Trucos de Visual Basic.NET Encriptación - Desencriptación

Para encriptar y desencriptar datos podemos utilizar las siguientes funciones:

Public Shared Function EncryptString(ByVal InputString As String, ByVal SecretKey As String, Optional ByVal CyphMode As CipherMode = CipherMode.ECB) As String
Try
Dim Des As New TripleDESCryptoServiceProvider
'Put the string into a byte array
Dim InputbyteArray() As Byte = Encoding.UTF8.GetBytes(InputString)
'Create the crypto objects, with the key, as passed in
Dim hashMD5 As New MD5CryptoServiceProvider
Des.Key = hashMD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(SecretKey))
Des.Mode = CyphMode
Dim ms As MemoryStream = New MemoryStream
Dim cs As CryptoStream = New CryptoStream(ms, Des.CreateEncryptor(), _
CryptoStreamMode.Write)
'Write the byte array into the crypto stream
'(It will end up in the memory stream)
cs.Write(InputbyteArray, 0, InputbyteArray.Length)
cs.FlushFinalBlock()
'Get the data back from the memory stream, and into a string
Dim ret As StringBuilder = New StringBuilder
Dim b() As Byte = ms.ToArray
ms.Close()
Dim I As Integer
For I = 0 To UBound(b)
'Format as hex
ret.AppendFormat("{0:X2}", b(I))
Next

Return ret.ToString()
Catch ex As System.Security.Cryptography.CryptographicException
ExceptionManager.Publish(ex)
Return ""
End Try

End Function

Public Shared Function DecryptString(ByVal InputString As String, ByVal SecretKey As String, Optional ByVal CyphMode As CipherMode = CipherMode.ECB) As String
If InputString = String.Empty Then
Return ""
Else
Dim Des As New TripleDESCryptoServiceProvider
'Put the string into a byte array
Dim InputbyteArray(CType(InputString.Length / 2 - 1, Integer)) As Byte '= Encoding.UTF8.GetBytes(InputString)
'Create the crypto objects, with the key, as passed in
Dim hashMD5 As New MD5CryptoServiceProvider

Des.Key = hashMD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(SecretKey))
Des.Mode = CyphMode
'Put the input string into the byte array

Dim X As Integer

For X = 0 To InputbyteArray.Length - 1
Dim IJ As Int32 = (Convert.ToInt32(InputString.Substring(X * 2, 2), 16))
Dim BT As New ByteConverter
InputbyteArray(X) = New Byte
InputbyteArray(X) = CType(BT.ConvertTo(IJ, GetType(Byte)), Byte)
Next

Dim ms As MemoryStream = New MemoryStream
Dim cs As CryptoStream = New CryptoStream(ms, Des.CreateDecryptor(), _
CryptoStreamMode.Write)

'Flush the data through the crypto stream into the memory stream
cs.Write(InputbyteArray, 0, InputbyteArray.Length)
cs.FlushFinalBlock()

'//Get the decrypted data back from the memory stream
Dim ret As StringBuilder = New StringBuilder
Dim B() As Byte = ms.ToArray

ms.Close()

Dim I As Integer

For I = 0 To UBound(B)
ret.Append(Chr(B(I)))
Next

Return ret.ToString()
End If
End Function