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Thread: quick, semi-secure encryption/decryption?

  1. #1

    Thread Starter
    Frenzied Member
    Join Date
    Aug 2000
    Posts
    1,091
    Hi,

    I have a 2MB text file that I need to be able to encrypt/decrypt quickly so the user does not have to wait too long..

    The idea is to just keep the casual user from looking at the text file directly.. If a hacker can crack the code, then oh well.. No biggy.. My priority is speed and then encryption..

    As an alternative, is it possible to compile a text file within the executable? The text will not ever change.. Probably not, but I just thought I'd ask..

    I used the CryptoAPI module found at freevbcode.com but it took so long it locked up my computer..

    When replying, please keep in mind that I'm new to this subject so I need example code to go along with your suggestions..

    Thanks,

    Dan

  2. #2
    _______ HeSaidJoe's Avatar
    Join Date
    Jun 1999
    Location
    Canada
    Posts
    3,946

    <?>

    Code:
    'Encrypt/Unencrypt a file
    '
    Option Explicit
    '
    Private Function EncryptFile(sFile As String, iKey As Integer)
    
        Dim iFake#
        Dim x As String * 1
         
        Dim lP As Long, z
        Dim intNum#
        intNum = FreeFile
    
        iFake = Rnd(-1)
        Randomize (iKey)
         
         
        lP = 1
        Open sFile For Binary As intNum
         
        While lP <= LOF(intNum)
         
        Get #intNum, lP, x
         
        z = Asc(x) + Int(Rnd * 256)
        If z > 255 Then z = z - 256
         
        x = Chr(z)
         
        Put #intNum, lP, x
         
        lP = lP + 1
         
         
        Wend
         
        Close #intNum
    
        MsgBox "Your file has been encrypted."
    
    End Function
    
    
    Private Function DecryptFile(sFile As String, iKey As Integer)
    
        Dim iFake As Integer
        Dim x As String * 1
         
        Dim lP As Long, z
        Dim intNum#
        
        intNum = FreeFile
      
        iFake = Rnd(-1)
        Randomize (iKey)
         
         
        lP = 1
        Open sFile For Binary As #intNum
         
        While lP <= LOF(intNum)
         
        Get #intNum, lP, x
         
        z = Asc(x) - Int(Rnd * 256)
        If z < 0 Then z = z + 256
         
        x = Chr(z)
         
        Put #intNum, lP, x
         
        lP = lP + 1
         
        Wend
         
        Close #intNum
        
        MsgBox "Your file has been unencrypted."
        
    End Function
    
    ' <<<<   Form Event Code    >>>>
    
    
    Private Sub Command1_Click()
    'encrypt the file
        Call EncryptFile("C:\myFile.txt", 44)
    
    End Sub
    
    Private Sub Command2_Click()
    'decrypt the file
        Call DecryptFile("c:\myFile.txt", 44)
    
    End Sub
    "A myth is not the succession of individual images,
    but an integerated meaningful entity,
    reflecting a distinct aspect of the real world."

    ___ Adolf Jensen

  3. #3

    Thread Starter
    Frenzied Member
    Join Date
    Aug 2000
    Posts
    1,091
    Thanks! works great..

    Now, how would I modify it to just decrypt it into memory into a string variable while leaving the actual file encrypted?

    Thanks,

    Dan


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