[MFC] How to encryption/decryption a CString?

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VS2010

Dear all:

I'd like to encryption & decryption a password for CString on MFC, having searched the problem on google; However, I can't find a solution I can use...
The encrypted string is not very important so I only need a easiest way to encrypt & decrypt it.
I hope someone could give me a suggestion.

Thanks a lot!!

Sincerely,

Hughes

Posted 17-Nov-14 16:54pm

Member 10307999

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Garth J Lancaster · Accepted Answer · 2014-11-17T17:04:00

Solution 1

A simple MFC class to encrypt data with the Crypto API[^]

Posted 17-Nov-14 17:04pm

Garth J Lancaster

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Member 10307999 18-Nov-14 23:07pm

Hi Lancaster,
Thanks for your reply! I've research the essay you posted, and I can encrypt & decrypt a CString like:
[Head file]
CCrypto crypto;
CByteArray arBytes;
[cpp file]
void CEncryptionDlg::OnBnClickedButton_Encrypt()
{
crypto.DeriveKey(_T("ABCD"));
CString sPassword=_T("Hello");
crypto.Encrypt(sPassword,arBytes);
}
void CEncryptionDlg::OnBnClickedButton_Decrypt()
{
CString strDecrypted;
crypto.Decrypt(arBytes, strDecrypted);
MessageBox(strDecrypted, _T("Notify"), MB_OK);
}

And then, I want to save the sPassword but the type of data is CByteArray between the encrypt() and decrypt().
If I want to save the CByteArray in a txt file, I gotta transform into CString.
It failed it...

my code:
[Head file]
CCrypto crypto;
CString sContent;
[cpp file]
void CEncryptionDlg::OnBnClickedButton_EncryptString()
{
crypto.DeriveKey(_T("ABCDEF"));
CString sPassword=_T("Hi");
CByteArray arBytes2;
crypto.Encrypt(sPassword,arBytes2);
CString str2(arBytes2.GetData()); //CByteArray to CString
sTest=str2;
}
void CEncryptionDlg::OnBnClickedButton_DecryptString()
{
CByteArray byteArr;
//CString to CByteArray --- start
BYTE *pByteArray = (PBYTE)(LPCTSTR)sTest.GetBuffer();
byteArr.SetSize(sTest.GetLength());
memcpy(byteArr.GetData(), pByteArray, sTest.GetLength());
//CString to CByteArray --- end

CString sDecrypted;
crypto.Decrypt(byteArr, sDecrypted);
MessageBox(sDecrypted, _T("Notify"), MB_OK);
}

But the sDecryprted is NOT "Hi" I want to get :(
Could someone give me some suggestions?
Thanks!!!

Garth J Lancaster 19-Nov-14 4:31am

I disagree with this

>> If I want to save the CByteArray in a txt file, I gotta transform into CString.

what is the rationale for that - you cant guarantee that the encrypted string contains human readable characters, so writing it to a text file ? (and if I were contemplating writing it to a text file given my previous comment I'd likely be base64 encoding it, but that's a different matter)

I would be writing it to a binary file - and avoiding the conversion back to CString - there's a lot we don't know about your project, for example, are you working in Unicode/UUTF-16, or ANSI, UTF-8 or ??? for example

// ** Untested **

CFile myFile;
CString strFileName = _T("Some File Name.dat");

// Write To File
if(myFile.Open(_T(strFileName), CFile::modeWrite | CFile::typeBinary | CFile::modeCreate))
{
myFile.Write(byteArr.GetData(),byteArr.GetSize());
}

// Read From File
CByteArray bytesFromFile;
if(myFile.Open(_T(strFileName), CFile::modeRead | CFile::typeBinary))
{
bytesFromFile.SetSize(1024); // ensure that buffer is allocated and the size we want it
UINT bytesRead = myFile.Read(bytesFromFile.GetData(), bytesFromFile.GetSize());
}

Member 10307999 24-Nov-14 22:06pm

Many thanks :)

[MFC] How to encryption/decryption a CString?

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[MFC] How to encryption/decryption a CString?

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