrypted_data_byte, fill_byte),
else output order is concat(fill_byte, encrypted_data_byte)

caller gets back a clear input buffer (full of 0x00).

Parameters:

inputBuf - input bytes buffer, length n

outputBuf - output encrypted bytes buffer, must be length 2n

Returns:

returns FALSE if inputs are null or lengths are not correct. Else, encrypt data and returns TRUE.

initDecrypt

public boolean initDecrypt(byte[] cryptShaDigest,
                           byte[] fillShaDigest,
                           byte[] controlShaDigest)

init keys, using hash on prng of each key. Digest message generated from key xyz is compared with xyzShaDigest variable.

initDecrypt method is run before decryption starts.

Returns:

true if all skip counters are found, and state is ready to decrypt cipher data. Else, false.

decrypt

public boolean decrypt(byte[] inputBuf,
                       byte[] outputBuf,
                       int len)

decrypt buffer. Two input bytes become one byte. Determin where is the ciphred data and the fill byte using rhe control byte.

if control_byte is even
then input order is concat(encrypted_data_byte, fill_byte),
else input order is concat(fill_byte, encrypted_data_byte)

If filler byte is not in a correct place, we flag garbage boolean value, and hence forth, fill *any* output buffer with random data without decryption. Note taht no alert is given.

Parameters:

inputBuf - input ciphered bytes buffer, length 2n

outputBuf - output data bytes buffer, must be length n

len - intput buffer length

Returns:

returns FALSE if inputs are null or lengths are not correct. Else, encrypt data and returns TRUE.

reset

public void reset()

Reset "state" of prng by setting keys to bufkeys and skip each key.

getControlShaDigest

public byte[] getControlShaDigest()

Returns:

Returns the controlShaDigest.

getCryptShaDigest

public byte[] getCryptShaDigest()

Returns:

Returns the cryptShaDigest.

getFillShaDigest

public byte[] getFillShaDigest()

Returns:

Returns the fillShaDigest.

getControlBuf

public byte[] getControlBuf()

Returns:

Returns the controlBuf.

getCryptBuf

public byte[] getCryptBuf()

Returns:

Returns the cryptBuf.

getFillBuf

public byte[] getFillBuf()

Returns:

Returns the fillBuf.

finalize

protected void finalize()
                 throws Throwable

carefull clear of buffers in ZAC3 object

Throws:

Throwable

main

public static void main(String[] args)
                 throws Exception

Run ZAC3 Algorithm. Copyright (c) 2005 Zur Aougav

Command line syntax:

java ZAC3 [options] [ops] [inputfilename outputfilename]

options:
-crf <cryptKeyFile.key> default: cryptKeyFile.key
-fif <fillKeyFile.key> default: fillKeyFile.key
-cof <controlKeyFile.key> default: controlKeyFile.key

ops:
-h print this help message
-e encrypt inputfilename into outputfilename
-enc encrypt inputfilename into outputfilename
-d decrypt inputfilename into outputfilename
-dec decrypt inputfilename into outputfilename
-compare compare two files - inputfilename and outputfilename
-gen generate random keys and write them to key files

Parameters:

args - keys, operations, input and output filenames

Throws:

Exception - missing operands or IOExceptions