Method SetKey50

Libraries/unrar/crypt5.cpp:131–189

void CryptData::SetKey50(bool Encrypt,SecPassword *Password,const wchar *PwdW,
     const byte *Salt,const byte *InitV,uint Lg2Cnt,byte *HashKey,
     byte *PswCheck)
{
  if (Lg2Cnt>CRYPT5_KDF_LG2_COUNT_MAX)
    return;

  byte Key[32],PswCheckValue[SHA256_DIGEST_SIZE],HashKeyValue[SHA256_DIGEST_SIZE];
  bool Found=false;
  for (uint I=0;I<ASIZE(KDF5Cache);I++)
  {
    KDF5CacheItem *Item=KDF5Cache+I;
    if (Item->Lg2Count==Lg2Cnt && Item->Pwd==*Password &&
        memcmp(Item->Salt,Salt,SIZE_SALT50)==0)
    {
      memcpy(Key,Item->Key,sizeof(Key));
      SecHideData(Key,sizeof(Key),false,false);

      memcpy(PswCheckValue,Item->PswCheckValue,sizeof(PswCheckValue));
      memcpy(HashKeyValue,Item->HashKeyValue,sizeof(HashKeyValue));
      Found=true;
      break;
    }
  }

  if (!Found)
  {
    char PwdUtf[MAXPASSWORD*4];
    WideToUtf(PwdW,PwdUtf,ASIZE(PwdUtf));
    
    pbkdf2((byte *)PwdUtf,strlen(PwdUtf),Salt,SIZE_SALT50,Key,HashKeyValue,PswCheckValue,(1<<Lg2Cnt));
    cleandata(PwdUtf,sizeof(PwdUtf));

    KDF5CacheItem *Item=KDF5Cache+(KDF5CachePos++ % ASIZE(KDF5Cache));
    Item->Lg2Count=Lg2Cnt;
    Item->Pwd=*Password;
    memcpy(Item->Salt,Salt,SIZE_SALT50);
    memcpy(Item->Key,Key,sizeof(Item->Key));
    memcpy(Item->PswCheckValue,PswCheckValue,sizeof(PswCheckValue));
    memcpy(Item->HashKeyValue,HashKeyValue,sizeof(HashKeyValue));
    SecHideData(Item->Key,sizeof(Item->Key),true,false);
  }
  if (HashKey!=NULL)
    memcpy(HashKey,HashKeyValue,SHA256_DIGEST_SIZE);
  if (PswCheck!=NULL)
  {
    memset(PswCheck,0,SIZE_PSWCHECK);
    for (uint I=0;I<SHA256_DIGEST_SIZE;I++)
      PswCheck[I%SIZE_PSWCHECK]^=PswCheckValue[I];
    cleandata(PswCheckValue,sizeof(PswCheckValue));
  }

  // NULL initialization vector is possible if we only need the password
  // check value for archive encryption header.
  if (InitV!=NULL)
    rin.Init(Encrypt, Key, 256, InitV);

  cleandata(Key,sizeof(Key));