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(KDFCache);I++)
{
KDFCacheItem *Item=KDFCache+I;
if (Item->Lg2Count==Lg2Cnt && Item->Pwd==*Password &&
memcmp(Item->Salt,Salt,SIZE_SALT50)==0)
{
SecHideData(Item->Key,sizeof(Item->Key),false);
memcpy(Key,Item->Key,sizeof(Key));
SecHideData(Item->Key,sizeof(Item->Key),true);
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));
KDFCacheItem *Item=KDFCache+(KDFCachePos++ % ASIZE(KDFCache));
Item->Lg2Count=Lg2Cnt;
Item->Pwd=*Password;
memcpy(Item->Salt,Salt,SIZE_SALT50);
memcpy(Item->Key,Key,sizeof(Key));
memcpy(Item->PswCheckValue,PswCheckValue,sizeof(PswCheckValue));
memcpy(Item->HashKeyValue,HashKeyValue,sizeof(HashKeyValue));
SecHideData(Item->Key,sizeof(Key),true);
}
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));
}
// We got a complain from user that it is possible to create WinRAR dump
// with "Create dump file" command in Windows Task Manager and then easily
// locate Unicode password string in the dump. It is unsecure if several
// people share the same computer and somebody left WinRAR copy with entered
// password. So we decided to obfuscate the password to make it more difficult
// to find it in dump.
void SecPassword::Process(const wchar *Src,size_t SrcSize,wchar *Dst,size_t DstSize,bool Encode)
{
// Source string can be shorter than destination as in case when we process
// -p<pwd> parameter, so we need to take into account both sizes.
memcpy(Dst,Src,Min(SrcSize,DstSize)*sizeof(*Dst));
SecHideData(Dst,DstSize*sizeof(*Dst),Encode,CrossProcess);
}
