March 25, 2009

High level languages (don't) byte

My primary development language is Java, which is a pretty good high level language, in that it offers lots of useful features and expansive libraries even if it does take some of the finer control out of your hands.  It's even got some very handy libraries for arbitrarily-large integer and floating point math (i.e. BigInteger and BigDecimal).  All of that put together makes it a pretty handy language for doing math type stuff.

... or so you'd think.  Java lacks one crucial element for doing serious math/crypto work directly: the unsigned byte.  The thing java calls a byte contains signed values in the range from -128 to 127.  This is an amazingly frustrating thing to discover in the midst of attempting to implement any algorithm that requires real bit twiddling.  You can still do it, but you constantly have to work around the fact that you're working with a signed byte, and the fact that Java will refuse to assign it a value like 0xff.  The frustrating thing is that it wouldn't have been hard to add an unsigned byte to Java as a primitive type, but for some reason the Sun guys thought they could do without.  I managed do implement RSA in Java well enough, but I tired rather quickly of trying to do AES with it, and ended up going to MatLab.

Yeah, I know, copout on my part.  It was a class assignment, though, and the language chosen didn't matter, only that the steps were illustrated, and finding MatLab code for AES was trivial.  Next time, though, I'm ready.

public class Constants
{
    public static final byte    X_FF                  = -1;
    public static final byte    X_FE                  = -2;
    public static final byte    X_FD                  = -3;
    public static final byte    X_FC                  = -4;
    public static final byte    X_FB                  = -5;
    public static final byte    X_FA                  = -6;
    public static final byte    X_F9                  = -7;
    public static final byte    X_F8                  = -8;
    public static final byte    X_F7                  = -9;
    public static final byte    X_F6                  = -10;
    public static final byte    X_F5                  = -11;
    public static final byte    X_F4                  = -12;
    public static final byte    X_F3                  = -13;
    public static final byte    X_F2                  = -14;
    public static final byte    X_F1                  = -15;
    public static final byte    X_F0                  = -16;

    public static final byte    X_EF                  = -17;
    public static final byte    X_EE                  = -18;
    public static final byte    X_ED                  = -19;
    public static final byte    X_EC                  = -20;
    public static final byte    X_EB                  = -21;
    public static final byte    X_EA                  = -22;
    public static final byte    X_E9                  = -23;
    public static final byte    X_E8                  = -24;
    public static final byte    X_E7                  = -25;
    public static final byte    X_E6                  = -26;
    public static final byte    X_E5                  = -27;
    public static final byte    X_E4                  = -28;
    public static final byte    X_E3                  = -29;
    public static final byte    X_E2                  = -30;
    public static final byte    X_E1                  = -31;
    public static final byte    X_E0                  = -32;

    public static final byte    X_DF                  = -33;
    public static final byte    X_DE                  = -34;
    public static final byte    X_DD                  = -35;
    public static final byte    X_DC                  = -36;
    public static final byte    X_DB                  = -37;
    public static final byte    X_DA                  = -38;
    public static final byte    X_D9                  = -39;
    public static final byte    X_D8                  = -40;
    public static final byte    X_D7                  = -41;
    public static final byte    X_D6                  = -42;
    public static final byte    X_D5                  = -43;
    public static final byte    X_D4                  = -44;
    public static final byte    X_D3                  = -45;
    public static final byte    X_D2                  = -46;
    public static final byte    X_D1                  = -47;
    public static final byte    X_D0                  = -48;

    public static final byte    X_CF                  = -49;
    public static final byte    X_CE                  = -50;
    public static final byte    X_CD                  = -51;
    public static final byte    X_CC                  = -52;
    public static final byte    X_CB                  = -53;
    public static final byte    X_CA                  = -54;
    public static final byte    X_C9                  = -55;
    public static final byte    X_C8                  = -56;
    public static final byte    X_C7                  = -57;
    public static final byte    X_C6                  = -58;
    public static final byte    X_C5                  = -59;
    public static final byte    X_C4                  = -60;
    public static final byte    X_C3                  = -61;
    public static final byte    X_C2                  = -62;
    public static final byte    X_C1                  = -63;
    public static final byte    X_C0                  = -64;

    public static final byte    X_BF                  = -65;
    public static final byte    X_BE                  = -66;
    public static final byte    X_BD                  = -67;
    public static final byte    X_BC                  = -68;
    public static final byte    X_BB                  = -69;
    public static final byte    X_BA                  = -70;
    public static final byte    X_B9                  = -71;
    public static final byte    X_B8                  = -72;
    public static final byte    X_B7                  = -73;
    public static final byte    X_B6                  = -74;
    public static final byte    X_B5                  = -75;
    public static final byte    X_B4                  = -76;
    public static final byte    X_B3                  = -77;
    public static final byte    X_B2                  = -78;
    public static final byte    X_B1                  = -79;
    public static final byte    X_B0                  = -80;

    public static final byte    X_AF                  = -81;
    public static final byte    X_AE                  = -82;
    public static final byte    X_AD                  = -83;
    public static final byte    X_AC                  = -84;
    public static final byte    X_AB                  = -85;
    public static final byte    X_AA                  = -86;
    public static final byte    X_A9                  = -87;
    public static final byte    X_A8                  = -88;
    public static final byte    X_A7                  = -89;
    public static final byte    X_A6                  = -90;
    public static final byte    X_A5                  = -91;
    public static final byte    X_A4                  = -92;
    public static final byte    X_A3                  = -93;
    public static final byte    X_A2                  = -94;
    public static final byte    X_A1                  = -95;
    public static final byte    X_A0                  = -96;

    public static final byte    X_9F                  = -97;
    public static final byte    X_9E                  = -98;
    public static final byte    X_9D                  = -99;
    public static final byte    X_9C                  = -100;
    public static final byte    X_9B                  = -101;
    public static final byte    X_9A                  = -102;
    public static final byte    X_99                  = -103;
    public static final byte    X_98                  = -104;
    public static final byte    X_97                  = -105;
    public static final byte    X_96                  = -106;
    public static final byte    X_95                  = -107;
    public static final byte    X_94                  = -108;
    public static final byte    X_93                  = -109;
    public static final byte    X_92                  = -110;
    public static final byte    X_91                  = -111;
    public static final byte    X_90                  = -112;

    public static final byte    X_8F                  = -113;
    public static final byte    X_8E                  = -114;
    public static final byte    X_8D                  = -115;
    public static final byte    X_8C                  = -116;
    public static final byte    X_8B                  = -117;
    public static final byte    X_8A                  = -118;
    public static final byte    X_89                  = -119;
    public static final byte    X_88                  = -120;
    public static final byte    X_87                  = -121;
    public static final byte    X_86                  = -122;
    public static final byte    X_85                  = -123;
    public static final byte    X_84                  = -124;
    public static final byte    X_83                  = -125;
    public static final byte    X_82                  = -126;
    public static final byte    X_81                  = -127;
    public static final byte    X_80                  = -128;
    
}

package com.yourdomain;

import com.yourdomain.utils.Constants;

public class HexByte
extends Constants
{   
    private byte[] byteArray = new byte[] { X_FF, X_DE };
    
    public static void main(String[] args)
    {
    }
}

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