Encryption

[David]

Hope someone can help or have a free control. I am going to be passing
data from a client computer to a server via a winsock control. I want
to encrypt/decript the contents of the string that is passed back and
forth. Anyone have any ideas?

David

[Eddie B]

Re: Encryption

Are you using VB6 or .Net? .Net has an encryption class you could use
- System.Security .Cryptography

Here is the code for a DLL I use for that same reason. The Sub Main
routine is commented out, it will generate a key, but I use the same
one, so I don't need this part.

=============== =============== ==========

Imports System
Imports System.IO
Imports System.Security
Imports System.Security .Cryptography
Imports System.Runtime. InteropServices
Imports System.Text


Public Class Class1


' Call this function to remove the key from memory after it is
used for security.
<DllImport("ker nel32.dll")> _
Public Sub ZeroMemory(ByVa l addr As IntPtr, ByVal size As Integer)
End Sub

' Function to generate a 64-bit key.
Function GenerateKey() As String
' Create an instance of a symmetric algorithm. The key and the
IV are generated automatically.
Dim desCrypto As DESCryptoServic eProvider =
DESCryptoServic eProvider.Creat e()

' Use the automatically generated key for encryption.
Return ASCIIEncoding.A SCII.GetString( desCrypto.Key)

End Function

Public Shared Function EncryptFile(ByV al sInputFilename As String,
_
ByVal sOutputFilename As String, _
ByVal sKey As String) As String

On Error GoTo errhandle

Dim fsInput As New FileStream(sInp utFilename, _
FileMode.Open, FileAccess.Read )
Dim fsEncrypted As New FileStream(sOut putFilename, _
FileMode.Create , FileAccess.Writ e)

Dim DES As New DESCryptoServic eProvider

'Set secret key for DES algorithm.
'A 64-bit key and an IV are required for this provider.
DES.Key = ASCIIEncoding.A SCII.GetBytes(s Key)

'Set the initialization vector.
DES.IV = ASCIIEncoding.A SCII.GetBytes(s Key)

'Create the DES encryptor from this instance.
Dim desencrypt As ICryptoTransfor m = DES.CreateEncry ptor()
'Create the crypto stream that transforms the file stream by
using DES encryption.
Dim cryptostream As New CryptoStream(fs Encrypted, _
desencrypt, _
CryptoStreamMod e.Write)

'Read the file text to the byte array.
Dim bytearrayinput( fsInput.Length - 1) As Byte
fsInput.Read(by tearrayinput, 0, bytearrayinput. Length)
'Write out the DES encrypted file.
cryptostream.Wr ite(bytearrayin put, 0, bytearrayinput. Length)
cryptostream.Cl ose()

Return sOutputFilename

Exit Function

errhandle:
Return "Error Encrypting File!" & vbCrLf & Err.Description

End Function

Public Shared Function DecryptFile(ByV al sInputFilename As String,
_
ByVal sOutputFilename As String, _
ByVal sKey As String) As String

On Error GoTo errhandle

Dim DES As New DESCryptoServic eProvider

'A 64-bit key and an IV are required for this provider.

'Set the secret key for the DES algorithm.
DES.Key() = ASCIIEncoding.A SCII.GetBytes(s Key)

'Set the initialization vector.
DES.IV = ASCIIEncoding.A SCII.GetBytes(s Key)

'Create the file stream to read the encrypted file back.
Dim fsread As New FileStream(sInp utFilename, FileMode.Open,
FileAccess.Read )

'Create the DES decryptor from the DES instance.
Dim desdecrypt As ICryptoTransfor m = DES.CreateDecry ptor()

'Create the crypto stream set to read and to do a DES
decryption transform on incoming bytes.
Dim cryptostreamDec r As New CryptoStream(fs read, desdecrypt,
CryptoStreamMod e.Read)

'Print out the contents of the decrypted file.
Dim fsDecrypted As New StreamWriter(sO utputFilename)

fsDecrypted.Wri te(New
StreamReader(cr yptostreamDecr) .ReadToEnd)
fsDecrypted.Flu sh()
fsDecrypted.Clo se()

Return sOutputFilename

Exit Function

errhandle:
Return "Error Encrypting File!" & vbCrLf & Err.Description

End Function

Public Sub Main()
'Must be 64 bits, 8 bytes.
'Dim sSecretKey As String

' Get the key for the file to encrypt.
' You can distribute this key to the user who will decrypt the
file.
'sSecretKey = GenerateKey()

' For additional security, pin the key.
'Dim gch As GCHandle = GCHandle.Alloc( sSecreyKey,
GCHandleType.Pi nned)


' Encrypt the file.
'EncryptFile(Ap plication.Start upPath & "\settings.ini" , _
' Application.Sta rtupPath & "\Encrypted.txt ", _
' sSecretKey)

' Decrypt the file.
'DecryptFile(ap plication.Start upPath & "\Encrypted.txt ", _
' application.Sta rtupPath & "\Decrypted.txt ", _
' sSecretKey)

' Remove the key from memory.
'ZeroMemory(gch .AddrOfPinnedOb ject(), sSecretKey.Leng th * 2)
'gch.Free()
End Sub
End Class

Hope this helps!

On 4 Aug 2004 10:24:58 -0700, dhodgkins@chest nut.org (David) wrote:
[color=blue]
>Hope someone can help or have a free control. I am going to be passing
>data from a client computer to a server via a winsock control. I want
>to encrypt/decript the contents of the string that is passed back and
>forth. Anyone have any ideas?
>
>David[/color]

[David]

Re: Encryption

dhodgkins@chest nut.org (David) wrote in message news:<83b47ff1. 0408040924.3742 358f@posting.go ogle.com>...[color=blue]
> Hope someone can help or have a free control. I am going to be passing
> data from a client computer to a server via a winsock control. I want
> to encrypt/decript the contents of the string that is passed back and
> forth. Anyone have any ideas?
>
> David[/color]

Thanks, but never mind. I found it.

David