/*--------------------------------------------------------------------
!
!       Blowfish.c
!
!       Copyright 2002 by MegaChips Corporation
!
!---------------------------------------------------------------------
!       PROJECT: IRIS Demo
!      CATEGORY: C source
!       COMMENT: Blowfish subroutine
!       $Author: kawamura.kumiko $
!         $Date: 2002/12/02 08:13:54 $
!     $Revision: 1.2 $
!--
*/
#include "blowfish.h"


#define MAXKEYBYTES	56          /* 448 bits */
#define	N		16


static u32 F(const BLOWFISH_CTX *ctx, u32 x);

void InitBlowfish(BLOWFISH_CTX *ctx, const unsigned char *key, int keyLen)
{
  int i, j, k;
  u32 data, datal, datar;

  j = 0;
  for (i = 0; i < N + 2; ++i) {
    data = 0x00000000;
    for (k = 0; k < 4; ++k) {
      data = (data << 8) | key[j];
      j = j + 1;
      if (j >= keyLen)
        j = 0;
    }
    ctx->P[i] = ctx->P[i] ^ data;
  }

  datal = 0x00000000;
  datar = 0x00000000;

  for (i = 0; i < N + 2; i += 2) {
    EncryptByBlowfish(ctx, &datal, &datar);
    ctx->P[i] = datal;
    ctx->P[i + 1] = datar;
  }

  for (i = 0; i < 4; ++i) {
    for (j = 0; j < 256; j += 2) {
      EncryptByBlowfish(ctx, &datal, &datar);
      ctx->S[i][j] = datal;
      ctx->S[i][j + 1] = datar;
    }
  }

}


void EncryptByBlowfish(const BLOWFISH_CTX *ctx, u32 *xl, u32 *xr)
{
  u32  Xl;
  u32  Xr;
  u32  temp;
  int       i;

  Xl = *xl;
  Xr = *xr;

  for (i = 0; i < N; ++i) {
    Xl = Xl ^ ctx->P[i];
    Xr = F(ctx, Xl) ^ Xr;

    temp = Xl;

    Xl = Xr;
    Xr = temp;
  }

  temp = Xl;
  Xl = Xr;
  Xr = temp;

  Xr = Xr ^ ctx->P[N];
  Xl = Xl ^ ctx->P[N + 1];
  
  *xl = Xl;
  *xr = Xr;
}

void DecryptByBlowfish(const BLOWFISH_CTX *ctx, u32 *xl, u32 *xr)
{
  u32  Xl;
  u32  Xr;
  u32  temp;
  int       i;


  Xl = *xl;
  Xr = *xr;

  for (i = N + 1; i > 1; --i) {
    Xl = Xl ^ ctx->P[i];
    Xr = F(ctx, Xl) ^ Xr;

    temp = Xl;
    Xl = Xr;
    Xr = temp;
  }

  temp = Xl;
  Xl = Xr;
  Xr = temp;

  Xr = Xr ^ ctx->P[1];
  Xl = Xl ^ ctx->P[0];

  *xl = Xl;
  *xr = Xr;
}


static u32 F(const BLOWFISH_CTX *ctx, u32 x) {
   u32  a, b, c, d;
   u32  y;

   d = x & 0x00FF;
   x >>= 8;

   c = x & 0x00FF;
   x >>= 8;

   b = x & 0x00FF;
   x >>= 8;

   a = x & 0x00FF;

   y = ctx->S[0][a] + ctx->S[1][b];

   y = y ^ ctx->S[2][c];
   y = y + ctx->S[3][d];

   return y;
}