OK, I have a program that successfully encrypts files using the des encryption, but when I try to encrypt rather large files, I cannot. I believe this is because all the data is loaded into the memory, which, when loading a large file, makes sense that I have a problem.
How could I, if possible, encrypt one byte, then write it to a file and take the next byte, etc...Code:' Create input and output file streams.
If in_file.Length = 0 Then Call Errors(0) : Exit Sub
If out_file.Length = 0 Then Call Errors(1) : Exit Sub
Dim in_stream As New FileStream(in_file, FileMode.Open, FileAccess.Read)
Dim out_stream As New FileStream(out_file, FileMode.Create, FileAccess.Write)
' Make a triple DES service provider.
Dim des_provider As New TripleDESCryptoServiceProvider
' Find a valid key size for this provider.
Dim key_size_bits As Integer = 0
For i As Integer = 1024 To 1 Step -1
If des_provider.ValidKeySize(i) Then
key_size_bits = i
Exit For
End If
Next i
Debug.Assert(key_size_bits > 0)
' Get the block size for this provider.
Dim block_size_bits As Integer = des_provider.BlockSize
frmProgress.ProgressBar1.Step = block_size_bits
' Generate the key and initialization vector.
Dim key As Byte() = Nothing
Dim iv As Byte() = Nothing
MakeKeyAndIV(password, key_size_bits, block_size_bits, key, iv)
' Make the encryptor or decryptor.
Dim crypto_transform As ICryptoTransform
If encrypt Then
crypto_transform = des_provider.CreateEncryptor(key, iv)
Else
crypto_transform = des_provider.CreateDecryptor(key, iv)
End If
' Attach a crypto stream to the output stream.
Dim crypto_stream As New CryptoStream(out_stream, crypto_transform, CryptoStreamMode.Write)
' Encrypt or decrypt the file.
Const BLOCK_SIZE As Integer = 1024
Dim buffer(BLOCK_SIZE) As Byte
Dim bytes_read As Integer
Me.cmdEncrypt.Enabled = False
Do
' Read some bytes.
bytes_read = in_stream.Read(buffer, 0, BLOCK_SIZE)
If bytes_read = 0 Then Exit Do
System.Windows.Forms.Application.DoEvents()
' Write the bytes into the CryptoStream.
crypto_stream.Write(buffer, 0, bytes_read)
Loop
' Close the streams.
crypto_stream.Close()
in_stream.Close()
out_stream.Close()
FileClose()
Me.cmdEncrypt.Enabled = True
