1:  Class Symmertric

   2:   

   3:      Dim RMCrypto As New Security.Cryptography.RijndaelManaged()

   4:      Public Property Key As Byte()

   5:      Public Property IV As Byte()

   6:   

   7:      Public Sub CreateKey()

   8:          RMCrypto.GenerateIV()

   9:          IV = RMCrypto.IV

  10:          RMCrypto.GenerateKey()

  11:          Key = RMCrypto.Key

  12:      End Sub

  13:   

  14:      'выдает на выход сгененрированный ключ, IV и выходным параметром - криптованную строку

  15:      Public Function EnCryptString(ByVal InputStr As String) As String

  16:          Try

  17:              Dim InputArr() As Byte = (New System.Text.UnicodeEncoding).GetBytes(InputStr)

  18:              Dim MemStream As New IO.MemoryStream(InputArr)

  19:              Dim CryptStream1 As New Security.Cryptography.CryptoStream(MemStream, RMCrypto.CreateEncryptor(Key, IV), Security.Cryptography.CryptoStreamMode.Read)

  20:              Dim CryptoArrLength As Integer = (InputStr.Length + 32) * 2 'размер буфера (примерный)

  21:              Dim OutArr(CryptoArrLength) As Byte, I As Integer, OneByte As Byte

  22:              While True

  23:                  Try

  24:                      OneByte = CryptStream1.ReadByte

  25:                  Catch ex As System.OverflowException

  26:                      Exit While

  27:                  End Try

  28:                  OutArr(I) = OneByte

  29:                  I += 1

  30:              End While

  31:              MemStream.Close()

  32:              CryptStream1.Close()

  33:              ReDim Preserve OutArr(I - 1)

  34:              Dim OutBuilder As New System.Text.StringBuilder

  35:              For j As Integer = 0 To OutArr.Length - 1

  36:                  OutBuilder.AppendFormat("{0:X2}", OutArr(j))

  37:              Next

  38:              Return OutBuilder.ToString

  39:          Catch ex As Exception

  40:              MsgBox(ex.Message)

  41:          End Try

  42:      End Function

  43:   

  44:      'кушает на входе ключ, IV, криптованную строку и выдает расшифрованную строку

  45:      Public Function DeCryptString(ByVal InputStr As String) As String

  46:          Try

  47:              Dim CryptoArrLength As Integer = (InputStr.Length + 32) * 2 'размер буфера (примерный)

  48:              Dim InputArr(CryptoArrLength) As Byte, I As Integer, OneByte As Byte

  49:              For I = 0 To InputStr.Length / 2 - 1

  50:                  OneByte = Byte.Parse(InputStr.Substring(I * 2, 2), Globalization.NumberStyles.AllowHexSpecifier)

  51:                  InputArr(I) = OneByte

  52:              Next

  53:              ReDim Preserve InputArr(I - 1)

  54:              Dim MemStream As New IO.MemoryStream(InputArr)

  55:              Dim CryptStream1 As New Security.Cryptography.CryptoStream(MemStream, RMCrypto.CreateDecryptor(Key, IV), Security.Cryptography.CryptoStreamMode.Read)

  56:              Dim OutArr(CryptoArrLength) As Byte, j As Integer

  57:              If OutArr.Length = 0 Then

  58:                  Return "" 'не расшифровало ничего вообще

  59:              Else

  60:                  While True

  61:                      Try

  62:                          OneByte = CryptStream1.ReadByte

  63:                      Catch ex As System.OverflowException

  64:                          Exit While

  65:                      End Try

  66:                      OutArr(j) = OneByte

  67:                      j += 1

  68:                  End While

  69:                  MemStream.Close()

  70:                  CryptStream1.Close()

  71:                  ReDim Preserve OutArr(j - 1)

  72:                  Return (New System.Text.UnicodeEncoding).GetString(OutArr)

  73:              End If

  74:          Catch ex As Exception

  75:              If ex.GetType.FullName = "System.Security.Cryptography.CryptographicException" Then

  76:                  Return "@?@" 'не расшифровало, сменились Key,IV - OutArr из нулей

  77:              Else

  78:                  MsgBox(ex.Message)

  79:              End If

  80:   

  81:          End Try

  82:      End Function

  83:  End Class

   1:  Public Class EditForm

  ...   

   5:      Dim Crypter As New Symmertric

  ...   

  12:              With CurEditRow

  13:                  LoginTextBox.Text = .Login

  14:                  PassTextBox.Text = IIf(Crypter.DeCryptString(.Pass) = "@?@", "", Crypter.DeCryptString(.Pass))

  32:                  Dim R As Site = Db.Rows.Where(Function(X) X.I = CurEditRow.I).FirstOrDefault

  33:                  R.Login = LoginTextBox.Text

  34:                  R.Pass = Crypter.EnCryptString(PassTextBox.Text)

  ...   

  49:                  Db.DbSaveChange()