🚀 go-pugleaf

Everything seemed fine using the below code to initialize the CSP and being
called with
CMyCrypto myCrypto((LPSTR)thekey.c_str(), CALG_RC4);

/////////////////////////////////////////////////////////
CMyCrypto::CMyCrypto(LPTSTR pszPassword, ALG_ID algorithm)
{
    m_hProv = NULL;
    m_hKey  = NULL;
    // Get handle to the default key container in default CSP
    if (CryptAcquireContext(&m_hProv,     // handle to CSP
                            NULL,         // default container
                            MS_DEF_PROV,  // default CSP
                            PROV_RSA_FULL,// provider type
                            0)) {         // action
//// here i set CRYPT_NEWKEYSET ////

        HCRYPTHASH hHash;

        // Get handle to hash object
        if (CryptCreateHash(m_hProv,   // handle to CSP
                            CALG_MD5,  // hashing algorithm
                            0,         // non-keyed hash
                            0,         // reserved, must be zero
                            &hHash)) { // hash object

            // Hash the password
            if (CryptHashData(hHash,   // handle to hash object
                              (LPBYTE)pszPassword, // data buffer
                              lstrlen(pszPassword)*sizeof(TCHAR),
                              0)) {    // flags

                // Create the session key using the hashed password
                CryptDeriveKey(m_hProv,   // handle to CSP
                               algorithm, // encryption algorithm
                               hHash,     // hashed data
                               CRYPT_EXPORTABLE | 0x00280000,
                               &m_hKey);  // session key
            }
            CryptDestroyHash(hHash);
        }
    }
}
/////////////////////////////////////////////////////////////

However when i tried the same program on a newly installed version of XP the
CryptAcquireContext() return false.
I tried with the action set as CRYPT_NEWKEYSET rather than 0 and then
retried with it set to 0 again and it worked..
so i am under the impression that if the function fails then recall with
CRYPT_NEWKEYSET and then start over.. as just carrying on after using
CRYPT_NEWKEYSET did not work.
My main concern however that is if i do it this way is that one pc will be
sending crypted commands and files to another..will they choose different
providers and even though they both use the same keystr for dec/encryption
hows it going to decrypt correctly when using different providers or do i
have to make sure it uses CRYPT_NEWKEYSET to use the same provider...sorry
for the lack of knowledge here but its my virgin run at it..



"Remy Lebeau (TeamB)" <no.spam@no.spam.com> wrote in message
news:41a385b5$1@newsgroups.borland.com...
>
> "roger" <rogersmail@ntlworld.com> wrote in message
> news:41a37ce2$1@newsgroups.borland.com...
>
>
> >     dwDataLen = stringsin->Strings[a].Length();
> >     dwEncLen = dwDataLen;
> >     dwDataLen = stringsin->Strings[a].Length();
>
> The second assignment to dwDataLen is redundant.  It already has the value
> of Length().
>
> >     szData = new CHAR[dwEncLen + 1];
>
> You are allocating a buffer...
>
> >      szData = NULL;
>
> Yet you are then nullifying the pointer withoug actually freeing it.
>
> >      delete[] szData;
>
> szData is NULL by this point.
>
> >     if (bEncrypt) {
> >         if (myCrypto.Encrypt((BYTE*)szData,&dwDataLen,dwDataLen,true))
> >                  stringsout->Add(StrPas(szData));
> >       } else {
> >         if (myCrypto.Decrypt((BYTE*)szData,&dwDataLen, true))
> >                 stringsout->Add(StrPas(szData));
> >              }
>
> You don't need to use StrPas().  It is an obsolete function.  Just pass
the
> char* pointer directly, it will be converted to AnsiString automatically
for
> you:
>
>     stringsout->Add(szData);
>
> Also, for your encryption, what does the actual encrypted data look like?
> Are there are '\0' characters in it?  There most likely is.  That would
> account for the incomplete data being passed back to the TStringList,
since
> you are not taking '\0' characters into account at all.
>
> Try this code instead (untested):
>
>     void __fastcall TForm1::CryptStringList(TStrings* stringsin, TStrings*
> stringsout, const AnsiString &thekey)
>     {
>         DWORD dwDataLen, dwEncLen;
>         AnsiString asData;
>         bool bOk;
>         CMyCrypto myCrypto(thekey.c_str(), CALG_RC4);
>
>         stringsout->BeginUpdate();
>         try
>         {
>             for(int a = 0; a < stringsin->Count; ++a)
>             {
>                 dwDataLen = stringsin->Strings[a].Length();
>                 dwEncLen = dwDataLen;
>
>                 bOk = !bEncrypt;
>                 if( !bOk )
>                     bOk = myCrypto.Encrypt(NULL, &dwEncLen, 0, true);
>
>                 if( bOk )
>                 {
>                     if( dwEncLen < dwDataLen )
>                         asData.SetLength(dwDataLen);
>                     else
>                         asData.SetLength(dwEncLen);
>
>                     strncpy(asData.c_str(), stringsin->Strings[a].c_str(),
> dwDataLen);
>
>                     if( bEncrypt )
>                         bOk = myCrypto.Encrypt((BYTE*)szData.c_str(),
> &dwDataLen, asData.Length(), true);
>                     else
>                         bOk = myCrypto.Decrypt((BYTE*)szData.c_str(),
> &dwDataLen, true);
>
>                     if( bOk )
>                     {
>                         asData.SetLength(dwDataLen);
>                         stringsout->Add(asData);
>                     }
>                 }
>             }
>         }
>         __finally {
>             stringsout->EndUpdate();
>         }
>     }
>
>
> Gambit
>
>