Data encryption

Introduction

Data security is important when we are dealing with the Internet and mobile applications. If you have data that is confidential stored on your Pocket PC device and it gets stolen, you want to ensure that the data is protected at the same time. Consider the importance of a company’s client list getting into the hands of a competitor!

At the same time, you may be transmitting confidential information such as customer’s payment and bank details over the Internet when you synchronise with your central server. Encrypting the data file that you use for the transfer will ensure that it cannot be intercepted and read or modified by a third party.

Sapphire Solutions (http://www.sapphire-solutions.co.uk) have developed an easy to use utility that solves this problem. They have developed the Sapphire Encrypt Utility that can encrypt/decrypt a file or even plain text.

Utility overview

The Sapphire Encrypt Utility is a small DLL that plugs into eVB or VB.NET/C#. The utility can encrypt/decrypt a file or even plain text. Sapphire have also developed a Win32 counterpart of the DLL so that you could develop a PC application to work on the server. This could either be mounted onto a web site or through a back office system. So even if you’re not developing a mobile application, it is still a utility worth considering.

Feature list

The Sapphire Encrypt Utility provides the following functionality:

• Encrypt a plain text string using a specified key
• Decrypt a plain text string specifying the key
• Encrypt a file using a specified key
• Decrypt a file using a specified key

Running the demo project

Sapphire have also provided an extensive demo project in both eMbedded Visual Basic and VB.NET that show how to use all the functions of the DLL. You get all the eVB and VB.NET source code which is not only great for experienced programmers to implement the utility, but also great for new programmers to see how the application has been approached.

The latest version of the Sapphire Encrypt Utility can be downloaded from their web site here:
http://www.sapphire-solutions.co.uk/product.asp?product=ENCRYPT

Once you have downloaded the demo project and unzip it, you will have two versions of the demo project, one for eVB and the other for VB.NET. You will also have a folder containing the different DLLs compiled for the different devices.

Simply select the DLL that matches the device. If you are developing in eVB, then you will need to copy the DLL to the \Windows\ path. Alternatively, if you are developing in VB.NET or C#, you need to copy the DLL to the application path. Check the project settings to see where the demo project will deploy itself to.

Now you are ready to run the demo. Please note the following screenshots have been taken from the VB.NET demo project.

Encrypting and decrypting text

Sample code

Encrypting Text

Dim sEncrypted As Integer

Dim sNew As String

' Fill sNew to force the string variable to a sufficient size for the returned string

sNew = Space(1000)

sEncrypted = sEncryptText(txtOriginal.Text, sNew, txtPassword.Text, 1234567890, True)

txtEncrypted.Text = StripString(sNew)

If sEncrypted = 0 Then

  MsgBox("Encrypted")

Else

  MsgBox("Problem")

End If

Decrypting Text

Dim sDecrypted As Integer

Dim sNew As String

' Fill sNew to force the string variable to a sufficient size for the returned string

sNew = Space(1000)

sDecrypted = sDecryptText(txtEncrypted.Text, sNew, txtPassword.Text, 1234567890, True)

txtDecrypted.Text = StripString(sNew)

If sDecrypted = 0 Then

  MsgBox("Decrypted")

Else

  MsgBox("Problem")

End If

Manual documentation

Sapphire Solutions also provide a comprehensive manual for all their utilities. It includes a definition of the DLL function calls, some sample code and FAQs to help with any troubleshooting.

Their manual documentation can be viewed online, downloaded as a HTML document for offline use and even a downloadable Windows help file. These can all be found on their web site at http://www.sapphire-solutions.co.uk/manual.

Licence of use

Sapphire Solutions provide an unlimited use demo version of the Sapphire Encrypt Utility. While the product will function as normal, the user will receive a popup message stating that it is a demo version. It is great for trying out the utility, checking device compatibility, building it into your application and selling the idea to your customer. Students can use it as well for their college or university projects without having to purchase it either.

Of course though, for commercial applications being developed you will need to get a licence for the utility to make it run without any pop-ups. The good thing about Sapphire’s pricing policy is that it is a one off fee and you or your company can use it as many times as you like for your projects royalty free. There are no royalties required for rolling out your application to your client.

With that you will also get 12 months support via email to their experienced technical team. They also provide upgrades for the latest versions at discounted prices which also extend the 12 months support by a further 12 months.