Load File into stream and Decrypt

I need to load a file into a varible type System.IO.Stream and then decrypt it (or decrypt it and then load it into a stream). I need to know whats the best encryption for the job. Baiscly I dont want to store the file on the users hard drive.

Any one have any source or links that could help? Is this even possible?

figured out how to load a file into a Stream now i just need to figure out a good encryption / decryption method

using the class crypto.vb

VB Code:

Private Sub DecFile()
        Dim fsRead As New FileStream("c:\pic.jpg", FileMode.Open)
        Dim msEncrypted As New MemoryStream(fsRead.Length)
        Dim msPlain As MemoryStream
        Dim brRead As New BinaryReader(fsRead)
 
        Dim bytesRead As Byte() = brRead.ReadBytes(fsRead.Length)
        msEncrypted.Write(bytesRead, 0, fsRead.Length)
 
        Dim x As New Crypto("password")
 
        msPlain = x.DecryptStream(msEncrypted)
 
        'write to fswrite
 
        Dim fsWrite As New FileStream("c:\orignalfile.jpg", FileMode.Create, FileAccess.Write)
 
        Dim decryptedFile() As Byte
 
        decryptedFile = msEncrypted.ToArray
 
        Dim I As Long
 
        For I = 0 To UBound(decryptedFile)
            fsWrite.WriteByte(decryptedFile(I))
        Next
 
        fsWrite.Close()
        fsRead.Close()
        msPlain.Close()
        msEncrypted.Close()
        brRead.Close()
 
    End Sub
 
    Private Sub EncFile()
        Dim fsRead As New FileStream("c:\test.jpg", FileMode.Open)
 
        Dim msPlain As New MemoryStream(fsRead.Length)
        Dim msEncrypted As MemoryStream
        Dim brRead As New BinaryReader(fsRead)
 
        'Read File into msPlain
        Dim bytesRead As Byte() = brRead.ReadBytes(fsRead.Length)
        msPlain.Write(bytesRead, 0, fsRead.Length)
 
        'Encrypt msPlain
 
        Dim x As New Crypto("password")
 
        msEncrypted = x.EncryptStream(msPlain)
 
        'Write to fsWrite somehow
 
        Dim fsWrite As New FileStream("c:\streamout.jpg", FileMode.Create, FileAccess.Write)
        Dim EncryptedFile() As Byte
 
        EncryptedFile = msEncrypted.ToArray
 
        Dim I As Long
 
        For I = 0 To UBound(EncryptedFile)
            fsWrite.WriteByte(EncryptedFile(I))
        Next
 
        fsWrite.Close()
        fsRead.Close()
        msPlain.Close()
        msEncrypted.Close()
        brRead.Close()
 
    End Sub

was having trouble with decrypting the streams so I wrote this to test and the decryption function (in the class) is not working (i think) anyone know whats wrong?

(how come .vb is not a vaild extension?)

Umm , what VS.NET version have you got ? Because MS were talking about some differences in Cryptograph Class a while back .

Try this file en/de-cryption .

So Is this right? (I want to load the encrypted file with out decrypting it to the users disk) Im using VS .NET 03.

VB Code:

Private Sub DecryptFile()
            Try
                If password.Length > 8 Then
                    password = password.Substring(0, 8)
                Else
                    If password.Length < 8 Then
                        Dim add As Integer = 8 - password.Length
                        Dim i As Integer
                        For i = 0 To add - 1
                            password = password + i
                        Next i
                    End If
                End If
                Dim UE As New UnicodeEncoding
                Dim key As Byte() = UE.GetBytes(password)
 
                Dim fsCrypt As New FileStream(textBox2.Text, FileMode.Open)
 
                Dim RMCrypto As New RijndaelManaged
 
                Dim cs As New CryptoStream(fsCrypt, RMCrypto.CreateDecryptor(key, key), CryptoStreamMode.Read)
 
                Dim msDec As New MemoryStream
 
                Dim data As Integer
                While (data = cs.ReadByte()) <> -1
                    msDec.WriteByte(CByte(data))
                End While
                'Load Into picturebox
 
                Picturebox1.Image = New Bitmap (msdec)                
 
                msDec.Close()
                cs.Close()
                fsCrypt.Close()
                MessageBox.Show("Everything is OK", "OK")
            Catch
            End Try
        End Sub 'DecryptFile

I dont know whether there was some thing wrong with the code you gave me or I changed it by accident but I figured it out and got it working propertly. Now im gonna strip the code down and throw it into a class.

{Class attached}

Sample Usage

form declarations

VB Code:

WithEvents Crypt as cCrypt ' change withEvents to dim if you 'dont want to trap the error event

encryption code

VB Code:

Dim Crypt as new cCrypt
 
With Crypt
    .Password = "password"
    .PlainFile = "c:\test.txt" 'this is the file you want to encrypt
    .EncryptedFile = "c:\encrypted test.txt" 'this is where the encrypted file is stored
    .EncryptFile ' to Encrypt the file
End with

VB Code:

Dim Crypt as new cCrypt
 
With Crypt
    .Password = "password"
    .PlainFile = "c:\decrypted test.txt" 'this is where you want the decrypted file to go
    .EncryptedFile = "c:\encrypted test.txt" 'this is where the encrypted file is stored
    .DecryptFile ' to decrypt the file
    'If you want to look at a encrypted jpg w/o decrypting it to disk
    'use this
     Picturebox1.Image = .DecryptPicture
     'this decrypts the file in memory
End with

Good it's working now . Yes the proj is converted into VB.NET 2003 .