Mifare Access Bits Tool

[gngulrajani]

Hello All,

I wrote this small program to help me calculate the access bits. The one thing I am unsure of is what the bits in the lower nibble of bytes (6-8) do.

I wrote the program quickly and i am sure it has bugs. You should not trust this quality of the access bits it produces!

If you find any bugs or what i should do with the lower nibble of the access bits , please let me know.


-best
-greg

/** written by greg gulrajani
*
* decodes/encodeds Mifare access bits
*
* All text / tables taken from the MF1 IC S50 Specification
* from: http://www.nxp.com/acrobat_download/other/identification/m001052.pdf
*
*/

public class AclTool
{
 
  
    public static final String[] sector_str_perm = { 
"Never\tKey A\tKey A\tNever\tKey A\tKey A    | TRAILER       :0",
"Never\tNever\tKey A\tKey A\tKey A\tKey A    | TRL(TRANSPORT):1",
"Never\tNever\tKey A\tNever\tKey A\tNever    | TRAILER       :2",
"Never\tKey B\tKyA|B\tKey B\tNever\tKey B    | TRAILER       :3",
"Never\tKey B\tKyA|B\tNever\tNever\tKey B    | TRAILER       :4",
"Never\tNever\tKyA|B\tKey B\tNever\tNever    | TRAILER       :5",
"Never\tNever\tKyA|B\tNever\tNever\tNever    | TRAILER       :6",
"Never\tNever\tKyA|B\tNever\tNever\tNever    | TRAILER       :7"
};

    public static final String[] data_str_perm = { 
"KyA|B\tKA|B1\tKA|B1\tKA|B1\tTransport Config|No KeyB Auth:0",
"KyA|B\tNever\tNever\tKyA|B\tValue Block     |No KeyB Auth:1",
"KyA|B\tNever\tNever\tNever\tRead/Write Blk  |No KeyB Auth:2",
"Key B\tKey B\tNever\tNever\tRead/Write Blk  |            :3",
"KyA|B\tKey B\tNever\tNever\tRead/Write Blk  |            :4",
"Key B\tNever\tNever\tNever\tRead/Write Blk  |            :5",
"KyA|B\tKey B\tKey B\tKyA|B\tValue Blk       |            :6",
"Never\tNever\tNever\tNever\tRead/Write Blk  |            :7",
};
 
    public static final short DATA_BLOCK_0 = 0;
    public static final short DATA_BLOCK_1 = 1;
    public static final short DATA_BLOCK_2 = 2;
    public static final short SECTOR_TRAILER = 3;

    static boolean[][] bitarray = new boolean[3][8];

    static byte[] blockperm = new byte[4];

    static String sargs = "java AclTool [decode|encode] [ff ff ff|0-7 0-7 0-7]\njava AclTool decode 78 77 88\njava AclTool encode 5 5 5 3 (where 5 5 5 are Blocks 0-3 and 3 is the Section Trailer";

    public static void main(String[] args)
    {
        if (args[0].equals("decode"))
        {
            if (args.length != 4)   
            {
                System.err.println(sargs);
                System.exit(-1);
            }

            byte[] a =  new byte[4];
 
            a[0] = (byte) Integer.parseInt(args[1],16);
            a[1] = (byte) Integer.parseInt(args[2],16);
            a[2] = (byte) Integer.parseInt(args[3],16);
            decodeACL(a);

        } else if (args[0].equals("encode")) {

            if (args.length != 5)   
            {
                System.err.println(sargs);
                System.exit(-1);
            }

            byte[] a =  new byte[4];

            a[0] = (byte) Integer.parseInt(args[1]);
            a[1] = (byte) Integer.parseInt(args[2]);
            a[2] = (byte) Integer.parseInt(args[3]);
            a[3] = (byte) Integer.parseInt(args[4]);
            createACL(a);

        } else {

            System.err.println(sargs);
            System.exit(0);
        }

    }


    public static void decodeACL(byte[] a)
    {
        for (int j = 0; j < 3;j++)
        {
            for (int i =0;i < 8;i++)
            {
                int bit = ( 0x1 & a[j]  ) ;
                bitarray[j][i] =  (bit != 0 );  
                a[j] = (byte) ( a[j] >> 1 ) ;  
            }
        }


        // now place them in our bits into our out of order arrays    
        blockperm[DATA_BLOCK_0] = bin2byte(bitarray[1][4],bitarray[0][4],bitarray[2][4] );
        blockperm[DATA_BLOCK_1] = bin2byte(bitarray[1][5],bitarray[0][5],bitarray[2][5] );
        blockperm[DATA_BLOCK_2] = bin2byte(bitarray[1][6],bitarray[0][6],bitarray[2][6] );
        blockperm[SECTOR_TRAILER] = bin2byte(bitarray[1][7],bitarray[0][7],bitarray[2][7] );


        System.out.println("      C1 C2 C3\tread\twrite\tincrement\tdec/xfer/restor\tApp");
        System.out.println("------------------------------------------------------------------------------");

        System.out.println("BLK 0:"+bin2str(bitarray[1][4],bitarray[0][4],bitarray[2][4] ) +"\t"+ data_str_perm[blockperm[DATA_BLOCK_0]] );

        System.out.println("BLK 1:"+bin2str(bitarray[1][5],bitarray[0][5],bitarray[2][5])+"\t"+data_str_perm[blockperm[DATA_BLOCK_1]]); 

        System.out.println("BLK 2:"+bin2str(bitarray[1][6],bitarray[0][6],bitarray[2][6])+"\t"+ data_str_perm[blockperm[DATA_BLOCK_2]]);
        System.out.println("");
        System.out.println("KEY A\t\tAccess Bits\t\tKEY B\t\t\tRem");
        System.out.println("read\twrite\tread\twrite\tread\twrite");
        System.out.println("------------------------------------------------------------------------------");
        System.out.println("STR 4:"+bin2str(bitarray[1][7],bitarray[0][7],bitarray[2][7] )+"\t"+ sector_str_perm[blockperm[SECTOR_TRAILER]]  )   ;



        System.out.println(" 8 7 6 5 4 3 2 1");
        for (int i = 0; i < 3;i++)
        {
            //for (int j = 0; j < 8;j++)
            for (int j = 7; j >=0 ;j--)
            {
                System.out.print(" "+(bitarray[i][j]==true?1:0));
            }
            System.out.println("");
        }
    }


    public static void createACL(byte a[])
    {
        boolean[][] c1c2c3 = new boolean[4][3];

        for (int j = 0; j < 4;j++)
        {
            for (int i =0;i < 3;i++)
            {
                int bit = ( 0x1 & a[j]  );
                c1c2c3[j][i] =  (bit != 0 );  
                a[j] = (byte) ( a[j] >> 1 ) ;  
            }

        }
 
        byte byte6 = bin2byte(c1c2c3[3][1],c1c2c3[2][1],c1c2c3[1][1],c1c2c3[0][1],false,false,false,false);
        byte byte7 = bin2byte(c1c2c3[3][0],c1c2c3[2][0],c1c2c3[1][0],c1c2c3[0][0],false,false,false,false);
        byte byte8 = bin2byte(c1c2c3[3][2],c1c2c3[2][2],c1c2c3[1][2],c1c2c3[0][2],false,false,false,false);

      System.out.println("output:".format("%x %x %x",byte6,byte7,byte8));
      System.out.println("done");

        byte[] ba = { byte6,byte7,byte8 };
        decodeACL(ba);
    }



    public static String bin2str(boolean C1,boolean C2,boolean C3)
    {
        return "".format("%s %s %s",(C3==true?1:0),(C2==true?1:0),(C1==true?1:0));
    }

    public static byte bin2byte(boolean C1,boolean C2,boolean C3)
    {
        byte dd =(byte) (C1==true?1:0) ;
        dd =(byte) (dd << 1);
        dd = (byte) (dd | (int) (C2==true?1:0) ) ;
        dd =(byte) (dd << 1);
        dd = (byte) (dd | (int) (C3==true?1:0) ) ;
        return dd;
    }

    public static byte bin2byte(boolean C1,boolean C2,boolean C3,boolean C4,boolean C5,boolean  C6, boolean C7 , boolean C8)
    {
        byte dd = bin2byte(C1,C2,C3);
        dd =(byte) (dd << 3);
        dd =(byte) (dd |  bin2byte(C4,C5,C6) ) ;
        dd =(byte) (dd << 1);
        dd = (byte) (dd | (int) (C7==true?1:0) ) ;
        dd =(byte) (dd << 1);
        dd = (byte) (dd | (int) (C8==true?1:0) ) ;
        return dd;
    }
}

[tdelazzari]

I am unsure of is what the bits in the lower nibble of bytes (6-8) do.

Concerning Sector Trailer Access Bits, it is coded on 4 Bytes but I don't know about Byte number 9... I assume this is a kind of "check byte".
Byte 6, 7, 8 have redundancy check (C1 C2 C3).
Your code seems good. Not tested it.

[tfroidcoeur]

byte 9 is general purpose, and is used for some flags if the card is formatted in MAD or NDEF

[padraig]

Hi There,

I'm new to mifare. We have have a smart card which uses KEY A to read and KEY B read/write.

Can you let me know the access bits HEX code to emulate this, using a new idworks application.

The default access bits code is FF0708 C1 C2 C3 = ( 0 0 1 ) but I'm not sure what the HEX code is for
C1C2C3 = ( 0 1 1 ).

Any Help would be appreciated,
Padraig.

[nadeem1414]

i have Nokia C1-02 which is absolutely good but there is a problem with me its capacity is not enough according my choice so what should i do for improve same set?