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/*

 * =====================================================================================

 *

 *       Filename:  group_decrypt.c

 *

 *    Description:  test group decryp module

 *

 *        Version:  1.0

 *        Created:  04/25/2009 11:56:00 AM

 *       Revision:  none

 *       Compiler:  gcc

 *

 *         Author:  mengxipeng@gmail.com

 *

 * =====================================================================================

 */

#include <stdio.h>

#include <string.h>

#include "misc.h"

#include "csa.h"

void key_schedule(unsigned char *CK, int *kk) ;

void stream_cypher(int init, unsigned char *CK, unsigned char *sb, unsigned char *cb) ;

void block_decypher(int *kk, unsigned char *ib, unsigned char *bd) ;

int main()

{

        unsigned char ck[8];

        int kk[57];

        unsigned char encrypted[184];

        unsigned char decrypted[184];

        READ_DATA(ck,8);

        key_schedule(ck,kk);

        READ_DATA(encrypted,184);

        {

                int i,j,offset=0,N;

                unsigned char stream[8];

                unsigned char ib[8];

                unsigned char block[8];

                int residue;

                N = (184 - offset) / 8;

                residue = (184 - offset) % 8;

                /*  1st 8 bytes of initialisation */

                stream_cypher(1, ck, &encrypted[offset], ib);

                for(j=1; j<(N+1); j++) {

                        block_decypher(kk, ib, block);

                        DEBUG_OUTPUT_ARR(block,8);

                        if (j != N) {

                                stream_cypher(0, ck, NULL, stream);

                                /*  xor sb x stream */

                                for(i=0; i<8; i++)

                                        ib[i] = encrypted[offset+8*j+i] ^ stream[i];

                        }

                        else {

                                /*  last block - sb[N+1] = IV(initialisation vetor)(=0) */

                                for(i=0; i<8; i++)  ib[i] = 0;

                        }

                        /*  xor ib x block */

                        for(i=0; i<8; i++)

                                decrypted[offset+8*(j-1)+i] = ib[i] ^ block[i];

                        DEBUG_OUTPUT_ARR(&decrypted[offset+8*(j-1)+0],8);

                } /* for(j=1; j<(N+1); j++) */

                if (residue) {

                        stream_cypher(0, ck, NULL, stream);

                        for (i=0;i<residue;i++)

                                decrypted[184-residue+i] = encrypted[184-residue+i] ^ stream[i];

                }

        }

        WRITE_DATA(decrypted,184);

        return 0;

}