Thread: 2d (4x4) array insdie a 1d array. (Block cipher)

Hi guys

I am trying to create my block cipher as part of a uni project and what the block cipher consists of is putting in the characters in blocks of 4x4 arrays and to map it it has a look up. What i think i needto create is a 2d array inside each cell of a 1d array. Please see photo



Thats what i am tryiring to create ^^ . Has anyone got any suggestions of how i can do this. I eventually need to be able to subsititue different cells from differnet 4x4 arrays

I can get that code to work im taking it a step at a time.

What i have is i divde the number of chareacters by 16 to give a double number how ever i need to figure out how to make the double always round up to its whole number ( 12.4 > 13, 3.3 >4, 5.9>6). This will allow me to know how many 4x4 blocks to create then i can use the reference for loop to point to the stating coloum of each 4x4 block.. How can i round the double up ?

im a little confussed on how id implement it


i want somethinbg like


WHILE text is NOT EVENLY DIVDED BY 16
{
plaintext +=d 'a'
}
if text is evenly divded by 16
{
array [4][blockammount*4]
}

so the while loop will keep adding the letter a to the text string until it divides evenly if it does divide eaisly time that number by 4 to give the number of coloums needed in the array

i have never used mod before so i am a little stuck

In Java, a multidimensional array is nothing but an array of arrays. So, a char[] is an array where each element holds a char, char[][] is an array where each element is a char[] and char[][][] is an array of char[][].

For your requirement, you need to declare the array as

char[][][] myArray = new char[3][4][4];

Now each of the three elements of myArray is a two dimensional char array of size 4 X 4 -- a char[4][4]

db

Originally Posted by Darryl.Burke

In Java, a multidimensional array is nothing but an array of arrays. So, a char[] is an array where each element holds a char, char[][] is an array where each element is a char[] and char[][][] is an array of char[][].

For your requirement, you need to declare the array as

char[][][] myArray = new char[3][4][4];

Now each of the three elements of myArray is a two dimensional char array of size 4 X 4 -- a char[4][4]

db

right at the moment i have

int w=0;
  while(w !=hexarray.length)
  {
        for(int x=0; x< BlockArray.length; x++)
        {
            for(int y=0;y<4;y++)
            {
                for(int z=0;z<4;z++)
                {
 
               System.out.print( BlockArray[x][y][z] = hexarray[w]);
 
                }
 
            }
 
        }
    w++;
   }

im also tying to fill;e each block coloum by coloum as shown in my pic..

am I on the right lines to achive this ?

im pretty sure that the 3d array isnt what im after ive never used 3d arrays before im thinking it like a cube am i right ?

it needs to be one big array because i need to substitutae a cell in 1 4x4 block with another one in a different 4x4 array

I have just took a manual aproach to print out what comes in each block i was trying to put a print statement in the loop but this seems to work
code:

        for(int x=0; x< BlockArray.length; x++)
        {
            for(int y=0;y<4;y++)
            {
                for(int z=0;z<4;z++)
                {
 
               BlockArray[x][z] [y] = hexarray[w++];
 
                }
 
            }
 
        }
 
            System.out.println("Length: "+hexarray.length+" Hash array: ");
 
            for(int d=0;d<hexarray.length;d++)
            {
               System.out.print(hexarray[d]+" ");
            }
 
            System.out.println("\nBlock 1: \n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[0][0][0], BlockArray[0][0][1],BlockArray[0][0][2],BlockArray[0][0][3]+"\n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[0][1][0], BlockArray[0][1][1],BlockArray[0][1][2],BlockArray[0][1][3]+"\n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[0][2][0], BlockArray[0][2][1],BlockArray[0][2][2],BlockArray[0][2][3]+"\n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[0][3][0], BlockArray[0][3][1],BlockArray[0][3][2],BlockArray[0][3][3]+"\n");
 
            System.out.println("Block 2: \n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[1][0][0], BlockArray[1][0][1],BlockArray[1][0][2],BlockArray[1][0][3]+"\n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[1][1][0], BlockArray[1][1][1],BlockArray[1][1][2],BlockArray[1][1][3]+"\n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[1][2][0], BlockArray[1][2][1],BlockArray[1][2][2],BlockArray[1][2][3]+"\n");
            System.out.printf("%4s %4s %4s %4s", BlockArray[1][3][0], BlockArray[1][3][1],BlockArray[1][3][2],BlockArray[1][3][3]+"\n");

Output:

Length: 32 Hash array: 
41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f 50 51 30 31 32 33 34 35 36 37 38 39 30 31 32 33 34 
Block 1: 
 
  41   45   49  4d
  42   46   4a  4e
  43   47   4b  4f
  44   48   4c  50
Block 2: 
 
  51   33   37  31
  30   34   38  32
  31   35   39  33
  32   36   30  34
 Lenghth of block array 2
string length: 32

brilliant i got it working thanks for your help