Imports System
Imports System.IO
Imports System.Text
Imports System.Security.Cryptography
Module Module1
Public Function Encrypt(ByVal plainText As String, ByVal passPhrase As String, ByVal saltValue As String, _
ByVal hashAlgorithm As String, ByVal passwordIterations As Integer, ByVal initVector As String, ByVal keySize As Integer) As String
' Convert strings into byte arrays.
' Let us assume that strings only contain ASCII codes.
' If strings include Unicode characters, use Unicode, UTF7, or UTF8
' encoding.
Dim initVectorBytes As Byte()
initVectorBytes = Encoding.ASCII.GetBytes(initVector)
Dim saltValueBytes As Byte()
saltValueBytes = Encoding.ASCII.GetBytes(saltValue)
' Convert our plaintext into a byte array.
' Let us assume that plaintext contains UTF8-encoded characters.
Dim plainTextBytes As Byte()
plainTextBytes = Encoding.UTF8.GetBytes(plainText)
' First, we must create a password, from which the key will be derived.
' This password will be generated from the specified passphrase and
' salt value. The password will be created using the specified hash
' algorithm. Password creation can be done in several iterations.
Dim password As PasswordDeriveBytes
password = New PasswordDeriveBytes(passPhrase, _
saltValueBytes, _
hashAlgorithm, _
passwordIterations)
' Use the password to generate pseudo-random bytes for the encryption
' key. Specify the size of the key in bytes (instead of bits).
Dim keyBytes As Byte()
keyBytes = password.GetBytes(keySize / 32)
' Create uninitialized Rijndael encryption object.
Dim symmetricKey As RijndaelManaged
symmetricKey = New RijndaelManaged
' It is reasonable to set encryption mode to Cipher Block Chaining
' (CBC). Use default options for other symmetric key parameters.
symmetricKey.Mode = CipherMode.CBC
' Generate encryptor from the existing key bytes and initialization
' vector. Key size will be defined based on the number of the key
' bytes.
Dim encryptor As ICryptoTransform
encryptor = symmetricKey.CreateEncryptor(keyBytes, initVectorBytes)
' Define memory stream which will be used to hold encrypted data.
Dim memoryStream As MemoryStream
memoryStream = New MemoryStream
' Define cryptographic stream (always use Write mode for encryption).
Dim cryptoStream As CryptoStream
cryptoStream = New CryptoStream(memoryStream, _
encryptor, _
CryptoStreamMode.Write)
' Start encrypting.
cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length)
' Finish encrypting.
cryptoStream.FlushFinalBlock()
' Convert our encrypted data from a memory stream into a byte array.
Dim cipherTextBytes As Byte()
cipherTextBytes = memoryStream.ToArray()
' Close both streams.
memoryStream.Close()
cryptoStream.Close()
' Convert encrypted data into a base64-encoded string.
Dim cipherText As String
cipherText = Convert.ToBase64String(cipherTextBytes)
' Return encrypted string.
Encrypt = cipherText
End Function
End Module
