悪名高き車輪再開発屋d金魚作品No2 Arcfour暗号 エンコード デコード

Arcfour Algorithm
language type : ISO/IEC 9899:1999 - Programming Language C
source code licence : NYSL
note : 分からない識別子や関数等(例えば DKC_INLINEとかdkcFreeとか)はdkutil_cにて調べてください＾＾；；；；
開発中dkutil_c
http://cvs.sourceforge.jp/cgi-bin/viewcvs.cgi/dkingyoutility/dkutil/dkutil_c/
STABLE RELEASE
http://www.vector.co.jp/soft/win95/prog/se326918.html

///arcfour algprithm state (RC4互換のアルゴリズム

typedef struct dkc_Arcfour_State{

  unsigned char mi;

  unsigned char mj;

  unsigned char msbox[256];

}DKC_ARCFOUR_STATE;
DKC_ARCFOUR_STATE *WINAPI dkcAllocArcfour(

  const unsigned char *key,size_t keylen)

{
  int i,j;

  unsigned char temp;

  unsigned char *sb1,sb2[256];

  DKC_ARCFOUR_STATE *p;

  

  memset(sb2,0,sizeof(sb2));

  //allocate state struct

  p = dkcAllocate(sizeof(DKC_ARCFOUR_STATE));

  if(NULL==p){

    return NULL;

  }

  sb1 = p->msbox;

  

  //initialize

  for(i=0;i<256;i++){

    sb1[i] = (unsigned char)i;

    //嗅ぎ回られないように(なんか、意味あるのか？ないナァ？

    //p->msbox2[i] = key [i % keylen];

  }

  j=i=0;

  

  for(;j<256;j++){

    sb2[j] = key [j % keylen];

  }


  for(i=0;i<256;i++){

    //j = (j + sb1 [i] + sb2 [i]) % 256;

    j = (j + sb1[i] + sb2[i]) & 0xff;

    temp = sb1 [i];

    sb1 [i] = sb1 [j];

    sb1 [j] = temp;

    /*sb1[i] = sb1[j] - sb1[i] ;

    sb1[j] -= sb1[i] ;

    sb1[i] += sb1[j] ;*/

  //SWAP_NUM(sb1[i],sb1[j]);

  }

  return p;

}
DKC_EXTERN unsigned char WINAPI dkcArcfourByte(DKC_ARCFOUR_STATE *p){

  unsigned char i,j,temp;

  unsigned char *sb1 = p->msbox;

  

  //calc

  i = (unsigned char )(p->mi+1);// % 256;

  j = (unsigned char )(p->mj + sb1[i]);// % 256;

  

   //swap

  temp = sb1 [i];

  sb1 [i] = sb1 [j];

  sb1 [j] = temp;
  //SWAP_NUM(sb1[i],sb1[j]);

  //refresh

  p->mi = i;

  p->mj = j;

  //calc

  i = (unsigned char )(sb1 [i] + sb1 [j]);// % 256;

  j = (unsigned char )sb1[i];

  return j;

}
static DKC_INLINE void dkcArcfourEncrypt_Base(DKC_ARCFOUR_STATE *p,

  unsigned char *dest,unsigned const char *src,size_t srcsize)

{
  size_t cc;

  unsigned char i,j;

  unsigned char *sb1 = p->msbox;

  unsigned char temp;

  

    //calc

  i = (unsigned char )(p->mi);

  j = (unsigned char )(p->mj);
  for(cc = 0;cc < srcsize;cc++){

        //calc

    i = (unsigned char )(i+1);

    j = (unsigned char )(j + sb1[i]);

  

     //swap

    

    temp = sb1 [i];

    sb1 [i] = sb1 [j];

    sb1 [j] = temp;

    
    //SWAP_NUM_EX(sb1[i],sb1[j],unsigned char);
    //calc

    dest[cc] = (unsigned char )

      (src[cc] ^ (unsigned char )sb1[

        (unsigned char )(sb1 [i] + sb1 [j]) 

      ] 

    );

  }

  //refresh

  p->mi = i;

  p->mj = j;
}
int WINAPI dkcArcfourEncrypt(DKC_ARCFOUR_STATE *p,

  unsigned char *dest,size_t destsize,

  const unsigned char *src,size_t srcsize)

{

  //size_t i=0;

  if(destsize < srcsize){

    return edk_BufferOverFlow;

  }

  dkcArcfourEncrypt_Base(p,dest,src,srcsize);
  /*for(i = 0;i < srcsize;i++){

    dest[i] = (unsigned char )(src[i] ^ dkcArcfourByte(p) );

  }*/
  return edk_SUCCEEDED;

}




void WINAPI dkcArcfourEncryptNoDest(DKC_ARCFOUR_STATE *p,

  unsigned char *dest_and_src,size_t dest_and_srcsize)

{

  dkcArcfourEncrypt_Base(p,dest_and_src,dest_and_src,dest_and_srcsize);

}
int WINAPI dkcFreeArcfour(DKC_ARCFOUR_STATE **p){

  if(NULL==p){

    return edk_FAILED;

  }

  return dkcFree(p);

}