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/*
    dvb common scrambling algorithm
 
    refs:
        uk patent: gb 2322 994
        uk patent: gb 2322 995
        freedec v2.1
        iso/iec 13818-1
        etr289 / dvb document a007
 
*/
 
#include <memory.h>
#include <stdio.h>
#include "csa.h"
 
#include "misc.h"
 
#ifndef NULL
#define NULL 0
#endif
 
/* stream cypher */
 
/*  107 state bits */
/*  26 nibbles (4 bit) */
/*  +  3 bits */
/*  reg A[1]-A[10], 10 nibbles */
/*  reg B[1]-B[10], 10 nibbles */
/*  reg X,           1 nibble */
/*  reg Y,           1 nibble */
/*  reg Z,           1 nibble */
/*  reg D,           1 nibble */
/*  reg E,           1 nibble */
/*  reg F,           1 nibble */
/*  reg p,           1 bit */
/*  reg q,           1 bit */
/*  reg r,           1 bit */
 
int sbox1[0x20] = {2,0,1,1,2,3,3,0, 3,2,2,0,1,1,0,3, 0,3,3,0,2,2,1,1, 2,2,0,3,1,1,3,0};
int sbox2[0x20] = {3,1,0,2,2,3,3,0, 1,3,2,1,0,0,1,2, 3,1,0,3,3,2,0,2, 0,0,1,2,2,1,3,1};
int sbox3[0x20] = {2,0,1,2,2,3,3,1, 1,1,0,3,3,0,2,0, 1,3,0,1,3,0,2,2, 2,0,1,2,0,3,3,1};
int sbox4[0x20] = {3,1,2,3,0,2,1,2, 1,2,0,1,3,0,0,3, 1,0,3,1,2,3,0,3, 0,3,2,0,1,2,2,1};
int sbox5[0x20] = {2,0,0,1,3,2,3,2, 0,1,3,3,1,0,2,1, 2,3,2,0,0,3,1,1, 1,0,3,2,3,1,0,2};
int sbox6[0x20] = {0,1,2,3,1,2,2,0, 0,1,3,0,2,3,1,3, 2,3,0,2,3,0,1,1, 2,1,1,2,0,3,3,0};
int sbox7[0x20] = {0,3,2,2,3,0,0,1, 3,0,1,3,1,2,2,1, 1,0,3,3,0,1,1,2, 2,3,1,0,2,3,0,2};
 
void stream_cypher(int init, unsigned char *CK, unsigned char *sb, unsigned char *cb) {
    int i,j;
    int in1;        /*  most  significant nibble of input byte */
    int in2;        /*  least significant nibble of input byte */
    int op;
    int extra_B;
    int s1,s2,s3,s4,s5,s6,s7;
    int next_A1;
    int next_B1;
    int next_E;
 
    static int A[11];
    static int B[11];
    static int X;
    static int Y;
    static int Z;
    static int D;
    static int E;
    static int F;
    static int p;
    static int q;
    static int r;
 
    /*  reset */
    if (init) {
        /*  load first 32 bits of CK into A[1]..A[8] */
        /*  load last  32 bits of CK into B[1]..B[8] */
        /*  all other regs = 0 */
        A[1] = (CK[0] >> 4) & 0xf;
        A[2] = (CK[0] >> 0) & 0xf;
        A[3] = (CK[1] >> 4) & 0xf;
        A[4] = (CK[1] >> 0) & 0xf;
        A[5] = (CK[2] >> 4) & 0xf;
        A[6] = (CK[2] >> 0) & 0xf;
        A[7] = (CK[3] >> 4) & 0xf;
        A[8] = (CK[3] >> 0) & 0xf;
        A[9] = 0;
        A[10] = 0;
        B[1] = (CK[4] >> 4) & 0xf;
        B[2] = (CK[4] >> 0) & 0xf;
        B[3] = (CK[5] >> 4) & 0xf;
        B[4] = (CK[5] >> 0) & 0xf;
        B[5] = (CK[6] >> 4) & 0xf;
        B[6] = (CK[6] >> 0) & 0xf;
        B[7] = (CK[7] >> 4) & 0xf;
        B[8] = (CK[7] >> 0) & 0xf;
        B[9] = 0;
        B[10] = 0;
 
        X=0;
        Y=0;
        Z=0;
        D=0;
        E=0;
        F=0;
        p=0;
        q=0;
        r=0;
    } /* init */
 
 
 
    /*  8 bytes per operation */
    for(i=0; i<8; i++) {
        if (init) {
            in1 = (sb[i] >> 4) & 0x0f;
            in2 = (sb[i] >> 0) & 0x0f;
        } /* init */
        op = 0;
        /*  2 bits per iteration */
        for(j=0; j<4; j++) {
            /*  from A[1]..A[10], 35 bits are selected as inputs to 7 s-boxes */
            /*  5 bits input per s-box, 2 bits output per s-box */
            s1 = sbox1[ (((A[4]>>0)&1)<<4) | (((A[1]>>2)&1)<<3) | (((A[6]>>1)&1)<<2) | (((A[7]>>3)&1)<<1) | (((A[9]>>0)&1)<<0) ];
            s2 = sbox2[ (((A[2]>>1)&1)<<4) | (((A[3]>>2)&1)<<3) | (((A[6]>>3)&1)<<2) | (((A[7]>>0)&1)<<1) | (((A[9]>>1)&1)<<0) ];
            s3 = sbox3[ (((A[1]>>3)&1)<<4) | (((A[2]>>0)&1)<<3) | (((A[5]>>1)&1)<<2) | (((A[5]>>3)&1)<<1) | (((A[6]>>2)&1)<<0) ];
            s4 = sbox4[ (((A[3]>>3)&1)<<4) | (((A[1]>>1)&1)<<3) | (((A[2]>>3)&1)<<2) | (((A[4]>>2)&1)<<1) | (((A[8]>>0)&1)<<0) ];
            s5 = sbox5[ (((A[5]>>2)&1)<<4) | (((A[4]>>3)&1)<<3) | (((A[6]>>0)&1)<<2) | (((A[8]>>1)&1)<<1) | (((A[9]>>2)&1)<<0) ];
            s6 = sbox6[ (((A[3]>>1)&1)<<4) | (((A[4]>>1)&1)<<3) | (((A[5]>>0)&1)<<2) | (((A[7]>>2)&1)<<1) | (((A[9]>>3)&1)<<0) ];
            s7 = sbox7[ (((A[2]>>2)&1)<<4) | (((A[3]>>0)&1)<<3) | (((A[7]>>1)&1)<<2) | (((A[8]>>2)&1)<<1) | (((A[8]>>3)&1)<<0) ];
 
            /*  use 4x4 xor to produce extra nibble for T3 */
            extra_B = ( ((B[3]&1)<<3) ^ ((B[6]&2)<<2) ^ ((B[7]&4)<<1) ^ ((B[9]&8)>>0) ) |
                      ( ((B[6]&1)<<2) ^ ((B[8]&2)<<1) ^ ((B[3]&8)>>1) ^ ((B[4]&4)>>0) ) |
                      ( ((B[5]&8)>>2) ^ ((B[8]&4)>>1) ^ ((B[4]&1)<<1) ^ ((B[5]&2)>>0) ) |
                      ( ((B[9]&4)>>2) ^ ((B[6]&8)>>3) ^ ((B[3]&2)>>1) ^ ((B[8]&1)>>0) ) ;
 
            /*  T1 = xor all inputs */
            /*  in1,in2, D are only used in T1 during initialisation, not generation */
            next_A1 = A[10] ^ X;
            if (init)
                                next_A1 = next_A1 ^ D ^ ((j % 2) ? in2 : in1);
 
 
            /*  T2 =  xor all inputs */
            /*  in1,in2 are only used in T1 during initialisation, not generation */
            /*  if p=0, use this, if p=1, rotate the result left */
            next_B1 = B[7] ^ B[10] ^ Y;
            if (init)
                                next_B1 = next_B1 ^ ((j % 2) ? in1 : in2);
 
            /*  if p=1, rotate left */
            if (p)
                                next_B1 = ( (next_B1 << 1) | ((next_B1 >> 3) & 1) ) & 0xf;
 
            /*  T3 = xor all inputs */
            D = E ^ Z ^ extra_B;
 
            /*  T4 = sum, carry of Z + E + r */
            next_E = F;
            if (q) {
                F = Z + E + r;
                /*  r is the carry */
                r = (F >> 4) & 1;
                F = F & 0x0f;
            } /* q */
            else {
                F = E;
            }
            E = next_E;
 
            A[10] = A[9];
            A[9] = A[8];
            A[8] = A[7];
            A[7] = A[6];
            A[6] = A[5];
            A[5] = A[4];
            A[4] = A[3];
            A[3] = A[2];
            A[2] = A[1];
            A[1]= next_A1;
 
            B[10] = B[9];
            B[9] = B[8];
            B[8] = B[7];
            B[7] = B[6];
            B[6] = B[5];
            B[5] = B[4];
            B[4] = B[3];
            B[3] = B[2];
            B[2] = B[1];
            B[1] = next_B1;
 
            X = ((s4&1)<<3) | ((s3&1)<<2) | (s2&2) | ((s1&2)>>1);
            Y = ((s6&1)<<3) | ((s5&1)<<2) | (s4&2) | ((s3&2)>>1);
            Z = ((s2&1)<<3) | ((s1&1)<<2) | (s6&2) | ((s5&2)>>1);
            p = (s7&2)>>1;
            q = (s7&1);
 
            /*  require 4 loops per output byte */
            /*  2 output bits are a function of the 4 bits of D */
            /*  xor 2 by 2 */
            op = (op << 2)^ ( (((D^(D>>1))>>1)&2) | ((D^(D>>1))&1) );
        }
        /*  return input data during init */
        cb[i] = (init) ? sb[i] : op;
    }
}
 
/* block cypher */
 
/*  key preparation */
unsigned char key_perm[0x40] = {
    0x12,0x24,0x09,0x07,0x2A,0x31,0x1D,0x15,0x1C,0x36,0x3E,0x32,0x13,0x21,0x3B,0x40,
    0x18,0x14,0x25,0x27,0x02,0x35,0x1B,0x01,0x22,0x04,0x0D,0x0E,0x39,0x28,0x1A,0x29,
    0x33,0x23,0x34,0x0C,0x16,0x30,0x1E,0x3A,0x2D,0x1F,0x08,0x19,0x17,0x2F,0x3D,0x11,
    0x3C,0x05,0x38,0x2B,0x0B,0x06,0x0A,0x2C,0x20,0x3F,0x2E,0x0F,0x03,0x26,0x10,0x37,
};
 
/*  block - sbox */
unsigned char block_sbox[0x100] = {
    0x3A,0xEA,0x68,0xFE,0x33,0xE9,0x88,0x1A,0x83,0xCF,0xE1,0x7F,0xBA,0xE2,0x38,0x12,
    0xE8,0x27,0x61,0x95,0x0C,0x36,0xE5,0x70,0xA2,0x06,0x82,0x7C,0x17,0xA3,0x26,0x49,
    0xBE,0x7A,0x6D,0x47,0xC1,0x51,0x8F,0xF3,0xCC,0x5B,0x67,0xBD,0xCD,0x18,0x08,0xC9,
    0xFF,0x69,0xEF,0x03,0x4E,0x48,0x4A,0x84,0x3F,0xB4,0x10,0x04,0xDC,0xF5,0x5C,0xC6,
    0x16,0xAB,0xAC,0x4C,0xF1,0x6A,0x2F,0x3C,0x3B,0xD4,0xD5,0x94,0xD0,0xC4,0x63,0x62,
    0x71,0xA1,0xF9,0x4F,0x2E,0xAA,0xC5,0x56,0xE3,0x39,0x93,0xCE,0x65,0x64,0xE4,0x58,
    0x6C,0x19,0x42,0x79,0xDD,0xEE,0x96,0xF6,0x8A,0xEC,0x1E,0x85,0x53,0x45,0xDE,0xBB,
    0x7E,0x0A,0x9A,0x13,0x2A,0x9D,0xC2,0x5E,0x5A,0x1F,0x32,0x35,0x9C,0xA8,0x73,0x30,
 
    0x29,0x3D,0xE7,0x92,0x87,0x1B,0x2B,0x4B,0xA5,0x57,0x97,0x40,0x15,0xE6,0xBC,0x0E,
    0xEB,0xC3,0x34,0x2D,0xB8,0x44,0x25,0xA4,0x1C,0xC7,0x23,0xED,0x90,0x6E,0x50,0x00,
    0x99,0x9E,0x4D,0xD9,0xDA,0x8D,0x6F,0x5F,0x3E,0xD7,0x21,0x74,0x86,0xDF,0x6B,0x05,
    0x8E,0x5D,0x37,0x11,0xD2,0x28,0x75,0xD6,0xA7,0x77,0x24,0xBF,0xF0,0xB0,0x02,0xB7,
    0xF8,0xFC,0x81,0x09,0xB1,0x01,0x76,0x91,0x7D,0x0F,0xC8,0xA0,0xF2,0xCB,0x78,0x60,
    0xD1,0xF7,0xE0,0xB5,0x98,0x22,0xB3,0x20,0x1D,0xA6,0xDB,0x7B,0x59,0x9F,0xAE,0x31,
    0xFB,0xD3,0xB6,0xCA,0x43,0x72,0x07,0xF4,0xD8,0x41,0x14,0x55,0x0D,0x54,0x8B,0xB9,
    0xAD,0x46,0x0B,0xAF,0x80,0x52,0x2C,0xFA,0x8C,0x89,0x66,0xFD,0xB2,0xA9,0x9B,0xC0,
};
 
/*  block - perm */
unsigned long block_perm[0x100] = {
    0x00,0x02,0x80,0x82,0x20,0x22,0xA0,0xA2, 0x10,0x12,0x90,0x92,0x30,0x32,0xB0,0xB2,
    0x04,0x06,0x84,0x86,0x24,0x26,0xA4,0xA6, 0x14,0x16,0x94,0x96,0x34,0x36,0xB4,0xB6,
    0x40,0x42,0xC0,0xC2,0x60,0x62,0xE0,0xE2, 0x50,0x52,0xD0,0xD2,0x70,0x72,0xF0,0xF2,
    0x44,0x46,0xC4,0xC6,0x64,0x66,0xE4,0xE6, 0x54,0x56,0xD4,0xD6,0x74,0x76,0xF4,0xF6,
    0x01,0x03,0x81,0x83,0x21,0x23,0xA1,0xA3, 0x11,0x13,0x91,0x93,0x31,0x33,0xB1,0xB3,
    0x05,0x07,0x85,0x87,0x25,0x27,0xA5,0xA7, 0x15,0x17,0x95,0x97,0x35,0x37,0xB5,0xB7,
    0x41,0x43,0xC1,0xC3,0x61,0x63,0xE1,0xE3, 0x51,0x53,0xD1,0xD3,0x71,0x73,0xF1,0xF3,
    0x45,0x47,0xC5,0xC7,0x65,0x67,0xE5,0xE7, 0x55,0x57,0xD5,0xD7,0x75,0x77,0xF5,0xF7,
 
    0x08,0x0A,0x88,0x8A,0x28,0x2A,0xA8,0xAA, 0x18,0x1A,0x98,0x9A,0x38,0x3A,0xB8,0xBA,
    0x0C,0x0E,0x8C,0x8E,0x2C,0x2E,0xAC,0xAE, 0x1C,0x1E,0x9C,0x9E,0x3C,0x3E,0xBC,0xBE,
    0x48,0x4A,0xC8,0xCA,0x68,0x6A,0xE8,0xEA, 0x58,0x5A,0xD8,0xDA,0x78,0x7A,0xF8,0xFA,
    0x4C,0x4E,0xCC,0xCE,0x6C,0x6E,0xEC,0xEE, 0x5C,0x5E,0xDC,0xDE,0x7C,0x7E,0xFC,0xFE,
    0x09,0x0B,0x89,0x8B,0x29,0x2B,0xA9,0xAB, 0x19,0x1B,0x99,0x9B,0x39,0x3B,0xB9,0xBB,
    0x0D,0x0F,0x8D,0x8F,0x2D,0x2F,0xAD,0xAF, 0x1D,0x1F,0x9D,0x9F,0x3D,0x3F,0xBD,0xBF,
    0x49,0x4B,0xC9,0xCB,0x69,0x6B,0xE9,0xEB, 0x59,0x5B,0xD9,0xDB,0x79,0x7B,0xF9,0xFB,
    0x4D,0x4F,0xCD,0xCF,0x6D,0x6F,0xED,0xEF, 0x5D,0x5F,0xDD,0xDF,0x7D,0x7F,0xFD,0xFF,
};
 
void key_schedule(unsigned char *CK, int *kk) 
{
    int i,j,k;
    int bit[64];
    int newbit[64];
    int kb[9][8];
 
    DEBUG_OUTPUT_ARR(CK,8);
 
    /*  56 steps */
    /*  56 key bytes kk(56)..kk(1) by key schedule from CK */
 
    /*  kb(7,1) .. kb(7,8) = CK(1) .. CK(8) */
    kb[7][1] = CK[0];
    kb[7][2] = CK[1];
    kb[7][3] = CK[2];
    kb[7][4] = CK[3];
    kb[7][5] = CK[4];
    kb[7][6] = CK[5];
    kb[7][7] = CK[6];
    kb[7][8] = CK[7];
 
    /*  calculate kb[6] .. kb[1] */
    for(i=0; i<7; i++) {
        /*  64 bit perm on kb */
        for(j=0; j<8; j++) {
            for(k=0; k<8; k++) {
                bit[j*8+k] = (kb[7-i][1+j] >> (7-k)) & 1;
                newbit[key_perm[j*8+k]-1] = bit[j*8+k];
            }
        }
        for(j=0; j<8; j++) {
            kb[6-i][1+j] = 0;
            for(k=0; k<8; k++) {
                kb[6-i][1+j] |= newbit[j*8+k] << (7-k);
            }
        }
    }
 
    /*  xor to give kk */
    for(i=0; i<7; i++) {
        for(j=0; j<8; j++) {
            kk[1+i*8+j] = kb[1+i][1+j] ^ i;
        }
    }
}
 
void block_decypher(int *kk, unsigned char *ib, unsigned char *bd) {
    int i;
    int sbox_in;
    int sbox_out;
    int perm_out;
    int R[9];
    int next_R8;
 
    R[1] = ib[0];
    R[2] = ib[1];
    R[3] = ib[2];
    R[4] = ib[3];
    R[5] = ib[4];
    R[6] = ib[5];
    R[7] = ib[6];
    R[8] = ib[7];
 
    /*  loop over kk[56]..kk[1] */
    for(i=56; i>0; i--) {
        sbox_in = kk[i] ^ R[7];
        sbox_out = block_sbox[sbox_in];
        perm_out = block_perm[sbox_out];
 
        next_R8 = R[7];
        R[7] = R[6] ^ perm_out;
        R[6] = R[5];
        R[5] = R[4] ^ R[8] ^ sbox_out;
        R[4] = R[3] ^ R[8] ^ sbox_out;
        R[3] = R[2] ^ R[8] ^ sbox_out;
        R[2] = R[1];
        R[1] = R[8] ^ sbox_out;
 
        R[8] = next_R8;
    }
 
    bd[0] = R[1];
    bd[1] = R[2];
    bd[2] = R[3];
    bd[3] = R[4];
    bd[4] = R[5];
    bd[5] = R[6];
    bd[6] = R[7];
    bd[7] = R[8];
 
}
 
void set_cws(unsigned char *cws, struct key *key) {
        memcpy(key->odd_ck,cws+8,8);
        memcpy(key->even_ck,cws,8);
        key_schedule(key->odd_ck,key->odd_kk);
        key_schedule(key->even_ck,key->even_kk);
        DEBUG_OUTPUT_ARR(key->even_kk,57);
        DEBUG_OUTPUT_ARR(key->odd_kk,57);
}
 
void decrypt(struct key *key, unsigned char *encrypted, unsigned char *decrypted) {
    int i,j,offset=4,N;
    int *kk=key->even_kk;
    unsigned char *ck=key->even_ck;
    unsigned char stream[8];
    unsigned char ib[8];
    unsigned char block[8];
    int residue;
 
        ((unsigned long *) decrypted)[0]=((unsigned long *) encrypted)[0];
 
        if(decrypted[3]&0x40) {
                kk=key->odd_kk;
                ck=key->odd_ck;
        }
 
    decrypted[3] &= 0x3f;              /* remove scrambling bits */
 
    if ((decrypted[3] & 0x20) == 0x20)
      offset += (encrypted[4] +1);               /* skip adaption field */
 
    N = (188 - offset) / 8;
    residue = (188 - 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(ib,8);
                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;
        }
 
#if 0
              fprintf(stderr,"output \n");
           DEBUG_OUTPUT_ARR(ib,8);
           DEBUG_OUTPUT_ARR(block,8);
           #endif
 
        /*  xor ib x block */
        for(i=0; i<8; i++)
                 decrypted[offset+8*(j-1)+i] = ib[i] ^ block[i];
    } /* for(j=1; j<(N+1); j++) */
 
    if (residue) {
       stream_cypher(0, ck, NULL, stream);
       for (i=0;i<residue;i++)
        decrypted[188-residue+i] = encrypted[188-residue+i] ^ stream[i];
    }
 
}