Hello,
there is problem with subject I mean page 129 to 132
and unfotunately there were no source code for that part all in all I think it is a bit
foggy and I need some friendly explanation to cover that part and what is the usage of this subject in E-commerce?please help me

Well there's code in page 130. Basically you're computing a checksum on the data, via the GenerateMac() function and checking it with IsMacValid().

So you generate a key for validation using the GenerateRandomBytes() method on page 127, and then pass it, along with the text you want to calculate the checksum for into GenerateMac() then when you retrieve your data, after you unencrypt it, you validate the generated MAC

Hello Blowdart again,


you know till page 128 every thing is ok and I have a system .but how to ensure that date does not change ?

You'd put it before you store the data somewhere, for example, a database. The demo scripts don't do storage, hence it's hard to put it in that example.

If you look at the step by step process starting on page 131 you'll see it as step 3 in adding a new record, step 6 in retrieving and step 3 in updating.

Hello again ,

is there any fuctional example for that??

Not really - because an example would make too many assumptions about workflow within a target system (or end up needing a database to demonstrate etc.), there's no way beyond the steps to make it generic or a short example.