3DES Public-Key Encryption using Digital Certificates

Download: Chilkat .NET Assemblies

VB.NET source code showing how to do 3DES public-key encryption and decryption.

        ' This example uses the Chilkat .NET encryption library, which can be downloaded
        ' at http://www.chilkatsoft.com/downloads.asp

        ' Create an instance of the Chilkat encryption class.
        Dim success As Boolean
        Dim crypt As New Chilkat.Crypt2()

        ' Any code begins the 30-day trial.
        crypt.UnlockComponent("30-day-trial")

        ' Use public-key encryption.
        crypt.CryptAlgorithm = "PKI"

        ' Use 3DES encryption.
        Dim csp As New Chilkat.Csp()
        csp.SetProviderMicrosoftEnhanced()
        csp.SetEncryptAlgorithm("3DES")
        crypt.SetCSP(csp)

        ' Load a certificate from a .cer file
        ' There are many other ways of loading a certificate...
        Dim cert As New Chilkat.Cert()
        success = cert.LoadFromFile("myCert.cer")
        If (Not success) Then
            MsgBox(cert.LastErrorText)
            Exit Sub
        End If

        ' Tell the crypt object to use the certificate.
        crypt.SetEncryptCert(cert)

        ' Tell the crypt object to base-64 encode the encrypted data.
        crypt.EncodingMode = "base64"

        ' File a byte array to encrypt
        Dim inputData(10) As Byte
        Dim i As Integer
        For i = 1 To 10
            inputData(i) = i
        Next

        ' Encrypt the byte array.
        ' To encrypt, only the public-key is needed (when using PKI).
        Dim eStr As String
        eStr = crypt.EncryptBytesENC(inputData)
        If (eStr.Length = 0) Then
            MsgBox(crypt.LastErrorText)
            Exit Sub
        End If

        MsgBox("Data encrypted: " & eStr)

        ' Now decrypt...
        ' To decrypt, the private key is needed.  If this step fails but the encryption succeeded,
        ' it is probably because the public key is installed and accessible, but not the private key.
        Dim decrypted() As Byte
        decrypted = crypt.DecryptBytesENC(eStr)

        MsgBox("Decrypted length = " & Str(decrypted.Length))

        If (decrypted.Length = 0) Then
            MsgBox(crypt.LastErrorText)
        Else
            For i = 0 To decrypted.Length - 1
                If (decrypted(i) <> i) Then
                    MsgBox("Error in decrypted data!")
                End If
            Next
        End If

Important: The download for this example does not contain the ChilkatDotNet.dll which
must be downloaded and installed separately at http://www.chilkatsoft.com/downloads.asp.
Once installed, add a reference to the DLL in the project by following the instructions at
http://www.example-code.com/vbdotnet/step2.asp